What is the purpose of angle milling a set of heads?

I would like to get some info on the process and why they do it.


Thanks


Travis

Ive done it to increase compression ratio without changing pistons. It makes the combustion chamber smaller. You also have to angle mill the intake surface so the geometry to the intake stays the same. Valve clearance to piston has to be rechecked. Valve geometry needs to be checked too and maybe pushrod length changed depending on how far you go. If going into the bottom end anyway, just change pistons.

if you strait mill them, the area were the intake manifold seats gets smaller and smaller to the point were it hits the heads long before it seats on the block and have to mill a bunch of the intake to fit the heads. Angle milling makes it so it is not as drastic on the intake because the intake side of the head gets very little milling wile the exhaust side gets alot. Charlie

I thought it had to do with flame travel within the combustion chamber. If you angle mill, you don't reduce the tight quench area as much as if you were to flat mill. You are also angling up the intake runners to a more desirable angle with the intake. I know that it works, I am just not sure why...

Ask Mr.Gadgets----he had his heads angle milled, but I don't think he'll ever do it again. He had a real bad go-a-round with them.

Yeah.. ask Gadgets.. he did it.. LOL

The big advantage seems to be the angle of the intake valve and flow into the combustion chamber. I did angle mill a set of heads and made some serious power with a 513" motor. 670ft/lb @ 5000; and 690hp at 6000. I was running around 9:1 compression and the motor would buzz to 6300.

But there are a lot of things to consider, as has been mentioned in this thread. Intake manifold spacers, valve train geometry, etc. Problem is when a head breaks and you cant find someone to fix it, then you have to match the old one or buy new ones.. Then maybe your intake manifold is useless! Well the gains received from angle milling are negated by the new heads that already change valve angle and have CNC porting.
I would not do it again! I had to replace a head and it cost me a year of boating. So do your home work and make your decisions.. but take it from one that has been that route.. It is too much trouble for the gains you might receive. Save your money and buy a set of CNC'd heads. You can replace them in week when one fails.. Just my .02

Actual cost of replacement = $3k+

Time out of the water = 1 year!

Respect for off the shelf products...... Priceless!!

Was is this?----a commercial??? LOL! You crack me up Gadgets!

Thats what i needed to know guys. Thank you.. it doesn't sound like i want to go that route.. So far I am going with a set of 190cc AFR heads straight milled to 64cc from 74cc. And they are cnc ported. This is the best head I could find that would flow this good. I got a few emails from dave at AFR, set would be $1250 ready to go. Milling is $150 and price for " no parts option" was $1135. So he is telling me there valves, springs, retainers, locks, seals and shims are only worth $115, that seems like pretty cheap parts to me..




Travis

Traviss, I don't think you can go wrong with CNC ported heads, especially the AFR's. You want to go with a company that has the best advanced technology for research, and abunant resources.

Buy a bunch of beer and go for boat rides on other people's boats. Takes all the worry out af all that broken-boat stuff.