milled question?
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On The Tree
Joined: Jun 2005
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milled question? I am planning on running a C2 cam."224/224-581/581 114lsa" and a set of afr 205 heads and I would like to know if I need to have the heads milled 30 over or not. Also please inform me on what the 30 over means, dont know what that means? Hope you guys can help me with that question and give me a clue on what kind of numbers I might put down. C2 cam, AFR 205 heads, fast 78 mm intake, ported throttle body on a stock 346, Hooker long tube 3 inch exahaust"full 3 inch." 
I am inclined to say yes as I have seen it done on several cars including mine for a time. Your best bet will be to clay the heads to find out. Basically, take it to a machine shop to make certain.
30 over means .030 inches-30 thousanths of material have been taken off of the base of the heads in order to shrink the size of the compression chamber. As the compression chamber is shrank, the compression ration is increased making more power.
With that setup, I don't see a reason that you couldn't see 400 rwhp through an M6. Less with an auto.
30 over means .030 inches-30 thousanths of material have been taken off of the base of the heads in order to shrink the size of the compression chamber. As the compression chamber is shrank, the compression ration is increased making more power.
With that setup, I don't see a reason that you couldn't see 400 rwhp through an M6. Less with an auto.
You only need the heads milled if you want to bump up compression. Higher compression means a little more power. The AFR 205s come out of the box 66cc which means your compression ratio (CR) will remain about the same as stock.
The first thing I would recommend is determining what final CR you want. This determines how much to mill. Also for the AFRs, milling .006 drops 1cc. So for example, if you want to achieve a final CR of approximately 11:1 then you will need to mill about .024 to achieve a chamber size of 62cc.
Hope this helps.
Brian
The first thing I would recommend is determining what final CR you want. This determines how much to mill. Also for the AFRs, milling .006 drops 1cc. So for example, if you want to achieve a final CR of approximately 11:1 then you will need to mill about .024 to achieve a chamber size of 62cc.
Hope this helps.
Brian
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
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From: BFE
Agreed, however please choose gasket before you decide on milling for desired SCR.
If you get a .040 gasket, you'll have to mill less.
Less mill is better in order not to affect flow too much, and thinner gasket will yield tighter quench.
If you get a .040 gasket, you'll have to mill less.
Less mill is better in order not to affect flow too much, and thinner gasket will yield tighter quench.
