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Author Topic: 1968 Charger RT 440 Initial and mechanical timing help  (Read 544 times)
garthed
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« on: August 28, 2022, 05:01:09 PM »

Hi everyone,

I have a 68 Charger with a 440 that was rebuilt about 20 years ago. I have been chasing down a pinging and or detonation issue forever. I don't have the specs on the motor as a mechanic I had working on it lost the build sheet on the motor long ago.

Motor probably only has about 10k miles on it.
440 Rebuilt
Auto
Edelbrock carb
Was told it has 11:1 compression
Large cam but do not know the spec
Roller rockers/ hydraulic lifters
Hooker Comp headers
Electronic ignition with the orange box/ not sure of brand of distributor but looks like the standard distributor kit you get at summit.
Not running any vacuum advance.


Ok for the issue

Between 1800ish to 2700ish rpm I get pinging under load some times at full throttle other times at just half or less. Above 3000 I either don't hear it or its not happening.

Initial timing is set around 20-23 at about 900 rpm using a vacuum gauge. Set to highest vacuum and then back it down just a bit. 

Total timing seems to come in early at around 1800 rpm and its around 35.

Running 100 octane (at $9.99 a gallon ouch) I've tried octane booster and 91 but the pinging is really bad then.

If I'm just cruising around under 2k its ok or if I accelerate past lets say 2500 slowly it fine.

I'm wondering is the total/mechanical timing to much and if so how do I fix this? Or is the total timing coming on to soon causing it to ping early, and if so how do I fix that? With springs, if so what springs should I buy.

Also someone told me that I should try colder spark plugs to fix pinging.  Not sure what plugs I'm currently running.

The carb is stock and basically new. If I lower initial timing it will still ping at 1800-3000 RPM and also runs really hot.

Any help is greatly appreciated. I'm not looking for it to be a race car. Just run and drive with out the pinging.

Thanks
Garth
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metallicareload99
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440, 4-Gear, 3.54


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« Reply #1 on: August 28, 2022, 08:57:39 PM »

What cylinder heads and spark plugs? Unless you are using domed pistons getting to 11:1 is kinda difficult shruggy
My 440 when it had iron heads would ping like yours at low RPM with some load on it. I ended up having to drive around it, I.E. wait until after 3,000 RPM before getting on it etc.
I think your initial timing is ok. Slowing down the curve might help. Even though you already tried taking out some total timing that might help, if you can live with that. If you have vacuum advance I figure you might as well try and use it?
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1968, When Dinosaurs Ruled The Earth
b5blue
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« Reply #2 on: August 29, 2022, 07:46:20 AM »

Sounds lean, try upping jetting to larger. Without pulling the heads your kinda spitballing a fix.  2thumbs
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mally69
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« Reply #3 on: October 13, 2022, 04:53:53 PM »

Well if your running 100 octane and its pinging, you either have your total timing to far advanced or your compressiom is higher than 11:1.  What is your total timing ?  To check your total timing screw your throttle adjuster up until engine is at a constant 3k rpm. Check it and see what it is.   Report back
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mally69
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« Reply #4 on: October 13, 2022, 05:00:09 PM »

Then while its revved to 3k turn your distributer until the engine runs at its smoothest point thats manipulating the fuel burn, lock it down there. But if yiur mixing 100 octane with other fuel youll be adjusting every time u fill it ul because the ratio wont be the same.  See it it pings then. If its straight mix of 100 you should be okay once its set. But 11:1 with iron heads and 100 oct should not ping unless its to far advanced. Tje reason for 3k room is to make sure your advace weights inside dis are fully advanced.
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