73C34me

Greetings, I am considering having my heads milled this winter for more compression, as I am running race gas anyway. Does anyone now the impact of airflow through the ports if the chamber is made smaller? Is there a benefit to airflow, detonation control if the heads are angle milled? Thanx in advance.

Combo: 11:1 385 sbc. 6" rods, forged flattops, 64cc ported edelbrock rpms with 2.05" intake, 825 mighty demon on a edebrock vtr. jr. with a brodix turtle, all portmatched. Cam is a comp cam 294solid XE with 252 at .050 intake .565" lift at valve. ex. is 262@ .050 with .575" at valve. I am using 1.6 roller rockers. Cam duration maybe off a smidge, as i am utlizing my aging memory. Cranking compression is 200lbs. MSD ignition

fast idle

would it be better to get the block "0" decked to raise compression??

73C34me

thanks for pointing that out. the block is zero decked now

Yellow73SB

probally cant be that badfor air flow. im running 58cc heads and i milled mine down and in about a week ill tell u if they dont flow as good.yours will still have more hp becuase you ahve a bigger cam. my bottom end is pretty much the same. i have a victor intake not a victor jr.

zwede

Angle milling improves airflow because it reduces the valve angle. A few years ago Edelbrock offered their big block heads in 110 cc and 100 cc versions. The 100 cc were the same heads but angle milled and valve angle changed 2 degrees. Flow tests showed a slight improvement in the milled 100 cc version.

427Hotrod

Generally it's a std deal that it improves airflow...but....

The fact is most porters don't actually test them afterwards and do a real A-B test.

I can tell you a strange case on my Brodix heads. After they had spent A LOT of time on the flowbench producing optimal valvejob angles, back cuts and port shapes as well as lots of chamber work, the final thing to do was to angle mill them to get CC's back where they should be. The chambers had ended up pretty large.

After milling we checked them and found a very significant loss on this set of heads. It literally took another week of flowbench work to get them back where they were as well as pick up what they should have gained by milling.

So, I'd do whatever you have to to get CC's you need...but I'd flow them afterward to make sure. Do chamber work first, then mill, then develop ports. Head porter was surprised as anyone!


JIM

73C34me

Thanks guys, Also any experience with gasket sealing issues after angle milling?

427Hotrod

When you have them cut...MAKE SURE you find a machinist that knows how to cut the intake face of the HEADS too....do NOT cut the manifold! This way the heads will always fit ANY manifold. Otherwise the two are married forever.

If he does it right you will have zero issues. I've never had one leak, and I've had lots of milled heads.


JIM

tigers123

Be careful with the head milling. When I was a pup I got stung by this guy who sold me a set of milled heads. No intake would fit on the darn things, and it would leak water into the engine. I found out the hard way you can have a set of boat anchors instead of heads. Also any metal removed from the heads cannot be put back. Either buy the heads combustion chamber small enough or buy different pistons if block is zero decked. If your not sure when buying heads wether they are milled or not look for flycut marks on the surface of the heads, and sharp edges around combustion chamber. But most people don't bother to mill intake side to keep a proper relationship of fit for the intake manifold.

427Hotrod

You're right..they don't....that's why I said you need to find a GOOD machinist that knows about this stuff. If done correctly..it's no big deal. If done poorly..it's a PITA!!


JIM