The Jockey Journal Board - View Single Post - Pre-Unit Case "use or not"

Tony the torch · 12-31-2011, 08:45 PM

the reason the pre unit rocker boxes won't work is apparent in the last picture here..look down the head bolt hole and you'll see the head bolts were moved further out in an effort to cure the cracking that is common in pre unit heads and thus the head bolts won't go through the rocker boxes into the spread out head bolts of a 9 bolt head. it's really apparent when you compare the 8 and 9 bolt head gaskets.
there is easy a way to fix the pre unit head... if you order 4 of the head bolt sleeves from the head bolt holes next to the intake valves on a later 66-7? unit head, (they used these steel sleeves because the intake ports often went through into the head bolt holes), so then you drill out the pre unit head bolt holes and press in the sleeves it stops the air leaks form the cracks and you can keep on running the 8 bolt pre unit head even with the cracks in there.

12-31-2011, 08:45 PM	#13
Tony the torch Senior Member Join Date: Oct 2008 Location: still in so cal. Posts: 3,691	Re: Pre-Unit Case "use or not" the reason the pre unit rocker boxes won't work is apparent in the last picture here..look down the head bolt hole and you'll see the head bolts were moved further out in an effort to cure the cracking that is common in pre unit heads and thus the head bolts won't go through the rocker boxes into the spread out head bolts of a 9 bolt head. it's really apparent when you compare the 8 and 9 bolt head gaskets. there is easy a way to fix the pre unit head... if you order 4 of the head bolt sleeves from the head bolt holes next to the intake valves on a later 66-7? unit head, (they used these steel sleeves because the intake ports often went through into the head bolt holes), so then you drill out the pre unit head bolt holes and press in the sleeves it stops the air leaks form the cracks and you can keep on running the 8 bolt pre unit head even with the cracks in there. __________________ Possibly the finest private collection of Whitworth screwdrivers in the U.S. Last edited by Tony the torch; 12-31-2011 at 08:58 PM.