is it necessary to also mill the intake mating surfaces when zero decking the block? if so, how much in relation to the amount milled off the deck surface? for arguments sake lets say we are taking .020" off the deck...

 

you wouldn't need to mill the intake if you have the block zero decked, at least none i ever see or did.

 

The area of the great walls must be taken down, not the intake...you mill the intake if you mill the heads and you cant get the heads intake surface cut

 

.015-.020 is about as much as you would probably should go without adjusting the intake side of the head.

Always mill off of the head, never your intake, or the intake is only good with those heads and cant be used on other motors.

To calculate the proper amount to mill off the intake side of the head your take the amount you took off of the deck of the head and multiply it by 1.2. So to be exactly right if you take of .020 from the deck of the block or deck of the heads, you would need to take .024 off of the intake side of the head.

This is becasue sbc heads are 80 degrees, not 90 degrees, like some Olds heads. If it were 90 degree it would require a 1:1 ratio. The 80 degrees is what makes it a 1.2

 

exactly what i was looking for thanks