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Location:
Lost in the K hole
Registered:
May 2002
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 to drill or not to drill....
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Sat, 03 August 2002 12:43
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Topic: Counter-sinking (widening) the camshaft oil hole outlet
ive just been stripping a 7m head im rebuilding... checking tolerances etc... and ive noticed that the camshaft oil holes are a simple straight bore. on others cams ive looked at from high perofrmance engines etc, the oil holes are countersunk (widened) at their opening into the cam bearing journal. im thinking this widening of the oil hole outlet is a good idea, allowing the initial outflow of oil into the journal to give more coverage/ lubrication.
should i grab a countersink tool and open up the oil feed outlet holes a little??
one of my main reasons for thinking of doing this is that presently there is the odd significant score mark in the camshaft bearing surface due to oil contamination. these marks start from the oil hole outlet where the debris entered the journal initially, then they do about half a lap around the cam before dissappearing. im thinking that by widineing the oil outlet hole, i will let oil escape into the bearing journal beyond the location of the scores, helping lube the bearing a bit more?
to drill, or not to drill, that is the question.
cheers
ed
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Location:
Eskilstuna, Sweden
Registered:
May 2002
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 Re: to drill or not to drill....
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Sat, 03 August 2002 14:42
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DRILL!
I can't think of any significant side affects from a little countersinking, a littel funnel in effect for each journal.
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Toymods Board Member
I supported Toymods
Location:
Turramurra, Sydney.
Registered:
May 2002
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Re: to drill or not to drill....
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Sat, 03 August 2002 14:50
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In almost all engine rebuild articles I've read, they mention 'chamfering' these oil passages, and the pictures made me wonder if it meant creating the countersink shape (surely it would be done from factory, or so I thought) or just smoothing up & radiusing the edges. Now I know.
I would do it for sure, but wait for a second opinion before you do it! 
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I supported Toymods
Location:
I renounced punctuation
Registered:
May 2002
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Re: to drill or not to drill....
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Sun, 04 August 2002 01:07
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Ed, it's called chamfering and comes highly recommended. Did you get that book? It's all in there. 
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I supported Toymods
Location:
I renounced punctuation
Registered:
May 2002
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I supported Toymods
Location:
melbourne.victoria.austra...
Registered:
June 2002
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Re: to drill or not to drill....
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Sun, 04 August 2002 11:45
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doesnt a chamfer entail cleaning it out by actually drilling it? (scuse my ignorance  )
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Location:
Lost in the K hole
Registered:
May 2002
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Re: to drill or not to drill....
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Sun, 04 August 2002 12:32
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grega:
chamfer basically means to bevel the inner edge of the hole, making the opening wider such as cone:
from this:
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to this:
\ /
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bloody ascii... the V is obviously sposed to be wider than the bore of the hole.
cheers
ed
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I supported Toymods
Location:
melbourne.victoria.austra...
Registered:
June 2002
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Re: to drill or not to drill....
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Sun, 04 August 2002 22:05
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tis OK ed i get what you mean ta dude
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