hey guys,i have a set of afr 195cc heads that have a 74cc chamber.right now my compression is too(9.3:1) low and i want to mill them down.my question is has anyone ever milled the down to say 68cc?any problems?if i have them milled to 68cc i would have a static of 10.3:1 with a .015 gasket.is that too much to mill them?of course i will have to check ptv clearance.any help would be appreciated.
mike

Mike,
AFR's web site might have the correct info, I know the instruction sheets that come with the heads do. Most small block heads take about .006" per cc so you are looking at cutting about .036" off them. Probably will have to cut the intake surface too.
Hope this helps,

Unless you have a lot of dollar$ in porting why not just trade them or sell them and get what you need. Consider the dollar$ to get them cut the amount you can discount them and you'll break even, at least in theory.

hey guys,i have a set of afr 195cc heads that have a 74cc chamber.right now my compression is too(9.3:1) low and i want to mill them down.my question is has anyone ever milled the down to say 68cc?any problems?if i have them milled to 68cc i would have a static of 10.3:1 with a .015 gasket.is that too much to mill them?of course i will have to check ptv clearance.any help would be appreciated.
mike

We just did a 383 for a customer and we milled the AFR heads to 68cc chambers and from there we correction cut the intake side of the heads and the intake fit perfect. And when we preped the block we cut the top of the block .100 as thats a silicon fit and everything fit fine.

thanks bill,
i realize that i would have to mill the intake too.i will have to check out afr's website.
mike

That's the one thing I never got about AFR -- the big combustion chambers. Really adds to the cost when you have to cut them down and correct the intake.

carl,
thanks for the input.those heads u milled i assume were the 74cc chamber correct?i am wanting to do this with the engine in the car so the block is not going to be touched.

eric,
i hear ya.i got these from afr cause someone else didn't want them so i just took the 74cc chambers.unfortunately due to a personal situation i had to put the motor together with the crank and pistons i already had.otherwise i would have bought a different bottom end to correct my compression.

one more thing, will the machinist know how much to take off the intake from how much he takes off the heads?or will i have to measure it myself?

That's the one thing I never got about AFR -- the big combustion chambers. Really adds to the cost when you have to cut them down and correct the intake.

Now I understand.

one more thing, will the machinist know how much to take off the intake from how much he takes off the heads?or will i have to measure it myself?

Click on this link and print this out for the machine shop doing the work and you may have to cut the bottom of the intake so it doesn't set on the block.

http://home.isoa.net/~mharrisj/mill.html

thanks alot carl!!that really helps out alot.
mike

Why would you have to cut the intake side if you flat mill the heads? That doesn't change any angles, nor does it move the intake faces of the heads at all. All it does is move the head intake bolt thresads down (and the ports too I guess)

I flat milled my Darts .040". All I had to do to make everything fit is elongate the bolt holes in the intake manifold a bit. (and yes, I know my intake port match is different, but then this isn't a max effort build.)

Why would you have to cut the intake side if you flat mill the heads? That doesn't change any angles, nor does it move the intake faces of the heads at all. All it does is move the head intake bolt thresads down (and the ports too I guess)

I flat milled my Darts .040". All I had to do to make everything fit is elongate the bolt holes in the intake manifold a bit. (and yes, I know my intake port match is different, but then this isn't a max effort build.)

Any time you flat mill heads you should correction cut the intake side of the heads or manifold as we corrction cut the intake side of the head as you buy any intake manifold take it out of the box and bolt it on. And when angle milling a set of heads all you do is bring the original angle back.

The heads being at a 45 degree angle and when cutting them it causes the the intakes to set higher and correction cutting puts it where its should be.

And in most cases if we are building the whole engine and we deck the block to 8.990 we add theat to the equation and everything fits fine.

Hope this helps

So.... cutting the intake side of the heads will lower the intake manifold so the ports and the bolt holes line up again, at the (relatively unimportant) expense of the end gaskets?

That is, the ports and bolts would line up, but there would be no place left to put the end gaskets (use a bead of silicone instead)?

yeah jim,i think thats what they are saying.i always use black rtv anyway.

I just used a die grinder and enlarged the boltholes in the manifold until I could get the bolts in. I wonder how bad the port match is right now (.040" flat cut & .015 shim gasket) how I could check it the next time it's apart? and how much it would really effect performance? (heads are iron eagle 180's, manifold is perf rpm)

Seems to be one of those areas where shade tree types like me can and did screw up. I imagine it would have only been a couple bucks extra to shave the sides while the shop had the heads.

I ordered AFR 195's with 64cc chambers. AFR cut the heads some .050 or so from the stock 74cc for the extra $150 mill fee and they did a good job on both sides,, Had no fitment issues going to RPM Airgap. I cc'd them when I got them, On the money. Running 10.1 pump premium.

hey thanks z..thats good to know.i am going to talk to my machinist this weekend and see what he has to say.