The Stovebolt Site Forums The Shop Area Engine Shop Oil Passage to head

Hey all, I'm in the process of tearing down my 235 so I can prep the block to accept later, non-dowel bearings. On the way I've been cleaning things, checking oil passages, etc... When I got to the passage from the tube in the side cover that feeds the rocker arms I was confused. So, as I see it here's how oil gets to the tube that feeds the rockers. Let me know if somethings wrong.

1. Oil flows from the rear cam bearing to the tube in the side cover
2. Oil then enters the fitting in the block that feeds oil vertically toward the head
3. From the fitting, the passageway feeds oil into a small,very flat, opening in the head gasket
4. The oil flows through the VERY narrow space in the head gasket to the adjacent head bolt cavity
5. Oil then flows vertically through the head bolt cavity to a passageway in the head that leads to the tube that feeds the rocker shafts

So do I have that correct? Seems like the passage through the head gasket is quite limiting. Just wondering if that led to my rockers and shafts getting torn up. Thanks!!

I just realized I put this in the wrong place

Moved your post here to the Engine shop.

You have it essentially correct. Some 235's use a drilled (hollow) head bolt to get oil up into the head, which bypasses the gap in the head gasket. That hole in the head bolt is only 1/16" diameter, so is probably about as restrictive as the head gasket gap. I don't recall how the oil distributor for the rocker shaft is fed, but I think thru a threaded port in the head that is on the receiving end of the drilled head bolt.

HERE's the blurb from the 55.2 Truck Service Manual about rocker oiling.

My engine has the oil line from the block to the head under the side cover ,I think it is a 1957 casted block with a 848 head. The rockers are also different oil grove in center or offset and other differences ,you have to do a little googling the link Kevin gave you above is a good start .

Here's another link to the '59 Truck Shop Manual Supplement showing differences between oiling to the head between 1958 and 1969 235's. The separate oil line under the pushrod cover has been eliminated and replaced by a passage in the block itself coming from the lifter oiling gallery that lines up with the center head bolt.

Lots of imfo on pre68 Dave’s site.

And HERE is some information from Tim Lederman's site.

And HERE is a link to pre'68dave's site that Kevinski took a snapshot of.

Kevin, I think Oswald's head might be close to exploding now, with all the stuff we've posted.

The rocker arms only need a small volume of oil to lubricate them, but it MUST be there. The restrictors are there to prevent robbing the lower end of the engine of the necessary oil flow- - - - -if necessary, sacrificing the rockers to assure enough lubrication to the bottom end. That's a throwback to the "oil distributor" on the old spray-oiler engines, 216, early 235, etc. that restricted oil flow to the head until there was at least 15 PSI at the main bearings and oil spray tubes in the oil pan. From 1953 with the first full pressure 235s to the last of the series in 1963, there were several variations of the rocker lubricating system.
Jerry

The thing to remember is the rocker arm assembly is dictated by the engine block, not the cylinder head.

Ok, guess that's how it works. All the passages are clear, the oil flow through the opening in the gasket then up through the bolt cavity struck me as odd. I guess I'll just make sure oil is getting up top to all the rockers once it's back together. Thanks!

The drilled center head bolt was only used when certain block and cylinder head mismatched years of production was used together. As long as there's at least a seep of oil coming from the holes in the top of the rocker arms at idle speed, the rockers will be lubed sufficiently. At cruise speed, the flow will be considerably higher.
Jerry