Detonating 493 and what I did to stop it.

[Kern Dog]

Its been awhile since I have posted about this, but I have a few updates to pass along.

I built this 440/493 in 2004. I wanted a fast streetable engine that would run on pump gas. I bought a rotating assembly from an ad in a magazine. The vendor told me that the compression ratio would work with pump gas. I have learned since then that many factors come into play to determine if an engine will run right or knock itself to death.
Over the years I have tried a few things to eliminate the knocking. All the while I have kept the same pistons in the engine.
The specs:
440 block, .030 over 4.35 bore Pistons sit .012 below deck. 4.15 stroke. .039 head gasket thickness, 4.410 bore.
Edelbrock aluminum heads, 84 ccs when new, probably 82 ccs after being resurfaced a few times.
Lunati 316/326 Solid Flat Tappet cam 261* intake, 271* exhaust duration @ .050. .556 lift INT, .578 EXH. Installed at 106.
The calculated compression ratio is 11.04 but when I measured the thickness of the gasket, it measures closer to .035. The .035 number makes the CR 11.14.  This with a quench distance between .047 to .051. The engine would knock at WOT on 91 octane even with total ignition timing limited to 30 degrees.
In 2004 when I first built the engine, I used the Mopar Performance 292/509 cam. I had it installed at 4 degrees advanced and the engine knock was terrible. I had a dyno shop tune the car. They rejetted the carb and recurved the distributor but I would still get detonation.

[Cooter]

I'm convinced with my iron headed 440 @ 10.8:1, that even todays "premium" fuel is just sh*t.
Mine has nowhere near the overlap of your cam but still a bit and it rattles.
Put true 100 octane in tank and no knock.
I even calculated out the .040 'quench' BS...still rattles. Even with aluminum heads, best to play it safe and stick to 10:1 on iron heads, and no more than 10.3:1 or so with aluminim heads.

Newer cars can get away with it due to electronics, but old school motors just can't.

[Kern Dog]

In 2006 I decided to try using a more modern camshaft, so I went with a Comp XE 285 HL. At the same time, I pulled the heads and installed .060 Cometic head gaskets. The engine ran great and didn't knock even with timing advanced to 35 degrees total. That cam went flat within about a month, so I swapped in another. The second cam went flat within the next couple of years. The engine didn't knock but it did start to burn oil and smoke at WOT. I put the 292/509 cam back in. The smoking still annoyed me.  I tried changing PCV valves, intake gaskets and valve stem seals because I suspected that oil was getting into the chambers somehow. I found some wear on the valve stems so I pulled the heads to replace a few valves. I didn't have the money to buy another set of Cometics, so I went back to the Fel Pro .039 gaskets since I had a few pair left over. The smoking was diminished but the knocking came back. This to me was proof that the thicker head gaskets did help stop the knocking.
In the Spring of 2011, I pulled the engine to stop the smoking problem. The machinist found that the rings were heavily worn but that the cylinders cleaned up just by honing. He told me that the knocking was probably from oil burning so I went back with the thin Fel Pro gaskets. I thought that NOW with fresh rings, clean chambers and all, the knocking problems were gone. I was wrong about that.
This year after a 1000 mile road trip, I decided that I had enough of this crap. I started asking around about what to do. Many suggested a change to a cam with a LATER intake closing. Upon the advice of a respected member of another Mopar website, I went with a Lunati solid flat tappet cam. Well, that cam ended up making things worse since it actually increased the cranking compression by an average of 5 lbs per cylinder. At this point, I decided to pull the heads yet again.

[Kern Dog]

The pistons all had crud on them. I suspect oil may have been getting in through the valley pan.

[Kern Dog]

I cleaned the pistons with solvent and looked for signs of detonation. I found no markings of any kind. Each piston looked totally fine without any damage of any kind.

[Kern Dog]

I was told that detonation leaves marks like an ice pick.

[Kern Dog]

Many builders like to talk about how "quench" can allow a high compression engine run on pump premium gas. When I have mentioned that I wanted to go with a thicker head gasket, they advised against it. They felt that I'd lose quench and might still detonate. While I appreciate the advice, I have a hard time believing that if I went with a thinner head gasket to get a better quench distance, I'd be okay with 11.24 compression. I am limited to 91 octane here unless I use race gas. My cranking compression is an average of 191 psi already. A thinner head gasket and higher CR would surely bump me to near 200. Can an engine with that high of a number run on pump gas? I have a hard time believing that.
I ordered a set of .075 Cometic MLS gaskets. Quench be damned, I'm moving forward with the thick gaskets. My ratio will be 10.07 and I'll be able to advance the timing to 35-36 degrees. Many have told me that the gains of running more ignition timing will MORE than make up for the loss of power from losing 9/10ths of a point of compression. Add to this the gain from porting the heads and I should reach to goal I've been reaching for since 2004: A fun, fast, streetable engine.

[deepockets]

wow, that's quite a story. so did you get past the cams going flat? what did you do to make things good there?

[cudaken]

 Red, what is your engine temperature? I have read here on the site that many people think 200 to 210 is OK for a BB Mopar? When I first read that I was going what the %$# are they talking about!   To me anything over 180 it is time to start looking for a places to pull over if I can not speed up. Hotter the car runs the easier it is to knock.

Have you made sure the fuel system is not to lean?

Are you sure the timing ring on the damper has not slipped? You could be running more timing than you think.  

Was the block deck height ever checked? I had one that was -.20 under blue printed deck height.

How much oil is the motor using if any?

My self I would be a little alarmed by the scratches in the last picture of the cylinder walls.

If the motor is running well and not smoking use some octane booster or water injection.

Cuda Ken

[Kern Dog]

The "flat cam" problem could have been a few things. I talked with Dwayne Porter over the Summer. He said that in 2005 or so, a "perfect shitstorm" came about where camshafts were cast with with softer metal, the lifters were being outsourced and built with inferior materials AND the oil companies dropped the levels of ZDDP in the engine oil without telling anyone. These events conspired to deliver the kiss of death to many enthusiasts. He also said while no flat tappet engine was immune, the milder the cam and valve spring, the better chance of survival. Since then, many people have experienced failures like I did.  I thought I did everything right as far as using plenty of cam lube and doing a proper break-in procedure. Both cams had one destroyed lobe. I went back to the Mopar 509 because I kept the lifters in order and I was short on cash.

The engine temperature has always been between 160 and 180. It has never boiled over or felt hot. I've never smelled coolant.
I run an AEM wideband Air-Fuel meter in the car. I jetted and adjusted the Demon 850 carb to run around 13.0 at WOT, 14.0 to 14.8 at idle and at cruise.
I never checked the deck height of the bare block, but I did check the distance of the piston to deck at TDC. Every cylinder checked out at .012 below deck, so the decks are square.
At present, the engine does not smoke at any time. Cranking compression is REALLY even among all cylinders. I read that anything below 10% variation between cylinders is okay for a street engine. My lowest was 185 and my highest was 192. That is a variance of less than 4 %.

[deepockets]

I have on order with Dwayne a solid for my build. went with the nitriding on the cam and edm lifters. i'll be running it on a test stand to break in the cam with just the outer springs. also using joe gibbs breakin oil. if it goes flat, god wanted it to.

[Kern Dog]

Funny... blaming GOD for a cam failure!
I went with Howards EDM lifters with this Lunati cam. I also figured that I need every advantage I can find to avoid another flat tappet failure. If i wipe another one, I'd be an idiot to NO step up to a roller cam.

[cudaken]

The engine temperature has always been between 160 and 180. It has never boiled over or felt hot. I've never smelled coolant.
I run an AEM wideband Air-Fuel meter in the car. I jetted and adjusted the Demon 850 carb to run around 13.0 at WOT, 14.0 to 14.8 at idle and at cruise.
I never checked the deck height of the bare block, but I did check the distance of the piston to deck at TDC. Every cylinder checked out at .012 below deck, so the decks are square.
At present, the engine does not smoke at any time. Cranking compression is REALLY even among all cylinders. I read that anything below 10% variation between cylinders is okay for a street engine. My lowest was 185 and my highest was 192. That is a variance of less than 4 %.

Red, only question I asked you did not answer was if you checked your timing ring.  Never know, it happens.

   Cuda Ken

[Supercharged Riot]

You should look at my build thread
I have pics of pistons that detonated.
Ur engine looks safe for another round
Good luck

[Kern Dog]

Sorry that I forgot to answer about the harmonic dampner. I checked it when I degreed the cam. I was happy to find that the TDC mark was correct.

[warpspeed]

My engine knocked fairly badly when first put on the road ten years ago. 

First thing I did to stop the knock was change to a higher octane which helped eliminate it completely.  So, I thought about what I could do to fix it without the race gas.

I went to 93/94 octane and put an insulator between the carb and intake.  Whow, that was good.  But, not quite enough.  So, I had to go do some more insulation by making sure the gas line isn't touching the engine on the way to the carb.  The hot engine brought up the temperature of the gas to the carb and caused a problem too.

Lastly, I had to take the distributor apart and weld up the weights  to stop the timing from going too high.  That was the final thing I had to do to stop it.  I used our friend Rick Ehrenberg for the help I needed to get that done.  The mopar distributor was over advancing the timing at speed.  It was fairly obvious as I looked at the timing, starting/idle timing all the way up to speed.  The diferential was way too much.

Now, the engine doesn't knock. It runs really hard no matter what the temperature. And my cam is a street/strip cam which is fairly agressive.

One other thing I noticed after taking it down last weekend, is the heat crossovers were not closed off.  Not sure if that would be a problem with a hotter intake and cause the knocking also, but, I don't really like that idea for a street driven car.  My other car with a 340 has them blocked off and that engine doesn't like cold driving temperatures.  (AT ALL!!)

One thing I noticed with my car ititally, is it didn't knock at all before it warmed up.  So, that was how I deduced the need to cool off the gas going into the engine beyond the carb.  Then the timing would never set correctly.  Either the timing was set too low for starting/idle to get the right timing for full advanced or the full advance was too much, which caused the knock, when the start/idle was correct.

[Kern Dog]

Good points, Warp.
The heads I have do not have a heat crossover. I don't drive it in cold or rainy weather anyway. Regarding the distributor, I have made some adjustments to mine in the interest of stopping the knock. It didn't help. I ran some 110 leaded gas and it didn't knock at all. That told me that the detonation wasn't permanent. I didn't want to be obligated to run race fuel at $60 for a 5 gallon jug.

[cudaken]

Red, did you look into water injection? I used it 25 to 30 years ago when I had my 426 Maxie with 12.5 to 1 compression. Sunco was gone so was 102 octane. At one time it was talked about a lot in Hot Rod, Car Craft and other magazines. Here is a link I found.

https://www.youtube.com/watch?v=HkPFZWd8wj4

While the video talks about boost engines, same thing applies with your problem. I am old and live through the time when High Performances Car owners where scrambling for any means to keep there cars on the road.

You have a old problem, so maybe looking at old ways to fix it might help? 

Cuda Ken   

[warpspeed]

Yep, race gas is expensive.  I think I will stick with the low compression engines for fun driving around.  High test is expensive enough.  I want to make  a 383 stroker for my 71 Challenger.  Not sure that will ever come to pass now.  Outside influences are going to stop that for sure now.  Good luck finding an answer.

[Kern Dog]

I have read about water and the water/methanol injection systems. I can't recall if they use a spacer plate under the carb like a nitrous oxide kit. Currently my air cleaner is very close to the hood. I don't have the room for a plate even 1/4" thick!
These head gaskets should make the difference that I need. If it doesn't, something else is very wrong inside....

[SRT-440]

Snow Performance has nice meth/water kit for N/A...and it does use a 1 inch plate under the carb...however, I think I read someone didn't use it and put the nozzles in the  chrome air cleaner lid. Not sure that would work tho.

[cudaken]

Snow Performance has nice meth/water kit for N/A...and it does use a 1 inch plate under the carb...however, I think I read someone didn't use it and put the nozzles in the  chrome air cleaner lid. Not sure that would work tho.

You can plume it into the air cleaner through the bottom plate. Places the nozzle over the carb. That is how I did it back in the day before there where under the carb plates.

Good luck and hope the thicker gaskets does the trick.

Cuda Ken

[Kern Dog]

Things have been so hectic lately with work, long commutes, busy weekends....
Today the boss decide to let us all leave early. I haven't seen my house in the daylight in awhile, so I'm heading out to the shop to begin reassembly!

[Kern Dog]

The heads are on. Headers too.
I hear about how some guys can R&R heads or entire engines in record time, but I have had mixed luck doing so. Maybe some of it is because of the car.....
I have to say that having 2" headers makes this sort of job a real pisser. To get the heads off, the headers have to come out. To get them out, the center link gets unbolted, the trans linkage too. This of course requires lifting the car to what feels like an almost unsafe height so the angle is right for installing or removing these headers. I'd never switch to manifolds, but I can see why many people stick with them.
Going back together, most of the header bolts are easily reached except near #1 and #2 tubes. I sometimes forget to tighten down the starter leads before bolting the starter in place. They are almost impossible to reach afterwards with the headers in place.
I'm almost there, just a few things on the top side to finish. I have both the Fel Pro intake paper gaskets and the thicker Mr Gasket ones. I figure that the thicker head gaskets may require thicker intake gaskets to manitain proper intake port alignment.

[Kern Dog]

The Charger is running again!   

Todays work went well. Not too many snags. Spark plugs are not much fun on these cars with headers. That may have been the biggest hurdle. I used NGK plugs this time, 2 steps colder than the Champions I was using before. I set timing to 19 initial and 33 total. I'm sure that I could advance it more. I need to run out the 110 gas and refill the tank with 91 octane. After that I'll reset the timing and consider rejetting the carb to achieve the ideal Air/Fuel readings. The wideband guage should be a big help there.
I have a Rev-n-nator ECU that I'd like to use. I tried it before when I had the 509 cam and nearly 11.0 compression but the engine detonated worse than ever even with timing retarded as per their instructions. I like the idea of having a rev limiter.

[2Luke2]

Awesome Red! Let us know how it turns out. It will be nice if you can get it all sorted out finally. Should definitely feel like a huge weight was removed from your shoulders after it's all said and done.

[505charger]

I built my 505 stroker for my Charger with Eddy heads, 240@ .050 cam, 10.7 compression. I live at 4000 feet. It pings like a pig on the 91 octane gas that is available. Checked timing, jetting, tdc Mark on the dampner. Still pinged on anything more than partial throttle.
        My cure was to mix 100LL avgas 50/50 with the 91 octane gas. I'm a pilot but it should not be a problem for most folks to find a small airport to buy the gas. $6/ gallon or less. A lot cheaper than race gas and cured my problem.
        I'm really upset at the bad advice I was given to push the compression so high. What would I have lost power wise with 10-1? 20 hp? It sure has been a pain to mix gas. I think conservative on compression would be the way to go. The engine is a beast! Everything I hoped for. Still working on a rear main seal leak. Seal number 4 this week. Having a pro put this one in.

[2Luke2]

I built my 505 stroker for my Charger with Eddy heads, 240@ .050 cam, 10.7 compression. I live at 4000 feet. It pings like a pig on the 91 octane gas that is available. Checked timing, jetting, tdc Mark on the dampner. Still pinged on anything more than partial throttle.
        My cure was to mix 100LL avgas 50/50 with the 91 octane gas. I'm a pilot but it should not be a problem for most folks to find a small airport to buy the gas. $6/ gallon or less. A lot cheaper than race gas and cured my problem.
        I'm really upset at the bad advice I was given to push the compression so high. What would I have lost power wise with 10-1? 20 hp? It sure has been a pain to mix gas. I think conservative on compression would be the way to go. The engine is a beast! Everything I hoped for. Still working on a rear main seal leak. Seal number 4 this week. Having a pro put this one in.

Where abouts are you located at 5,000 feet? We are at 6090 in Colorado Springs, we thought we had a pinging issue due to high compression. We tried to buy gas from a local airport and they said no can do. Is there a process to buying it?

[Kern Dog]

The practice of running race gas or mixing AVGAS with pump premium may have been okay if I only drove around here locally. I like driving the car and if the mood struck to take a road trip, I was SOL. The higher compression for me meant compromise. I had to limit my ignition timing to avoid knocking. If I ran the higher octane race fuel and advanced the timing, the car did run pretty strong without pinging.
Some feel that a point of compression could be worth 3-4% of the total HP. If I am making 400 HP to the tires, thats only 12-16 HP. Retarding the timing to avoid detonation has to cost more than that. This is why I decided to reduce the compression ratio and then advance the timing to a number that makes the most power without rattling.
My long work commute beats me down so I've had little time to get back to the car.
Maybe tomorrow?

[Kern Dog]

I decided to map the fuel curve in the car by taking the wife along to record the Air/Fuel readings while I drove.

Todays report:

* Idle in Neutral 1100-1200 rpms 13.1 to 13.5
* Idle in Gear 750-800 rpms 17.8 to 18.0 +

* Slow acceleration from 2000-3500 rpms 10,9 to 11.6
* Slow acceleration from 3000-5000 rpms 11.9 to 12.4

* Steady cruise @ 40 mph in OD 12.9 to 13.3
* Steady cruise @ 50 mph in OD 12.0 to 12.5
* Steady cruise @ 60 mph in OD 11.9 to 12.3

* Faster acceleration from 2000-3500 rpms 11.5 to 12.0
* Faster acceleration from 3000-5000 rpms 12.6 to 13.1

* WOT in 2nd gear, 2000-3500 rpms 12.9 to 13.1
* WOT in 2nd gear, 3500-6000 rpms 11.8 to 12.5
* Repeat run 11.6 to 12.1

*********************************************************************

With this info, I see that I need to richen it up a bunch at idle in gear. It stumbled and stalled twice while leaving 2 different stop signs. I suppose that since this occurs at idle and not on the primary circuit, this is a matter of tweaking the idle mixture screws?
I wouldn't think it would need more accelerator pump volume would it?

The "Slow acceleration" between 2000-3500 and 3000 to 5000 showed it to be really rich. This was done at light throttle , I assume entirely on the primary circuit? This makes me think I need to use smaller primary jets.

Steady cruise at 40, 50 and 60 were done in overdrive resulting in a final drive of 3.05 to one. The numbers there are more like what I'm supposed to have at WOT.

The faster acceleration testing showed leaner numbers than the slow acceleration. This was still done without hearing the secondaries open. I'm not sure what to make of that. Maybe I need a power valve that opens sooner there? I have a 3.5 in the carb now.

At WOT it shows that the higher RPMs it goes fatter. I guess that is safer than leaning out.

I welcome any suggestions or comments on my findings.
My gut tells me to adjust the idle mixture screws to obtain a richer in gear reading. It tells me to lean out the jetting front and rear. I'm not sure what to do regarding the Power valve. I'm not sure if I should use a lower rated one than the 3.5 I have.
Please tell me what you think!

[justcruisin]

Looking at your idle A/F ratio I would say you are dropping a lot of vacuum at 750 rpm and the idle circuit is not pulling the right amount of fuel. Not sure what the fix would be there but you need more fuel at those revs. I would try upping the revs to 850 in gear, why does it drag the revs down by 400 rpm, is the converter to tight? You may need to play with idle mix, IFR's and IAB's to get it right but 18:1 is no good. The right combo is going to be realized by experimenting. I would get your idle in gear around 13.5 - 14:1 with the idle screws and see what happens to the A/F at higher revs from there.

[oldschool]

I built my 505 stroker for my Charger with Eddy heads, 240@ .050 cam, 10.7 compression. I live at 4000 feet. It pings like a pig on the 91 octane gas that is available. Checked timing, jetting, tdc Mark on the dampner. Still pinged on anything more than partial throttle.
        My cure was to mix 100LL avgas 50/50 with the 91 octane gas. I'm a pilot but it should not be a problem for most folks to find a small airport to buy the gas. $6/ gallon or less. A lot cheaper than race gas and cured my problem.
        I'm really upset at the bad advice I was given to push the compression so high. What would I have lost power wise with 10-1? 20 hp? It sure has been a pain to mix gas. I think conservative on compression would be the way to go. The engine is a beast! Everything I hoped for. Still working on a rear main seal leak. Seal number 4 this week. Having a pro put this one in.

on a different note, what do you fly? I own and fly a Bonanza......

[Kern Dog]

I'm happy to report that the detonation seems to be behind me. Now its a matter of tuning the combination for a balance of power and efficiency.
Today I turned the idle mixture screws to 2 full turns out from bottom. The idle in gear A/F numbers went from high 17s to around 13.0. It responds much better with the fatter setting. The rpm drop going into gear is only 200-250 rpms. The idle vacuum isn't great but the engine feels better. I still need to lean out the carb for better cruise and WOT numbers.

[stuubi]

505Charger:Is your cam flat tappet,or roller?And i think that your and some other's problem with detonation in due to wrong cam.Intake side is closing too fast and causing cylinder pressures go to the roof.
Just change cam that has bigger value on intake closing and forget racegas-pump gas mixing.

Sound's to me that your pinging is caused by DCR(Dynamic Compression Ratio) being too high.
SCR(Static Compression Ratio) is what you are always talking about,DCR is what says how close to detonation with pumpgas you are.General rule of thumb is that DCR should float in 7.5-8.5 area,That's safe zone.

You can't mess whit SDR without machining,changing head's(always a big change),pistons.
DCR you can adjust by moving advance or retarding cam,or chancing different cam.

For examble,i helped a friend to build 383chevy that had AFR head's,Comp Cams X-Treme mech roller cam and true 10.5 comp.
When we tested it,with 32 degrees,it ran ok.So we gave little more to 36 asnd it detonaded so bad that even i heard it and i was standing outside of the car.
I created so much cylinder pressure that it forced head gascet ring to go around headstud!

We studied what caused it and find out about DCR.Calculated it and it was 8.9..
Changed to Comp's Magnum series,same degrees and lift,but mich more degrees on intake closing,and it survived 38degrees with no problems.Same piston's,head's etc.Only the cam was differen't.

[Kern Dog]

The issue of the Dynamic Compression Ratio is one that many are not aware of. I only read about it a few years ago and I have been a car guy since the 80s.
Take an 11.0 to 1 engine and run it with a HUGE cam and you might be able to get by on pump premium gasoline. That same engine with a milder cam would need MORE octane since a milder cam traps more cylinder pressure. The mechanical compression ratio is the same with both cams but the bigger cam results in less cylinder pressure.
Going the other way, Take an 8.0 to 1 engine and put in a small cam. That engine might make the exact same cranking compression as an 11.0 engine with a big cam since the smaller stick traps more pressure.

[stuubi]

Exat-ly-mundo.
I've talked with many,who had detonation,hard hot starting etc problem's and explained to them what is DCR.And when start to plan engine for myself or "customer",they allways think i'm weird because i spend so much time choosing cam,pistons and head's.

And this is why i dont understand why you have to start playing with mixing gas,retarding timing to a level you start to actually loose lot of power just because you builded engine that has wrong cam in it?
Get cam that work's and make more power on pump gas than previous combo with mix-up gas.

Even if you had roller cam,just take the 300-400 bucks and get another cam that suits your engine better.Buy race gas for 6 month's worth and most likely spended more than cost of new cam.

This is probably,most likely the reason people think that just strokin you engine makes it detonation sensitive.It's not the stroke or bore,it's too little cam.

[femtnmax]

Yes, dynamic compression ratio.   What was it before, and what is it now?   Was it ever calculated with measured data??   Sorry if I missed this info during reading your posts.

[Kern Dog]

Measured my compression ratio ?   
Uhhh, yes....many, many times. I've crunched the numbers using several online calculators and always arrived at the same numbers: 10.73 to 1.
THEN I pulled the heads and checked my numbers again.
Up until I had the heads off, I thought my pistons sat .017 in the hole. This time every hole was found to be .012 in the hole. Small discrepancy, but just wait...
I measured the old head gaskets. The are advertised to be .039 compressed but I measured .033 to .035. Again not a huge error but I was still not "Spot on" with the numbers. I had the heads ported and had the chambers open slightly. The man cc'd the chambers afterwards. They averaged at 82.5 ccs when they are listed to be 84ccs. I've had these heads on and off 2 engines a few times and have had them resurfaced slightly to get a good gasket seal.
My point is that the actual compression ratio I was running was closer to 11.22 to one when I thought I was at 10.73. One thing is certain, my cranking compression was 191 on average.
Regarding dynamic compression, I can now calculate 4 versions of what I came up with :
10.73 CR # & 509 cam : 7.98
11.22 CR # & 509 cam: 8.33
10.73 CR # & Lunati cam: 8.09
11.22 CR # & Lunati cam: 8.45


11.

[Kern Dog]

Now with 10.07 compression, my Dynamic CR with this Lunati is 7.61.

[femtnmax]

Measured my compression ratio ?   
Uhhh, yes....many, many times. I've crunched the numbers using several online calculators and always arrived at the same numbers: 10.73 to 1.

I don't know what your laughing at...your the one with the engine problem.
I asked what your dynamic ratio was.  It doesn't matter what the static ratio 10.73 is. 

[Kern Dog]

What, No sense of humor over there?
I was laughing because I have calculated the compression ratio many, many, many times. No need to retort with  "You're the one having engine problems".
I have tried many, many things to get this problem solved. I left no stone unturned. Part of the reason I write about it is to provide a record for others to see. I figured that it might be helpful to others.

[2Luke2]

Measured my compression ratio ?   
Uhhh, yes....many, many times. I've crunched the numbers using several online calculators and always arrived at the same numbers: 10.73 to 1.

I don't know what your laughing at...your the one with the engine problem.
I asked what your dynamic ratio was.  It doesn't matter what the static ratio 10.73 is. 

Femtnmax, I wouldn't get upset about it. Red had been dealing with this problem for awhile and while you may think he was laughing at you I believe he was more laughing at himself so he wouldn't cry when he actually thought about how many times he actually has measured.

[Kern Dog]

What guy hasn't measured?

Luke is right. I have done it so many times, often using different online calculators in an effort to find a different number. To me the question was the same as asking me if I like big chested women. No effort on my part to piss on anyones suggestions!

[stuubi]

Red 70 R/T 493:
I looked your story and read it again.I have to because i felt that i've missed something.
Pictures you put,shows glearly NO sign's of detonation.

I searched what i believe is your cam car for Lunati cam you are running.
30210912?Correct?Or 40312
It has same deg,but less lift?

http://static.summitracing.com/global/images/instructions/lun-40312.pdf

It says same 106 center you said you installed it.

If i found wrong cam,can you give me part nro?


Bore 4.35
Stroke 4.150
Below deck 0.012
and 6.750 con rod
Valve relief 6.6cc
Heads 82cc

Are these correct?

If they are,here's how i got your number's with Lunati Cam.


Static compression ratio of 10.98:1.
Effective stroke is 3.45 inches.
Your dynamic compression ratio is 9.30:1 .
Your dynamic cranking pressure is 192.98 PSI.

This calculation has almost identical Cranking pressure as you posted,but WAY higher DCR.
It is possible that detonation that you experienced,is minor,and is mainly caused by the fact that youre running really poor quench and too little timing to compensate that.And you builded heavily grud in your chambers.And that will start to burn on it's own if you have DCR thru the roof.

If you add quench,you'll "slow the head's",it slowes flame travel?This was open idea,not likely to be fact.
And you cant burn gas anymore effective way.

[Kern Dog]

Thanks for the suggestions. I think that your "effective stroke" is wrong though since mine is 4.15 inches.

[stuubi]

No it is not wrong.
Your stroke at crank is 4.15,but you have to think it this way:

When piston start's it's travel from bottom DC(BTDC),it start's 4.15" travel towards TDC,right?

As it start's to travel,there is intake valve still open,(check cam card,it says intake closes 56.5 ABDC(After bottom dead center).
When intake valve closes at 56.5 degrees,piston has traveled 0.7".
Do you follow?
4.15" minus 56.5deg=0.7" equals 3.45" of travel.

So when both valves are closed and ACTUAL compression starts,it has 3.45" of travel left to reach TDC.
You need less travel than that.So you do need a cam that has more degrees on intake closing side.

So this is your current Lunati with .039 gasket:
Static compression ratio of 10.98:1.
Effective stroke is 3.45 inches.
Your dynamic compression ratio is 9.30:1 .
Your dynamic cranking pressure is 192.98 PSI.

Change cam that has int closes at 70deg:
Static compression ratio of 10.98:1.
Effective stroke is 3.07 inches.
Your dynamic compression ratio is 8.38:1 .
Your dynamic cranking pressure is 168.81 PSI.

[XH29N0G]

Thank you both, and others for posting this problem solving process and the explanations.

[cdr]

No it is not wrong.
Your stroke at crank is 4.15,but you have to think it this way:

When piston start's it's travel from bottom DC(BTDC),it start's 4.15" travel towards TDC,right?

As it start's to travel,there is intake valve still open,(check cam card,it says intake closes 56.5 ABDC(After bottom dead center).
When intake valve closes at 56.5 degrees,piston has traveled 0.7".
Do you follow?
4.15" minus 56.5deg=0.7" equals 3.45" of travel.

So when both valves are closed and ACTUAL compression starts,it has 3.45" of travel left to reach TDC.
You need less travel than that.So you do need a cam that has more degrees on intake closing side.

So this is your current Lunati with .039 gasket:
Static compression ratio of 10.98:1.
Effective stroke is 3.45 inches.
Your dynamic compression ratio is 9.30:1 .
Your dynamic cranking pressure is 192.98 PSI.

Change cam that has int closes at 70deg:
Static compression ratio of 10.98:1.
Effective stroke is 3.07 inches.
Your dynamic compression ratio is 8.38:1 .
Your dynamic cranking pressure is 168.81 PSI.

you are correct stuubi

[2Luke2]

So that brings up the question... what was the DCR before?

[Kern Dog]

I have used online calculators that computed both the actual compression ratio and the dynamic ratio. I have never heard of the "effective stroke" term before. I see the point though. My cranking compression before switching to these .075 Cometic head gaskets was 191 on average.  The Lunati cam card shows an intake closing of 56.5 degrees @ .050. The dynamic calculators I've seen instruct to add 15 degrees to the .050 number.
The engine with the MP '509 cam had an average cranking compression # of 188. The entire point of installing that Lunati cam was to lower the dynamic & cranking numbers. I was given incorrect info on the intake closing of both the '509 and this Lunati. The 509 actually had a later intake closing so the Lunati cam was a step backward.

I have more carb and ignition tuning to do, but this weekend I'm adding an H pipe to the exhaust. I suppose that in some way this may skew the A/F numbers so I'll resume tuning after the exhaust work. Later down the road I might change to a 3 inch mandrel bent exhaust so I'll need to rejet the carb at that point too.

[Kern Dog]

Strange thing: Adding the Rev-N-Nator ECU made my A/F ratio go rich at cruise. I would have expected the thing to make the engine run cleaner due to it being a "better" unit.
I welded in the H pipe. I would have done an X but I don't have a way to make one of those. Anyhow, the exhaust tone quieted down some. It sounds less raspy than before at idle and at freeway speeds. I like that but I'm not finished yet.
The soggy feel at part throttle still annoys me. This is the result of using a high stall torque converter, OD gearing and a "race" oriented camshaft. If I ease into the gas at freeway speeds, the car feels lazy. If I lean into it harder, the car responds great.
I think that I am to the point where the rough idle and high rpms are too much for me. I want instant throttle response. I want to tap the gas off idle and start moving right away. This means I'll likely be switching to a smaller/milder camshaft. If that means that the car runs out of breath at 6000 rpms, who cares? I have 3 speeds in the trans and the GV overdrive. The GM BOP and Cadillac engines had long stroke cranks and they made huge torque numbers. they often only had 3.42 gears or taller to move those 5000 lb behemoths around, too. A milder cam means I could use a stock type stall rated converter and maybe switch to a 3.55 diff. I think I'm ready to have a more streetable car instead of a 6500 rpm dragstrip engine.

[Challenger340]

Strange thing: Adding the Rev-N-Nator ECU made my A/F ratio go rich at cruise. I would have expected the thing to make the engine run cleaner due to it being a "better" unit.
I welded in the H pipe. I would have done an X but I don't have a way to make one of those. Anyhow, the exhaust tone quieted down some. It sounds less raspy than before at idle and at freeway speeds. I like that but I'm not finished yet.
The soggy feel at part throttle still annoys me. This is the result of using a high stall torque converter, OD gearing and a "race" oriented camshaft. If I ease into the gas at freeway speeds, the car feels lazy. If I lean into it harder, the car responds great.
I think that I am to the point where the rough idle and high rpms are too much for me. I want instant throttle response. I want to tap the gas off idle and start moving right away. This means I'll likely be switching to a smaller/milder camshaft. If that means that the car runs out of breath at 6000 rpms, who cares? I have 3 speeds in the trans and the GV overdrive. The GM BOP and Cadillac engines had long stroke cranks and they made huge torque numbers. they often only had 3.42 gears or taller to move those 5000 lb behemoths around, too. A milder cam means I could use a stock type stall rated converter and maybe switch to a 3.55 diff. I think I'm ready to have a more streetable car instead of a 6500 rpm dragstrip engine.

It would seem that by now ?
.... that you are fairly conversant with all aspects of DCR as it relates to detonation and fuel requirements.
So fill ur boots with the smaller Camshaft if you are so inclined.

The one question I have, is what makes you sure that you currently have a 6,500 rpm Dragstrip Engine ? or, that the new "smaller" Camshaft you are planning will make peak power anywhere even close to 6K ?
I guess what I am asking is.... have you ever Dyno'd this Engine... as in an ENGINE DYNO.... to SEE the actual peaks ?, with Lambda, EGT, A/F, Fuel Metering,, etc., etc., for tuning ?
or,
what are your 6,500 and 6,000 rpm numbers based upon ?

just curious, but HOW LONG have you been chasing this DETONATION problem ?
I did not go back and re-read your entire commentary on this problem, but if may also ask at this late date ?... what were the Flow numbers on your Ported Edelbrock Heads used on this 493, and more specifically..... what is your final "Intake Port CC Volume", as it relates to chasing this confounding detonation problem ?

To Wit here;
Just checking to be sure here ?......but have you have been chasing DCR/Camshaft/Detonation problems all along, with un-ported stock Edelbrocks on this 493 ?  

[Kern Dog]

In 2006 I had the car on a chassis dyno. It had the 292/509 cam in it then. I had the same Performer RPM intake, 850 Demon carb, 2" TTI headers as I still have. The cam was degreed in and set 4* ADV. The car peaked at 369 HP at 5350 and the torque was in the 490 range at around 3100 rpms. I clearly recall the HP numbers but not the torque #s. As many other first time dyno test participants, I was disappointed and annoyed. The car detonated even back then, but the 4* ADV had the cranking compression at 200 ! Later I moved the cam back to straight up ( What I call dot-to-dot). The cranking #s came down to an average of 188 and the car stopped knocking. Many miles later, the detonation came back. (Probably as carbon built up on the pistons)
I have not had the car on a dyno again to verify the results of the changes.
I picked the 6000 & 6500 rpm number out of thin air....I may be being conservative as to "over-revving" the engine. Oil pressure is always good. I have no valve float. Even at 6000 the engine is still gaining at a fast rate. Who knows, this engine may still be making  power past 6500. I just feel nervous running it that high.

Your last question: How long have Ibeen chasing the detonation?
Since the original assembly in 2004 I have been dealing with it from time to time. It was only evident at WOT so I could have simply driven around forever at 3/4 throttle or less and never had a problem. When I had it on the chassis dyno, the operator tech recurved the distributor and eliminated most of the knocking. Later in 2006 I switched cams and added thicker .060 Cometic head gaskets. The detonation stopped completely but the new Comp cam went bad. I replaced it but the second one went bad as well. I decided at that time to save a few $$$ and put the 509 cam back in. It turns out the 2 failed cams pushed lifter shavings through the engine. I had some valve stem wear and had to pull the heads. I didn't have the money for another pair of Cometics so I used some Fel Pro gaskets I already had. The engine ran fine again until carbon built up again.

[Kern Dog]

To recap the events of the past year:

After a 1000 mile round trip last Spring, I decided to get serious about eliminating this detonation problem. I had pulled the engine in 2011 to hone and rering it, so the long block was sound. Plenty of people suggested i replace the MP 292/509 cam with a modern grind with a later intake closing. A guy on FABO suggested a Lunati solid flat tappet that he liked. I installed one and my detonation problems got worse. I later discovered after digging that the Lunati had an IVC that was 1.5 degrees earlier than the 509. The cam swap was a backwards move!
I tried recurving the distributor, jetting the carb, checked fuel pressure, retarding the timing and race gasoline. The only time it did not knock at WOT was with 110 leaded gas and one other time when I retarded the timing to 20* total. I had 191 average cranking compression, almost 11.0 CR and a dynamic CR of 8.29. I tried the suggestions of those I deemed to be smarter than I. Finally I defaulted to using thicker head gaskets again. While the heads were off, I had them ported. I did not have them tested on a flow bench. The pistons (once cleaned) showed absolutely no signs of detonation. This may be because each time I heard the engine knock, I always lifted off of the gas immediately.
I'm now down to 10.07 CR, a dynamic of 7.61 and the engine does not knock. Currently I'm pondering how to get it to feel more responsive at freeway speeds around 2500-3000 rpms. I think with a 4 degree advance of the cam and widening the lash a bit, the car will feel a bit more snappy. I'm also leaning toward getting a tighter torque converter.

[heyoldguy]

There are only a few people who have responded to your threads and know how to put a complete package together to do what you want successsfully. Bob does. If Challenger340 offers advice, don't mix his recommendations with anyone else's advice. You have received information from too many sources that haven't really been there and done that. I told you once before, select one person who knows what they are doing and let them advise you.

[Cooter]

I'm convinced with my iron headed 440 @ 10.8:1, that even todays "premium" fuel is just sh*t.
Mine has nowhere near the overlap of your cam but still a bit and it rattles.
Put true 100 octane in tank and no knock.
I even calculated out the .040 'quench' BS...still rattles. Even with aluminum heads, best to play it safe and stick to 10:1 on iron heads, and no more than 10.3:1 or so with aluminim heads.

Newer cars can get away with it due to electronics, but old school motors just can't.

[Challenger340]

You still, really, have NOT answered the most important question regarding the useage of Edelbrock rpm heads on a 493, as it relates to your entire DETONATION problem !!
Which I suspect, is only compounded with bigger Camshafts ? because if the Port Fawks up and goes sonic at "x", no amount of bigger and tuning will fix it.

Having them supposedly "ported", without any idea of Flow or CC Volume of the Intake Port means absolutely nothing, again, related to the DETONATION PROBLEM.

You can Tune until the Cows come home, jetting, play with DCR/Camshaft, etc., etc., attempting to get around the Detonation, which sounds like you did here ?
And unfortunately,
it will all be for nought, as you found out..... because, THAT ain't the problem, as if you haven't already figured that out by now ??
The PORT is the problem !
(light bulb going on here )

Get your Heads in somewhere WITH A FLOWBENCH !
IMO,
You can NOT run 250 cfm Edelbrocks anywhere even close to attempting mid range DCR/pressure Calcs on 91 Octane on a 493.
and IMO,
THAT HAS BEEN YOUR WHOLE PROBLEM ALL ALONG !!!

And as heyoldguy said, and very well put I might add, get one guy who KNOWS WHAT HE IS DOING helping you... stick with it.
Come to think of it...
If you are going to continue with the Edelbrocks....   might be a REALLY good idea to get your Heads over to heyoldguy for some Porting, Flow Data, before going any further with anything !

I am OUT,
my apologies if I have offended in any way,  by the manner in which I have presented this... NOT my intent !!
IMO, just needed to cut to the chase here  The PORT is the problem... always has been !

[Kern Dog]

I don't understand anything that you wrote. Your posts remind me of this really smart Carpenter I worked with that was always willing to help others, yet spoke over everyones head. I appreciate that you responded, but after reading it twice, it still isn't that clear to me.
Ports being the problem? Considering that this is the biggest inch/biggest money engine I've ever built, I'll readily admit to not knowing everything that there is to know about making it all work to its potential. The reference to intake ports may be correct, but I have never heard anyone else mention that. I don't see how intake ports have anything to do with detonation.
I have ran it with several different combinations since 2004. The only instances where it didn't knock was when it was ran with lower static compression. Once with .060 Cometics in 2006 and the way it is now.
I thought the Edelbrock heads were rated at 291, not 250. Regardless, they are supposed to outflow any stock head except for the Max Wedge heads. In all the responses in all the threads that I have started, several guys claim to run 906s and 452s that surely flow less than stock Edelbrocks. The guy that ported mine is a friend of the Machinist that I use. He is an old school guy that probably has no access to a flow bench. I've never had heads ported before so I went on the word of the Machinist that hasn't steered me wrong before. Maybe the heads aren't "documented" to flow any better than before. I'm not pulling them off the car to get validation of flow numbers.
The car isn't knocking anymore. THAT was the main goal. Now I'm casually working on improving the street manners.

[Cooter]

See the problem IMO Red 70 with guys that know more is we tend to get really frustrated when people will choose to listen to the furthest possible opinion on their problem. It's the Internet and when a question, or response is asked/given on a forum it took me years to get over the fact that some folks will pick and chose the stupidest reply to follow cause they simply do not like the guy that while correct, he's an ass.

What I hate to see are those that simply reply "just send your sh*t to me, pay me, and I'll get you right"...
These types clearly do not understand that this is the Internet and people want/ask for FREE advise, NOT A SALES PITCH . Hense, my signature.
while I replied in the beginning that I felt the only way your gonna get it to stop pinging is lower the static compression, you chose to do all sorts of stuff before finally lowering compression.
yet, I'm sure their are a few here that might be able to get your motor to NOT ping, but if they are gonna want to charge for their help, I'm sure you feel the same as me, they can eat sh*t and die. We are here to help, not pad some douche's pocket. I don't care how many times he's been there, done that. If your not willing to help for free here, GTFO.

What you just experienced is what I've delt with for about 10 years on another board. People there clearly could see I'd been where they are, yet refused to stick with one person's advice and were all over the place. What I had to learn was some people have to get hit by that perverbial train. They refuse to listen. It stopped bothering me about 4 years ago. Some threads I read and while pissed poor attempts are made to make me look as if I didn't call it, the knowledgeable can clearly see a reply that's worded different, but the same EXACT thing I told them. They wanna go round In  circles, f*ck em. Let em.
this does frustrate the knowledgeable, but it took me a long time I to understand, no matter how many you help, people are NOT gonna listen every time. I wasn't even attempting to charge for my services either.

When the knowlegable feel frustrated, they tend to blow you out the water with tech. Talk as you've whitnessed here, or they know the answer you seek and since they can't run a business, they just refuse to help you and will watch you struggle.
there's a special place in hell for these types IMO. Carry on, and if you figure out some other way of cutting back on the ping, let us know, cause we like results and are appreciative.

[Cooter]

Don't belive me? Take a look at the "Charger Build Question" thread.....

[Challenger340]

I don't understand anything that you wrote. Your posts remind me of this really smart Carpenter I worked with that was always willing to help others, yet spoke over everyones head. I appreciate that you responded, but after reading it twice, it still isn't that clear to me.

Look, and excuse me ....
But, I am stating it as best I can here ?
Trying to explain a concept... is never easy ?

In the SECOND SENTENCE of my reply, I put it as plainly... and simply... as I can ?
I Said...
"if your Port FAWKS UP.... and goes SONIC....  no amount of Tuning with fix it"
To clarify.... in my experience....
When a port can NOT maintain, or keep up.... to transfer the Air/Fuel Charge from the Intake into the Chamber... that A/F Charge "quality" suffers, resulting in erratic Flame Fronts, typically heard as ping.... ping.... ping.... due to poor A/F charge quality in the chamber..... after the Fuel having been SEPARATED FROM THE AIR in the port.
The Port going SONIC, refers to the audible noise heard on a FlowBench when this happens... basically, a separation of the AirFlow in the Port, including separation of the Fuel Molecules from the Air, an IN-EFFICIENT Port.

IMO,
Your Head "Ports" are insufficient for the application, either due to Size, Shape, Flow, or Efficiency, and it is resulting in very poor quality Air/Fuel being presented for Ignition in your Chambers.
In my experience,
You can NOT Tune around this condition, you NEVER WILL Tune around it, there is NO WAY to Tune around it.

IMO,
THAT has been your problem all along here, consistent with the symptoms

* Thick-Gooey Carboned residued Piston tops.... that's the lower ended Oils that do Not burn well.... separated from the upper end aromatics in the fuel(they do burn)...... which crack off in the distressed IN-EFFICIENT Ports when going Sonic.
It rips the fuel itself apart, for lack of better descriptive here.

* Glazed Cylinder Walls, something is lubricating from ABOVE the rings now isn't it ?
I will bet I could SHAVE with the underside of your 2nd Rings which will be sharp as a razor !

* The Engine is over sensitive to Fuel Octane quality far beyond "normal" DCR ranges for lower Octane Fuels ??

* Tuning "irregularities" seen wide-band.... where it seems to AVALANCHE, or "over react" all of a sudden to changes one way or the other ? under the wrong conditions for normal explanation ?

I am NOT trying to speak over your Head.... no mileage in this for me ? But honestly here.. have you not SEEN all of the above ?
But,
I also can NOT use up gunga bandwidth trying to explain thermal dynamics and airflow over the internet ?

IMO,
GET YOUR HEADS FIXED !

Good Luck with the Engine
Bob.
 
 

[cudaken]

Greg, while sometimes Bob and Cooter may not have the best Keyboard manners I do respect there ideas.

I have had a few Cam 2's and I do understand what Bob is telling you. I had a local Mopar expert port my 346 heads for the blower motor. Before he gave them back (he worked in is garage at home) he took them to have them bench flowed by his friend. Told me the gas and air was not mixing right and had to play with them a little more. He said it would make the A/F mix lean, and with a Blower it is a bad thing. 

I all so think what Bob is stating is there is a differences between Flow and Air Fuel Mixture. Am I right Bob?

Cuda Ken
   

[Kern Dog]

Look, and excuse me ....
But, I am stating it as best I can here ?
Trying to explain a concept... is never easy ?

IMO,
GET YOUR HEADS FIXED !

Good Luck with the Engine
Bob.
 

Thanks Bob for responding. I do understand you better now. As I wrote before, the engine isn't knocking since I changed to these thicker head gaskets. I am not going to remove the heads again anytime soon. The engine ran great before with the Edelbrocks UNported with .060 Cometics and it runs great with ported heads and these .075 Cometics. I appreciate your concern, but if the goals I had have been met, I see no reason to fix what isn't broken.
Oh, the cylinder walls are fine, my cranking compression is a 191 average and each cylinder is within 3% of each other.

[Kern Dog]

I replied in the beginning that I felt the only way your gonna get it to stop pinging is lower the static compression, you chose to do all sorts of stuff before finally lowering compression.
I must admit that your advice wasn't what I wanted to hear but it did make the difference.


Carry on, and if you figure out some other way of cutting back on the ping, let us know, cause we like results and are appreciative.

Again, your advice was correct. The car has been ran several times since I got it running again and it does not knock on 91 octane. Warmer weather is coming but but I hope I'll stay knock-free.
I hope that threads like these serve as a guide for others to read. Maybe some of my mistakes can be avoided by others in the future.

[Challenger340]

I all so think what Bob is stating is there is a differences between Flow and Air Fuel Mixture. Am I right Bob?

Cuda Ken
   

EXACTLY Ken,
and Thanks for putting it so simply.

[Kern Dog]

Strange thing: Adding the Rev-N-Nator ECU made my A/F ratio go rich at cruise. I would have expected the thing to make the engine run cleaner due to it being a "better" unit.

I wrote this a few days ago. Today I went out to resume tuning. I was curious about why the car was running richer than it was before. I replaced the #84 primary jets with #83s. I adjusted the 4 idle mixture screws to get the in gear idle #s to the 14.4-14.8 range then went for a drive. The A/F numbers were a little leaner than before but I had expected there to be more improvement. back at home I pulled the Rev-N-Nator and installed the MP Chrome ECU. The numbers didn't change much. if at all. It was then that I realized that I had retarded the timing 3 degrees with the REV unit as per their instructions. I reset the timing and the A/F #s improved. I realize now that the ignition timing change was responsible for the change. I didn't know that timing had such an effect on the readings.
The car really scrams. The lazy part throttle feel seems to have diminished. It feels much more snappy. I'm going to add vacuum advance to see if the A/F at cruise improves even more. I expect it to help.

[Kern Dog]

Today I finally checked the cranking compression.
Before with the Fel Pro .039 head gaskets and nearly 11.0 to 1 compression I was at an average of 191. Now with the 10.07 to 1 ratio my average went down to around 160 !
I checked every hole twice. I had the battery charger on the battery to maintain an even charge. I was amazed that the cranking numbers dropped off so much compared to before.
I decided to start playing with the lash to see what effect it had on the cranking psi. Wow, what an eye opener! The Hot Lash specs are .020 IN and .022 EX. I normally set them .006 tighter (.014 & .016) when cold to account for the expansion of the aluminum heads. This time I set them cold to .022 IN and .024 EX. That is .008 wider spec. This raised the cranking compression to an average of 170.
I haven't driven the car yet. I figure I'd see how it feels after the lash adjustment. If it feels more responsive down low I might leave it as is as long as it isn't knocking.
I was really surprised to see what an effect the lash really had on the cranking compression

[Kern Dog]

On another site, a Mopar guy thought I may be heading for trouble with the wider valve lash setting. On his advice, I called the Lunati tech line. Their guy agreed, saying NOT to go more than .004 past the published spec.
I decided to try advancing the cam 4 degrees instead. This is supposed to move the power band lower in the rpm scale.
I finished up today. The timing was reset to account for the 4 degree cam advance. It fired up quickly and once it was warmed up, it seemed to idle smoother. I did go back and relash the LH bank to the spec on the cam card. I figure it makes more sense to do one change at a time so I'll know exactly what effect each change has. It was raining this afternoon so I have yet to road test it.
I didn't put a vacuum guage on it. I just didn't think of it until I started writing this just now. The idle speed went up about 100 rpms.
Along with trying to make the car more civilized, I'm still working on the Air/Fuel ratio tuning. Now that I have the MP Chrome ECU back in I'll probably go back to using vacuum advance. I'm sure that will improve the burn cycle at idle and cruise speeds

[Cooter]