Blowback our of the TBI

[Supercharged111]

Yeah mine (Summit Racing made by Trick Flow) use 3/4" depth with gasket instead of 5/8" tapered but, that wouldn't cause the OPs issue.

Yeah I agree, was just pointing out to Schurkey that there is a physical difference.

 

[Schurkey]

Yeah I agree, was just pointing out to Schurkey that there is a physical difference.

The point I was trying to make, was made much, much better by Buffalo90 from Oppositeland.

There's a physical-strength issue with aluminum heads relating to grip length of the threads. So, sure, aluminum heads and the spark plugs that fit them tend to have a longer threaded section than iron heads. But aside from the thread engagement and resulting shell-length difference, the construction of the plugs is EXACTLY THE SAME.

So the idea that "Iron head spark plugs" don't provide proper spark in aluminum cylinder heads is totally false. The problem is more about blowing those spark plugs through the hood, or breaking them off in the cylinder head--as AMPLY demonstrated by the brain-trust at Ford. For fukk sakes, those boneheads couldn't build an oil drain plug five decades ago, now they've chosen to entirely screw-up industry standards for spark plugs--and THEN they set the "recommended" service-life of the plugs so that the first plug change happens AFTER the warranty runs out. And so far as I know, the Federal Trade Commission allowed them to screw thousands of customers on this deal without penalty.