KJL

What is the recommended spark plug gap for ACDelco 41-943 platinum plugs?

TorchRedlt4man

.050 inch.

RollaMo-LT4

LT4 F45

.050 inch and 18 to 22 lb-ft of tightening torque

AzMotorhead

Updating an old thread.
Spark plug gap was decreased from .050 to .040 because of random missfire codes.

mtwoolford

Thanks; this tidbit is going in my FSM

grandspt

Hi, was this a service bulletin? I have had my car for 21 years and always used the .050" gap.
Just wondering where this gap change came from.
Thanks

itismeTim

Hello guys,

i was changing the spark plugs and everything went wel till i hit cylinder 8.

Anybody seen this before? I ordered nee Delco’s cause there was no issue with then.



The tip is pressed down during installation. I used force but not excessive. Old plug goes in and out without this problem.

With the tip depressed they seem the same size. Gap is 0.50 on the bend one. Aligned on the point where it is seated in the head.

This is the new one i used, which got bend.

KJL

Check the overall length of the new pug (Un-bent) and compare against new. Next I would check to see where the piston is in the cylinder. Stick a plastic or wooden dowel in the spark plug hole and see if the piston is at TDC. DO NOT TURN TOUR ENGINE OVER UNTIL YOU FIGURE THIS OUT. I have a cheap bore scope from Harbor Freight that comes in handy for these types of situations. Also, check diameter of shoulder...they look the same however.

Also, the original plugs look to be good shape, why the change? The gaps seems a bit much. Read comments above in old thread. It seems gaps were reduced to 0.04". That seems like a more reasonable gap.

You also may want to start a new thread. This one is over 3 years old.