Compression Ratio

[Charger Fan]

I haven’t done the calculation but I’m thinking someone has before me. I have a ‘73 440 engine that I want to build with a set of ‘67 440HP 915 heads. Going to keep the stock pistons and rods. Hoping to move the compression ratio to the mid 9’s and want to be less than 10. I don’t know how far in the hole the pistons are at max travel height and don’t know the thickness of the head gasket yet. Not looking for exact number but I’m assuming someone has a number I can use as a reference point.

 

[R/T Boy 67]

If you want 9.5 CR you will need new pistons. The actual CR of your stock engine would be 8 or less. The 915 heads might net you .5.

 

[1 Wild R/T]

73 440, stock piston will be somewhere in the .140-.160 in the hole... What I refer to as "might as well send out a search party"... Stock iron heads you can run a steel shim head gasket which typically measure around .021 compressed... 915 heads that haven't been milled come in around 81-84 cc

 

[496 polara]

Max effort would be to square deck the block and mill the heads some. With a steel shim gasket you might get close to 9.0-1.

That will be a power increase everywhere even with the stock Cam. A good valve job and a little porting go a long way.