I'm rebuilding my 305 CFI motor and am having some doubts about the head gasket. Neither the block nor the heads have been machined, so everything is factory spec -- meaning the motor should have a 9.5:1 CR.

I bought a FelPro gasket kit from Summit which included a set of 8510PT head gaskets. However, I can't find any information about the compressed height of these things. I even emailed Summit tech support and they basically had no idea -- which is incredible. The FelPro/Federal Mogul site has no technical data -- which is also incredible.

As best I can tell from various searching tonight, the FelPro gaskets have a .041 compressed height, which seems like a lot. The non-compressed height is 0.050.

I found a veeeeeeery old post from 2004 here on TGO that says the GM gasket for my 305 is p/n 10105115 which has a .016 compressed height.

https://www.thirdgen.org/forums/tech...endations.html

The GM gasket is still available, so I'm curious if I should go get those or stick with the FelPro.

Based on calcs I've done, the GM gasket with a 0.016 compression would give me a 9.8:1 CR, which seems on the high side. OTOH, if the FelPro gasket truly has a 0.041 compressed thickness, that knocks the CR down to 9.3:1.

My goal is factory performance (if you can call 165 HP "performance" ) so the .5 CR difference between the gaskets probably means very little. I am also assuming my pistons are 0.025 in the hole since I haven't put the rotating assembly back in yet.

I know really need final measurements to make a proper decision, but since this is all stock I figure my assumptions are pretty safe.

I am curious to hear what opinions people have on the gaskets. Post up!