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 Post subject: Has a head been milled?
PostPosted: Fri Nov 02, 2001 8:32 am 
Is there a landmark on the cylinder head to determine if the head has been milled? I'm guessing that perhaps a spec exists for the head-surface-to-rocker-arm-stand-saddle but don't have any drawings. What is the standard angle between the head surface and manifold surface? If the head surface is angle-milled, does the manifold surface also have to be changed? Also, I'd appreciate the website or phone number for Cox Brothers Performance. Thanks.

Ken_Sharp@bramco.com


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PostPosted: Wed Nov 07, 2001 10:01 pm 
Quote:
: Is there a landmark on the cylinder head to
: determine if the head has been milled? I'm
: guessing that perhaps a spec exists for the
: head-surface-to-rocker-arm-stand-saddle but
: don't have any drawings. What is the
: standard angle between the head surface and
: manifold surface? If the head surface is
: angle-milled, does the manifold surface also
: have to be changed? Also, I'd appreciate the
: website or phone number for Cox Brothers
: Performance. Thanks.


Finding a "landmark" as a head milling referance measurement is harder then it looks. I have been measuring different heads and reviewing blueprints I have and see that there are many differences year to year, this makes it hard to give one "simple answer".
The most consistant referance point I found was the head gasket surface to valvecover gasket mounting surface, this is called-out by most of the factory drawings as 3.6 inches "Ref." but on most the stock heads I measured, this was running in the 3.610 to 3.615 range.

The angle of the manifold surface to the block surface is easy, it's 30º and most racers do not adjust it if the head is "angle milled". (just "shim" the entire engine around if there is a problem with hood clearence or something)

I would not go by physical head measurments as much as I would rely on the actual "CCs" in the head's combustion chambers themselfs, this is called-out at 54 CCs for all SL6 heads but it also varies quite a bit. (usually in the 55 to 60 CC range) Valve type and seat depth have a major influance on the CC's in the chamber. Bottomline, is that it is best to CC the head , do the math and adjust from there.
Here is the Cox Bros. number:(614)268-9920 and a look at the factory head lay-out. (one piece of 4 pages) Have Fun!
DD

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PostPosted: Thu Nov 08, 2001 3:20 pm 
Quote:
: Finding a "landmark" as a head
: milling referance measurement is harder then
: it looks. I have been measuring different
: heads and reviewing blueprints I have and
: see that there are many differences year to
: year, this makes it hard to give one
: "simple answer".
: The most consistant referance point I found was
: the head gasket surface to valvecover gasket
: mounting surface, this is called-out by most
: of the factory drawings as 3.6 inches
: "Ref." but on most the stock heads
: I measured, this was running in the 3.610 to
: 3.615 range.
:
: The angle of the manifold surface to the block
: surface is easy, it's 30º and most racers do
: not adjust it if the head is "angle
: milled". (just "shim" the
: entire engine around if there is a problem
: with hood clearence or something)
:
: I would not go by physical head measurments as
: much as I would rely on the actual
: "CCs" in the head's combustion
: chambers themselfs, this is called-out at 54
: CCs for all SL6 heads but it also varies
: quite a bit. (usually in the 55 to 60 CC
: range) Valve type and seat depth have a
: major influance on the CC's in the chamber.
: Bottomline, is that it is best to CC the
: head , do the math and adjust from there.
: Here is the Cox Bros. number:(614)268-9920 and
: a look at the factory head lay-out. (one
: piece of 4 pages) Have Fun!
: DD

As usual, your response is well-studied and full of helpful info. Thanks for your time!

ksharp@iglou.com


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