To mill or not to mill

[64.5 TX Stang]

Alright I bought a 69 "m" head that has been modified for a direct mount 2bbl. I CC'd the chambers and they are 60 cc, which to me indicates a 0.10 cut to true the surface during a rebuild. Now going onto an assumed stock 65 200 I would have a low compression ratio (i'm guessing around 8.2:1) IF I didn't mill the head. Now here's the rub, I am thinking about adding a turbo one of these days, probably in the next couple of years type of future and the low CR wouldn't be a bad thing, but in the mean time how will this low of a CR affect my perfromance as a N/A engine?

 

[69Falcon]

At 8.2:1 performance would definitely be down. In my opinion, you could mill the head to get 9.0:1 and still be able to turbo it without any detrimental effects.

 

[XFlow_Fairlane]

depends on how far you are wanting to turbo it in the future....just a mild setup for some extra umph or all out power. A higher static CR will give more low end torque to a motor. Some 2.3L guys like a 9:1 on a street driven car that isn't going for max power as it gives decent low end grunt (talking only a couple HP though really) but a low enough CR to run some decent boost on. even at 8psi a 200 really wakes up with boost (which would be a good streetable boost level for 9:1 CR) if you are having the head milled I would polish up the chambers at this point so if youdo boost it will help with any detonation issues. You can also build for 9:1 using the thinnest gasket you can find then switch to a thicker gasket when/if you turbo.

 

[64.5 TX Stang]

Both good suggestions. I think I will mill it to about an 8.8-9.0 CR. So now how much does it cost to have a head milled?

 

[XFlow_Fairlane]

I think I paid $20 extra while having a head rebuilt to get mine milled. if the head is being rebuilt then it shouldn't be too much extra (I would at least have it decked flat)