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Discussion Starter #1
what exactly does pinging from too much timing sound like? my timing has been set @ 40* in my 68 for awhile and ive never heard anything abnormal. what should i be listening for?

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I think 3 rocks rattling around in a coffee can is about the best sound description I have ever heard. However, you can have detonation and not hear it.

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375hp 78 Chevy truck
77 Chevy Nova
95 Chevy Lumina 3.4L
and building a 78 Nova
 

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Jvolk81, check your plugs. If your detonating, ther will be speckles or dots so-to-speak on the porceline of the center electrode. If you don't see any it still doesn't mean it's not pinging, just much less likely.BTW, is Volk your last name? Just curious, that's my mothers maiden name.

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jvolk81, perhaps you have heard this noise only it was called spark knock or valve rattle. Set your timing up 4 more degrees and drive uphill. THEN you'll know!

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67 Nemesix
 

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Discussion Starter #6
ummm well see thats the thing, ive never heard any noise and the other day i realized that my distributer had moved and the timing was closer to 50* (i have 10.5:1 comp) and i didnt remember hearing anything strange...is this noise loud? could i have possibly just missed hearing it...im pretty sure i should ahve heard something with the timing that advanced, especially on a full throttle run or two

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You may hear a rattle at startup or part throttle under a load (like lugging it up a hill). I know you have had to hear a car go around a corner and give it some gas and rattle, ping and knock or had an old caddy pass you on a hill making the same racket.

If your car is loud it will make it harder to hear. Are you using vacuum advance? At what RPM are you getting 40 or more degs advance? Is that with the vacuum disconnected and plugged?

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...Dennis
"The '69, the '96 & the club"
 
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You must be running premium w/octane booster. Pinging is primarily octane related w/timing second.

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67 Nemesix
 

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what are you running down the road with
what does the tach read,
40 degees.wow take the dist out and realighn the timing marks,drop dist back in
dead on.check the book.IF REQ
40 degrees sounds like your motor has
high lift and duration as well as overlap
and cam lobe degrees.


pinging is piston knock,yeah sounds
like marbles in a can ,it is caused by detonation in the cly ,there are areas on the piston that are carboned up that cause the secondary ignition/detonation/flash.
decarbonize the motor,yes higher octane
allievates the problem only cause it burns faster,less burn time.
advance the timing masks the problem .
some people mistake timing chain rattle
noise with pinging.
yes going up hill is a good test tool.
fix it the right way..................
 

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<BLOCKQUOTE>quote:</font><HR>Originally posted by DjD:
If your car is loud it will make it harder to hear. Are you using vacuum advance? At what RPM are you getting 40 or more degs advance? Is that with the vacuum disconnected and plugged?
<HR></BLOCKQUOTE>

Just looking to help!
 

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So it wasn't hooked up when you checked it. With it hooked up you should be able to make it ping. With 40degs or more total and a stock vacuum canister you can expect 60 degs + at part throttle. If you can't make it ping by lugging the engine in 4th on a hill and rolling into the throttle some then something isn't working properly or your engine is very low compression and designed to run on low octane.

Detonation and preignition are 2 different animals. Detonation occures when the spark ignites the fuel and trys to send the pistion back down on the power stroke before it reaches TDC. Preignition (engine run on) is cause by fuel leaking into the chamber (high idle), carbon build up (burning carbon acts like a glow plug) and excessive cyl temps. If reducing timing solves run on then most likely the problem was high idle.. I digress.....

Tell us about your combo! Stock, modified, compression, carb, heads, cam spec etc. As much as you can. If it's running good we may be chasing our tails. 40 degs total isn't unheard of but 50degs is another story...

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...Dennis
"The '69, the '96 & the club"
 

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Discussion Starter #14
alright, heres a recap...timing was almost 50*, as far as i know if spent a whole night beating on it and never heard any pinging. The vacuum advance was not hooked up during this time. I retarded the timing back to 40* then connected the vacuum advance...drove it for a little while and all seems fine. this is the confusing part. im pretty sure i should have heard pinging when the timing was around 50* because of my setup but i never heard any.

396 11:1 closed chamber pistons with cast iron open chamber square port heads
Stock rods and crank
.290 dur. .544 lift
93 octane gas

Just want to know why i never heard anything and the spark plugs all look fine.



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