Author Topic: Jay, ? re: head drain holes.  (Read 1714 times)

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RJP

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Jay, ? re: head drain holes.
« on: March 06, 2013, 07:17:01 PM »
Jay, have you ever run into problems with cyl. head drain holes and head bolt interference due to the headbolt blocking the drain? Perhaps a careless drilling of the drain holes that were not offset enough? If so what was your solution to the problem?

jayb

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Re: Jay, ? re: head drain holes.
« Reply #1 on: March 06, 2013, 09:48:29 PM »
I've actually had head bolts blocking the oil feed holes down by the transfer slot in the head, so that oil won't get to the rockershafts, but have never seen a head bolt completely blocking a drain hole.  However, usually I will open up those drain holes a little where the head bolt goes by, to let the oil drain back a little easier.  There isn't a lot of room there in some cases.  If I recall correctly the early Edelbrock heads had some issues with this, and later heads opened up the size of the drain hole somewhat.  Can't remember for sure.  In any case I have gone in there with a die grinder and a burr and just made the passage around the head bolt a little bigger.
Jay Brown
- 1969 Mach 1, Drag Week 2005 Winner NA/BB, 511" FE (10.60s @ 129); Drag Week 2007 Runner-Up PA/BB, 490" Supercharged FE (9.35 @ 151)
- 1964 Ford Galaxie, Drag Week 2009 Winner Modified NA (9.50s @ 143), 585" SOHC
- 1969 Shelby Clone, Drag Week 2015 Winner Modified NA (Average 8.98 @ 149), 585" SOHC

   

RJP

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Re: Jay, ? re: head drain holes.
« Reply #2 on: March 07, 2013, 01:13:50 PM »
Thanks Jay, I've been fighting a drain back problem on a pair of D2 heads and after looking at several sets of iron heads of various casting numbers from C1s to the D2s there seems to be some variance in drain hole location in relation to the headbolt. Thanks again, Bob