Spark plugs and HEI

mbalbritton

mbalbritton

#@$%!
Joined
Mar 22, 2005
Location
Lakeland, FL
Anyone have experience with seemingly premature failure of spark plugs? Theoretically due to an HEI distributor upgrade.

I'm running an HEI dizzy on my AMC304. I've gotten an estimated 8-10k miles +\- out of the last two sets of plugs. I run ACDelco R44XLS plugs gapped out to about 45. The ones I pulled today looked good on the electrode end, but two of the plugs had cracked and busted insulators on the plug wire end.

Just spit balling, but wondering if the higher voltage of HEI is wearing them out, or why the plugs seem to be failing prematurely.
 
I don't think the higher voltage is damaging the plugs directly, but I have a feeling that you're getting a more complete burn and are possibly now running leaner, or maybe having some detonation. You might just need a colder plug than stock. There aren't really that many causes of insulator cracking other than poor installation, detonation, or overheating. I don't think its poor installation if it takes you 8-10k miles to realize there's a problem.

Are you using a spark plug socket (not always a good thing) and are you torquing to spec, and are you using antisieze, and are you adjusting torque spec if you're using antisieze?
 
Caver Dave said:
That's like a squint one eye (tight), right? Versus a grunt & squint both eyes (very tight)?

Seriously though, I fail to see how that might cause the cracked insulators... :flipoff2:
Click to expand...

Mostly from over tightening, because proper torque is usually pretty light. Some spark plug sockets are capable of compressing the rubber sleeve inside the socket and cracking the insulator too. Those are just installation factors though.
 
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