Compression ratio
Can I ask why it's different than the factory rating? I thought the aluminum heads were a step up.
Don't get me wrong, it's not that I don't believe this. I just want to know why I didn't get the power I wanted.
I wish I could contact this guy. He and his father were very experienced in engine building, but mostly Chebby engines. This guy was a good friend, and almost begged me to let his dad do the build.
Because very few engines came from the factory with the advertised CR. Why you say???
Because you are buying a mass produced piece with tolerances for each and every part.
Sooooo, that means if you got damn lucky, you got an engine with the shortest decks, the longest rods, the tallest compression height and the heads with the smallest chambers, you'd be close to advertised.
As an example, you only machine the decks on a new block until the cleans up, and it that is .040-060 taller than what is called for, they run it. For the heads, it's the same thing. The new castings are only milled until the decks are clean and flat. So you could have a head that came off the mill with 74 cc chambers or 68 cc chambers.
Oh, I forgot to mention that crank stroke lengths vary. The nominal stroke is 3.313 but (going from memory here) I think the tolerance was plus or minus .010 stroke length.
So, if you are unlucky like me (unlucky in love too but my wife says otherwise) you'd get the tallest block, the shortest rods, the shortest stroke and the biggest chambers and the you'd have about 9:1-9.5:1.
That's how that happens.
Now I'm going to catch hell here, but that's why I NEVER deck a block to a number. Ever. You can screw yourself right quick.
And then you get a visit from the Wild Turkey to make you feel better!!
