LXguy
Well-Known Member
OK:
I've been trying to perform a 360/5.9 upgrade to my 71 Dart to try to make Pinks All Out in Indy next month. It hasnt been going well.
Being faced with some garage time and no opportunity to proceed with my project, I decided to compare the figures in one of my Mopar hot-rodding books with what my 318 actually is. I measured the depth that the piston sits down in the bore at TDC and cc'd the stock cylinder heads. It was very difficult because even though this engine only has 31K miles, it seems like all the exhaust valves leak a little bit. My measurements aren't going to be laser accurate, but they're pretty darn close to reality.
Anyways. The book says the heads are 60cc. Truth: 68cc
Book says the piston will be in the hole .050 Truth: .094
Combined with a stock gasket thickness of .038, this makes my stock compression ratio........
7.87:1
Sheesh. I'm surprised the thing even runs!
It would probably make more power if I could find some 80 octane gas someplace. LOL!
Needless to say putting any kind of cam on that combination would probably lower the dynamic compression to some ridiculous level that would make it a pointless exercise..
Lot of people talk about building stock shortblock 318 combos. Just wanted to let you know what you're up against.
Steve
I've been trying to perform a 360/5.9 upgrade to my 71 Dart to try to make Pinks All Out in Indy next month. It hasnt been going well.
Being faced with some garage time and no opportunity to proceed with my project, I decided to compare the figures in one of my Mopar hot-rodding books with what my 318 actually is. I measured the depth that the piston sits down in the bore at TDC and cc'd the stock cylinder heads. It was very difficult because even though this engine only has 31K miles, it seems like all the exhaust valves leak a little bit. My measurements aren't going to be laser accurate, but they're pretty darn close to reality.
Anyways. The book says the heads are 60cc. Truth: 68cc
Book says the piston will be in the hole .050 Truth: .094
Combined with a stock gasket thickness of .038, this makes my stock compression ratio........
7.87:1
Sheesh. I'm surprised the thing even runs!
It would probably make more power if I could find some 80 octane gas someplace. LOL!
Needless to say putting any kind of cam on that combination would probably lower the dynamic compression to some ridiculous level that would make it a pointless exercise..
Lot of people talk about building stock shortblock 318 combos. Just wanted to let you know what you're up against.
Steve