I'm in the process of tearing down a 1969 396 350 horse motor. I believe it is a L34. Block casting number is 3955272T. The heads are the 1966 oval port heads that read 3872702. I believe these heads have a 98 cc chamber.

After removing the heads, I noticed the pistons have a 040 on the top. I assume the bloack has been bored to 40 over. The pistons have a large bump on them. Since this is my first build, I'm assuming this is a domed piston. The head gasket was blue. I have been told this is probably a Fel-pro gasket.

I don't believe the block has been decked, since at the right front of the block, on the small area that sticks out from under the head, you can still read the Engine Assembly Date and Suffix code. This would be directly below the alternator location on the passenger side of the car.

My question is what is the best guess as to the compression ratio of the engine. With a 98cc head and with a dome piston, I would guess probably 11 to 1 or 12 to 1. I was hoping it was something that was pump gas friendly. I guess I could swap out the heads or replace the pistons.

Can anyone give advice or help identify the compression ratio.