spark plugs for mild 440 w iron heads?

PurpleBeeper said:

I don't think colder plugs would help you even a little bit. Your "pretty high compression" means you need better gasoline and if you built a 12:1 compression motor, then you need race fuel.

Your initial + mechanical advance is not excessive, so another possibility is that your vacuum advance canister is giving excessive vacuum advance. You can reduce the vacuum advance by sticking a tiny allen wrench inside the hole on the vacuum canister where the vacuum advance line attaches. I forget the size or which way adjusts up/down.

One final possibility is that you have excessive carbon buildup on the pistons. You can check with a $30 boroscope down a spark plug hole. SeaFoam works pretty well to remove carbon.

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RedHot67 said:

Hi,

I have a mild 440 HP (1971 engine) in my 65 Coronet and was wondering if a step colder plugs than a 85 Autolites would bring down the heat a bit?

Another problem I have is pinging with vacuum advance hooked up and timing set 7° BTDC. Mechanical advance is limited at 19°. Shouldnt be pinging right? Maybe the right plugs can cure it, not sure though.....

Specs:

MSD ready to run
2 1/2 headers
EDE performer
iron heads
680 Quick Fuel vs
+pretty high compression..

THX in advance and all the best from Europe,

Dan

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Dennis H said:

N G K's.

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moper said:

Plugs have very little impact on the tendency to go into detonation or ping. I'd bet the ping is because it's lean, either in light throttle cruise or tip in. Get a vacuum gage and tape it to your windshield, then go for a drive. Note the vacuum reading at idle, what that vacuum does as you press the gas, what the level is during light throttle cruise, and as you transition from light throttle to wide open. Then take a look at the power valve and jetting in the carb.
I don't feel plugs will help - this is a carb tuning issue.

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