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-   -   SBF Cyl Head Oil Return (http://www.clubcobra.com/forums/small-block-talk/145481-sbf-cyl-head-oil-return.html)

Sledge 12-18-2021 09:10 AM
SBF Cyl Head Oil Return
 
I understand that oil gets to the valve springs, rocker arms, etc. via the pushrods. How does this oil get drained back into the valley or crankcase? That oil has got to go somewhere.

It appears that there are drain holes, one at each end, near the valve springs, but then I am told there is no oil path through the cylinder heads. I'm chasing a leak and even with dye I haven't found the source yet. It isn't the valve covers or the china walls, there is no oil leaking above the exhaust ports.

Dart block, AFR heads.

bobcowan 12-20-2021 09:24 AM
The oil drains back through those holes at the end, and there is an oil passage there in the block. It also drains back through the push rod holes.

https://i.imgur.com/cuZ6Rx8.jpg

https://i.imgur.com/jbcc9Pj.jpg


Take the car to a shop that has a smoke machine. Where the smoke leaks out is where the oil is leaking from.

Gaz64 12-20-2021 04:15 PM
If the lower drains were not functional, the heads would fill up until the pushrod holes became the main drain holes.

How much oil in the valve spring area when you remove a valve cover?

Sledge 12-21-2021 08:51 AM
Thank you Bob and Gary. Bob, you confirmed what I suspected but could find no diagram or written reference on the 'net. Good idea in re using smoke to pinpoint the leaks. Gary, when I remove the valve covers there is only a very little oil between the springs and the head's valve cover gasket lip.

Thank you guys for responding, and Bob, those pictures are perfect.

blykins 12-22-2021 04:55 AM
Quote:
Originally Posted by Sledge (Post 1501022)
I understand that oil gets to the valve springs, rocker arms, etc. via the pushrods. How does this oil get drained back into the valley or crankcase? That oil has got to go somewhere.

It appears that there are drain holes, one at each end, near the valve springs, but then I am told there is no oil path through the cylinder heads. I'm chasing a leak and even with dye I haven't found the source yet. It isn't the valve covers or the china walls, there is no oil leaking above the exhaust ports.

Dart block, AFR heads.
Depending on the head gasket used, some guys forget that the head gasket doesn't come up all the way to the china wall and it leaves a gap. On some head gaskets, you have to put a dab of silicone under the head before you bolt the head on. That's an easy place for leaks to generate.


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