im getting mad ping
so far ive bump the timing A/R.
turn the screw in/out of the vac/advan. can

Can /will someone please give me a run down of ALL the facters that will cause pinging.


heres my combo
.0075 off head stock head gasket/pocket ported
.447 lift cam
orange box with new 79 /6 dist.
500 cfm.eldorbrock/header

Is that supposed to be .075" off the head? .0075" is less than a normal 'clean-up' pass.

What is your initial timng set to? Do you know how much mechanical advance you have?

Have you tried disconnecting and plugging the vacuum advance line (temporarily, to see it the pinging is affected).


main factors that can cause pre-detonation (pinging) include:

1 - Timing too advanced
2 - Too-high compression ratio
3 - Too low-octane fuel (goes hand-in-hand with #2)
4 - Combustion temps too high (a result of any or all of the above)

-S/6

_________________
The "Silver Bullet"
87 Ram D150

5. Fuel/air mixture too lean (improper carb calibration, fuel pressure too low, vacuum leaks)
6. Incorrect spark plug heat range installed (what are you running?)
7. Improper cam timing (installation error, too far advanced)
8. Cylinder head gasket obtrusion into combustion chamber, forming glow point for preignition of fuel (not usually an issue unless engine is overbored)

...left out 9) burning oil which lowers fuel octane, often caused by dry/non-existant valve seals and/or worn guides.

Probably not your problem, though if the head has been freshened.

D/W

_________________

If it ain't broke, fix it!

Interesting that you mentioned that. When I got my /6 block back, bored .060", the machine shop rechamfered the tops of the bores (which I did not want them to do). My steel shim gasket protruded slightly (a few thousandths) into the combustion chamber, so I rigged up a sanding drum out of a pint can to go on the end of a drill and trimmed back the gasket the required amount, thoroughly deburring it when I was through. I had forgotten all about that little trick until you brought that up re preignition above. Hope this helps somebody.

D/W

_________________

If it ain't broke, fix it!

GREAT guys..
this gives me a GOOD check off list.
yeap .075 off the head.
i using autolites for an 87 dodge /6 not good???(should i try running another plug?

thanks alot

well,,,i richened the A/F mixture and that seemed to have help alot.