I'm in the process of replacing the head gaskets on my L98. I figured I would replace the spark plugs while I've got everything apart. I have trick flow aluminum heads, btw. The plugs currently in use are Autolite 104. Just out of curiosity, I looked up what plugs are supposed to be in this engine and those plugs aren't even close. They have a .708 reach where stock is .460. Considering all of the things I've found screwed up on this car, I guess I shouldn't be surprised if these are the wrong plugs. What plugs do you guys recommend?

Steve

 

Those might not exactly be ""wrong". If the .708 reach isnt interfering with anything, that can be a plus. As long as they are the right heat range, (I say) you can roll with it.

http://aftermarket.federalmogul.com/...ce%20Chart.pdf

 

Aftermarket heads usually take different plugs than stock heads, especially aftermarket aluminum heads. You probably have the right plugs in there already. Thread reach is NOT something you want to get wrong in selecting plugs.

Call TrickFlow and ask them what plugs are recommended with those heads..... and use them.

 

I saw a stock 4.3 had too long thread reach. The valve got so hot the spring tension tried to pull the valve out of the combustion chamber...was ugly