bigdsz

iTrader: (1)

I'm doing a 408 and the machinist told me my combustion chambers were 69cc, so I told him to mill the heads .022", to bring me down to 66cc, which I figured was around 11/1 CR. Well it turns out after I cc'd them myself that the machinist fk'd up, and now after milling they are only 63cc. This puts me at about 11.4/1 SCR and 8.9/1 DCR according to one of the calculators I used. Am I screwed with the CR's I now have to deal with, are they too high for a "safe" engine? Thanks.

03 BUSA

iTrader: (25)

For a NA motor you will be fine with a good tune. I have heard of guys with 11:8.1 scr on pump gas with no problems.

slow trap

iTrader: (22)

that is a touch on the high side but it is possible to run that high of a dcr on 93,i had 9.0 dcr on stock cubes.what cam are you going to run ? your dcr seems pretty high for 11:4 scr unless it is a pretty small cam on a tight lsa.

bigdsz

iTrader: (1)

I've got a Comp XER 244/248 .612/.615 112+2 with a 52* ABDC. I've got -8cc Weiscos going in, Erik@HorsepowerEngineering.com is doing the build, I hope we can go to a -10cc piston to resolve this issue.. It is beyond me how the machinist could make a 3cc error. These heads were not my first choice to begin with, but I need to keep them because of $.

Ferocity02

iTrader: (60)

If your running 93 octane or above you will be perfectly fine. You can always go with thicker head gaskets if you want to lower the compression.

bigdsz

iTrader: (1)

When I used the CR calculator I used .056 for gasket thickness. I'm using the OEM MLS gaskets, I really don't know the compressed thickness, I've heard .054 to .060. Uncompressed, I miked them out at like .065. If anyone has a better number I'll use it. I was hoping to use a .045 Cometic for abetter quench but that obviously won't work now.