Does anyone know what is the most that can be milled off a set of 68 455 big valve C heads?
I'm hoping to be able to bring it down to 70cc currently 85cc.

thanks,

 

I believe .005" per cc. 15 cc X .005" = .075" material removal.

 

If you have your heads milled that much , make sure the machinist mills the proper amount off the intake ports .
Otherwise your intake manifold isn't going to fit .

 

great thanks guys!
just curious whats the most you have ever heard of being safely milled off olds heads?

 

 

Couple of quick questions here please,
Were you using the stock hydraulic flat lifters in that engine?
Did you have to buy shortened push rods with that much milled off the heads? or did the stock length ones cope ok?

How much needs to be milled off the intake if you mill .012" - .015" off the heads? is there a formula to work this out?
Do you mill the intake side of the heads or the intake manifold flange?

I'm going to do just as the OP has suggested, so I'm keen for any info, thanks.

 

Go to www.wallaceracing.com Lots of calculaters

 

If i remember correctly, milling .006" off yields approx 1 cc reduction in volume.