I searched and found a good discussion on spark plugs back in 2009. But I wanted to clarify and double check one point: I know that the S after AC 45 indicates an extended electrode plug; in the previous discussion cited above, people talked about using them in later Chevy engines, and also talked about problems using them with domed pistons.

My question is this: Can I use the AC 45S in a stock 1938 216 without problem? I believe they should be fine, but want to make sure.

Thanks,

Jim