copper

Does anyone know why these Autolite 3923s are different? I bought 4 of these at 1 place and 2 at another place. I was going to install them today and realized they are not the same. One is slightly longer than the other, the metal is different and the end where the spark plug wire connects is...

I recently pulled my engine out and I am installing an HKS MHG. I took my head and block to a machine shop and both are straight and true. The only problem I have is the rear lower timing cover on the block is higher by .002 inches. Its flat for about an inch from the exhaust side but then all...