Oil In Intake

[scrap151]

This has probably been discussed but I did a quick search and didnt find anything. Heres whats going on with my 41 knuck. My intake and intake side of the heads are soaked with oil after fresh top end. this is the third time I have had the top end apart for this reason. Oil gets in the cylinders, burns becomes carbon and wipes out the cross hatch and rings. This problem started after the bottom end was done and the wheels were replaced because I had 61" wheels and 74" cylinders. I'm assuming oil is not returning and its coming through the guides. I set the intakes at .002. I fitted the tins before assembly, cleaned out the return lines in the tins, lifters are the same as before build, replaced breather with S&S version. The tins have the small vent holes. So I'm looking for some direction, has anyone seen this and what did they find or what should I try? Thanks for any help!

[Rubone]

Scrap,
Knuckles return oil by vacuum created suction. It draws the oil up the tubes at the bases of the valve cups into the rocker boxes and down the pushrod tubes. The intake side only top tins have a vent hole in them to prevent airlock. So...You need perfect sealing of the tappet block and cam cover gaskets, good pushrod seals, a good seal on the rocker boxes, no cracks (common) in the lower tins, and the correct Knuckle breather gear with the extra hole to create the suction. If any one of those isn't righ, it will puke. It also is not capable of keeping up with a modern pump, so if it has a Panhead or Shovelhead pump it must have the oil supply restricted to the top end.
'61 wheels and 74 cylinders are not an issue, that was a common mix in the old days and has zero to do with oiling. They tend to be smoother runners than 74s, closer to square dimensions.

[scrap151]

Thanks Rubone,
I'm going to pull the cam cover tonight and start working my way back through the system from the breather. Check breather timing, I'm sure it was right but now I'm second guessing myself. Check the gear for the hole you mentioned, passages are clear, cam cover gasket and surface, lifter block gaskets, pushrod seals and see what I find. I cleaned the return tubes in the tins when I had it apart and there were no cracks in the rocker boxes. Thanks again, I will post my findings.

[scrap151]

Ok, I resealed the cam cover, lifter blocks, checked the pushrod tubes and the breather gear and timing. I havent pulled the tanks yet to look at the tins but when I put The engine together I straightened the tins so they fit together nice before I assembled them. Here is something I also did and wonder if anyone has a spec on the vacuum I should have. I took an old upper pushrod tube, drilled a hole in it and brazed a short piece of 3/16" steel line to it so I could put a vacuum gauge on it. I'm only getting about 2 to 3 inches of vacuum running, idle or 2000 rpm. Any thoughts or a spec on this?
Ok, thanks!

[1950Panhead]

This should be enough to suck oil from the valve spring cups.
Your first post gives the impression oil is sucked from two cups and not sucked from two cups.
Remove the cup lines from the rocker box and blow through them, all four need to be clear.