Spark Plug Gap... head or block?

[nittanylion45]

Hi,

I have GT40P heads on a 71 302 block for my 65 conv.

Should I gap the plugs witht he head spec (2000 Exporer, 0.054") or standard 302 gap (.038")? I would think the head spec would be correct. But, I would like a confirmation.

Regards, Jim.

 

[65fastbackresto]

The head

Contains the combustion chamber, would be the head speck I assume....

 

[86bluecobra]

Now from what I can determine and I maybe way off the efi stuff always has a larger gap then the carb guys. I'm not really sure why this is. I would start with a .044 gap and see what it is like. That being said the .038 I'm sure would work just fine.

 

[BlackGMC]

are you running a MSD box?

 

[nittanylion45]

Nope.

Just a pertronix coil and solid state ignition.

 

[CraigMBA]

Do the smaller .038.

The heads don't require a certain gap, per say. The gap is determined by the ignition system.

Bigger ignition = more gap.

 

[j69302]

heads are only concerned with spark plug reach. make sure you have the correct reach for your heads. reach is the threaded portion of the plug. too long and it could hit a piston or valve. too short and the plug wont be in the combustion chamber.

adjust the gap based on your ignition setup.