I'm going to be putting ported 416 casting heads on my '86 LG4...

I ordered a set of gaskets and it comes with 2 head gaskets, teflon coated, not sure of the thickness. Should I use these, buy different composites, or buy shim gaskets? How much could these hurt my compression ratio, assuming they are 0.039" or so thick?

They're from summit and come with their "complete gasket set" for 30 bucks. If anyone knows the dimensions of these gaskets, let me know, because it isn't listed on summit's page.

Thanks

 

Well you need to get the right gaskets for the quench height not compression ratio. What are the motor specs? Not sure what gaskets your talking about.

 

motor is a stock 86 LG4 3.735" bore V8 with stock heads, I need to know if i should use a thin shim gasket or a composite and how much either will affect my CR which should be a 9.5:1 stock...

 

That motor came stock with a composite .040" gasket. This is what I would use to replace them and will retain your 9.5:1 stock comp ratio. Your Gasket is based on the quench height which should be with .030" to .045". I'll have to look for what the deck height is on those motors. Not sure right off the top of my head. I wouldn't use the steel shim unless It is necessary (only .015" thick). Using these just to boost compression is not the route to go. The quench height is much more important than the compression ratio. I can not stress this enough.