440 combo opinions

[firefighter3931]

I did make a riser for the throttle cable to be in line, so at least I did that properly. 

Yep, you sure did...good job ! 

It'll be interesting to see what you find out looking down the throat of that carb with a helper matting the gas pedal. 



Ron

[thrillbilly]

I did make a riser for the throttle cable to be in line, so at least I did that properly.

Yep, you sure did...good job !  

It'll be interesting to see what you find out looking down the throat of that carb with a helper matting the gas pedal.  

Ron

I remember fooling with that, and getting it to wot and not hanging the idle open wasn't easy.  I didn't notice anything in the demon instructions about it.  But at least that will be one thing eliminated.

[firefighter3931]

The instructions leave a lot to be desired...it's not specific to Demon either ; Holley is the same way. These Carbs are "universal fit" so one size fits all....but there should be better information for the end user.  

They make those adapters for a reason and they are brand specific because the pedal ratio is not the same between Ford or Chrysler or GM.

I made the same mistake some 30 years ago installing my first Holley double pumper. Fooling with the throttle cable lockdown I could adjust the cable for WOT but it was partially open at idle. When I readjusted it to close at idle it would not fully open at full pedal. I thought for sure the carb was defective and returned it to the speed shop for replacement. The counter guy understood what was going on and ordered in the throttle adapter for me and all was good.  



Ron


Ps. With that engine combo it's going to like the 850 Demon double pumper....I wouldn't hesitate bolting it on. 

[thrillbilly]

The instructions leave a lot to be desired...it's not specific to Demon either ; Holley is the same way. These Carbs are "universal fit" so one size fits all....but there should be better information for the end user.  

They make those adapters for a reason and they are brand specific because the pedal ratio is not the same between Ford or Chrysler or GM.

I made the same mistake some 30 years ago installing my first Holley double pumper. Fooling with the throttle cable lockdown I could adjust the cable for WOT but it was partially open at idle. When I readjusted it to close at idle it would not fully open at full pedal. I thought for sure the carb was defective and returned it to the speed shop for replacement. The counter guy understood what was going on and ordered in the throttle adapter for me and all was good.  



Ron


Ps. With that engine combo it's going to like the 850 Demon double pumper....I wouldn't hesitate bolting it on. 

I agree, I really think it will like more carb also.  I real do appreciate the the advice, that's all I was looking for.  You look at something for so long, you just overlook things.

[firefighter3931]

I agree, I really think it will like more carb also.  I real do appreciate the the advice, that's all I was looking for.  You look at something for so long, you just overlook things.

You're welcome....hopefully we're headed in the right direction 

Sometimes it really helps to have a second set of eyes when troubleshooting. Often the correction is right in front of our eyes and we don't see it. Been there...more than once ! 

Keep us updated 



Ron

[thrillbilly]

I finally got down to the car.  Couldn't find the receipt, but I am getting 175 psi on the compression tester.  I am getting wot with the throttle setup that I have.  Sorry for the long wait, and thanks again.

[c00nhunterjoe]

Those are quite respectable cranking compression numbers. Will have to look up ic ° for your cam, but that should be upper 9s to low 10s static. Given the other known components on your engine, your 100 mph trap speeds definantly sounds like either fuel starvation or lack of wide open throttle.

[thrillbilly]

It is fully opened at wot, we checked it today.  More cfm or go to an electric fuel pump setup?  Will a too small of a carb run rich at idle and cruise and lean at wot due to lack of air flow?  Or am I way off in that thinking?

[BSB67]

........your 100 mph trap speeds definantly sounds like either fuel starvation.........

Maybe this.

[BSB67]

More cfm

or go to an electric fuel pump setup?  

Will a too small of a carb run rich at idle and cruise and lean at wot due to lack of air flow?  

Or am I way off in that thinking?

No.
No.
No.
Yes.

It sounds like you have a problem somewhere.  If this is correct, find the problem and fix it verses just replacing stuff.  That is what I would recommend.

If you really want to get the engine to make the 450+hp it should and the car run the 110 mph that it should, you should do the following.  1) put a fuel pressure gauge on the car that you can read while you are driving and make sure you have at least 3.5 psi at WOT (if not, find out why), 2) Tune the car, 3) go back to the track and make several passes with and without the mufflers on.  Record weather data.  4) Report back.

Alternatively, if you just replace stuff, the problem might just go away.  This is fine too, but could cost more, and you really won't learn and understand what the problem is.

[firefighter3931]

I finally got down to the car.  Couldn't find the receipt, but I am getting 175 psi on the compression tester.  I am getting wot with the throttle setup that I have.  Sorry for the long wait, and thanks again.

The 175 psi is good news ! I was hoping to hear that the throttle wasn't fully opening but that would have been too easy 

I'm still thinking it's a fuel related. As mentioned above....a fuel gauge that is readable inside the car while going down track would answer a lot of questions. 

Something else I've seen in the past is a broken torque converter scrub a lot of MPH. If the fuel system checks out that's where to look next. 


Ron

[thrillbilly]

A fuel pressure gauge inside is something I don't have, but easy enough to add. 

[XH29N0G]

I have a question related to your question about Rich/Lean with carb size (I agree with BSB's response) and related to an earlier comment you made about it always running very rich.  I apologize if I missed it, but what does your fuel curve look like?  What do your plugs look like?  From one of your earlier posts, I take it that have a wideband AF gauge. The others on here will know better than I, but I believe you also would see fuel starvation with that.   I appreciate the car has not been running and this information may not be available, but if it is, it might be relevant.

[thrillbilly]

Yes, I do have a wideband.  The electrode of the plug is pretty clean, but the rest of it is black from being rich.  I'm not sure what you mean by a fuel curve?  I can data log with the wideband I have, but have never done so.  Is that what you mean?

[XH29N0G]

I'm not sure what you mean by a fuel curve?  I can data log with the wideband I have, but have never done so.  Is that what you mean?

Yes, that is what I meant.  I thought knowing what the A/F looked like as you run it up through the gears at WOT as another type of information that could be relevant.

[BSB67]

In re-reading my post, I want to make sure my point is clear.  Before you look for more power, get what you have to run right.  A bigger carb will make more power, but let's find the missing 80 - 100hp first.

Carb size has nothing to do with lean or rich.

A plug can actually read black for different reasons and conditions.  Once the non-elcctrode part of the plug is black, it always will be.  Based on you level of knowledge, I don't think you should be drawing too firm of any conclusions based on what you have described with your plugs.

Put a fuel gauge in it, as close to the carb as possible and do some full rpm blasts and report back.

As mentioned, converters, and other things can suck power.

[thrillbilly]

I probably should have logged some data, but it felt to fast and furious to have a lap top hooked up,  :lol:but it would have been a big help for this discussion.

I'm looking around for a fuel pressure gage.  What is a better setup, a mechanical or electric setup?  My fuel inlet does have a threaded port with a little mechanical gauge, but isn't doing me any good if I can't see it while driving.  I won't change any parts until I can get these readings.

It will probably be a month or so until I can report back.  I wait until all the nasties are off the road before I get it out.

[BSB67]

My fuel inlet does have a threaded port with a little mechanical gauge, but isn't doing me any good if I can't see it while driving. 

Got a GoPro?

[thrillbilly]

No, but I could borrow one.  Oh duh, that's a great idea.

[c00nhunterjoe]

You dont need anything fancy, a simple mechanical gauge routed up to the windshield and ziptied to the wiper arm is more then sufficient for the required test.

[thrillbilly]

True, they are expensive, and I'm not sure it's a gage you constantly need?

[c00nhunterjoe]

True, they are expensive, and I'm not sure it's a gage you constantly need?

20 bucks is not expensive. Like i said, you dont need anything fancy. This basic gauge setup is housed under dozens of brands and available in stock at almost every national auto parts chain, some walmarts, and just about everywhere in between.
http://www.amazon.com/gp/aw/d/B00KRJFSFQ/ref=s9_top_hm_awbw_b13uDV_g60_i2/185-1736852-1202533?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=mobile-hybrid-11&pf_rd_r=0Y1AYG938F0F475DP1CH&pf_rd_t=30901&pf_rd_p=bc078692-2358-593e-99ee-92c15149bb20&pf_rd_i=15707421

[thrillbilly]

I guess I'm totally overthinking what I should use.

[BSB67]

http://www.amazon.com/Chrome-White-Face-Pressure-Gauge/dp/B00TST7YHQ/ref=sr_1_3?s=automotive&ie=UTF8&qid=1457311101&sr=1-3

You can get these anywhere..  I think AutoZone or Advanced Auto carry the Mr. Gasket gauge with tubing and fittings.

[c00nhunterjoe]

  yup, more then one way to skin a cat. Like i said, aint gotta be pretty, just has to work long enough for a few full throttle blasts.