[DeTomaso] Venting crankcase to valve cover (was Oil pan gasketrecommendation?)

[Doug Braun]

Jack,

    Thanks for adding a very important point.  I used this "drill to clear"
technique on the oil drain back holes on two pairs of heads.  One was a set
of '73 open chamber and the other was a pair of '70 closed chamber.  For all
4 heads, on the doglegged holes, I was very careful to only drill to the
point where I just started to hit metal.  As you say, one should be very
careful not to remove any of the casting, only the grunge.

Doug Braun
blue 73L #5505
  -----Original Message-----
  From: JDeRyke at aol.com [mailto:JDeRyke at aol.com]
  Sent: Monday, October 06, 2008 11:15 AM
  To: doug at silicondesigns.com; detomaso at realbig.com
  Subject: Re: [DeTomaso] Venting crankcase to valve cover (was Oil pan
gasketrecommendation?)


  In a message dated 10/6/08 9:52:05 AM, doug at silicondesigns.com writes:


    One of the head's drain back holes is straight while the other (as Jack
so often cites) is doglegged.  But it's only a single dogleg which can be
easily drilled from both ends, meeting at the angle in the middle, to
completely clean out this passage.....


  Be careful to perfectly match the existing angles if you get 'aggressive'
in drilling out the dog-legged passages. Stock Cleveland head castings are
full of shifted cores just like the blocks, and on the head I cut up, the
factory drilled passages did not match the casting cores very well (see
photos POCA newsletter April 03). In the article, I mentioned that
oversizing either drainback passage very much is risking scrapping a head if
you do it wrong & hit water. FWIW- J DeRyke