The thing about a 318 and compression is, it's a short stroke engine. They are more of a challenge to get compression and cylinder pressure from than a long stroke engine. With the reduced TDC dwell time, the shorter stroke doesn't have the time a long stroke engine does to build the same cylinder pressure. So the scope of parts and machine work to get good compression and cylinder pressure on short stroke engines is a bit more narrow. Even the famous 340 didn't have what its ratings said it did for compression. Not by a good bit. It's kinda like building an engine 2 cylinders down like a slant 6. You have to do things a little differently.
