milled heads
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,010
Likes: 1
From: Sweden/Stockholm
milled heads
If you whant to make a 72cc head make the same comp as 64cc heads, and you dont whant to change the pistons you must mill the heads, right?
And does that mean you also have to mill the intake, and get custom length pushrods?
And does that mean you also have to mill the intake, and get custom length pushrods?
Le Mans Master
Joined: Apr 2005
Posts: 6,363
Likes: 429
From: Seattle Area WA
You will need to "angle mill" the heads to remove material and then you will need to remove a corresponding amount of material from the intake to match the heads. Engine building books will have the formula for how much to remove. I do not know if it is possible to remove that much material from a 76cc head though.
Drifting
Joined: Jun 2005
Posts: 1,824
Likes: 1
From: Middleboro Massachusetts
I believe the amount of material to remove on the angle milling is .017" per inch of head width starting from the exhaust side. This rolls the valves over more to the center of the bore and makes the combustion chamber smaller at the same time. Very trick 
Advanced
Joined: Aug 2006
Posts: 65
Likes: 0
Had some Dart Iron Eagles straight milled. Took off .030", which, according to Dart, reduced chamber volume from 72cc to 67.5cc. With our combo, it increased CR from ~8.8 to ~9.2.
Dart recommends .060" max straight mill. Your heads may be different, depending on deck thickness.
We didn't have to do anything to the block or intake manifold.
Dart recommends .060" max straight mill. Your heads may be different, depending on deck thickness.
We didn't have to do anything to the block or intake manifold.
Last edited by Mike_B; Aug 21, 2006 at 09:56 AM.
