The Stovebolt Site Forums The Shop Area Engine Shop Cylinder #1 rockers hardly getting oil

My rockers above cylinder #1 are hardly getting oil. All the other rockers have the oil bleeding nicely from the oil holes in the tops But #1 just hardly dribbles out. I have removed the shaft and checked for debris and sludge. Also checked the the rocker hole and all is clean. Possible fix for this? My oil feed tube located in the center of the 2 shafts is also almost fully pinched off. Even if i rev and hold the rpms up it still hardly comes out. My oil psi reading is nice and high on the gauge sitting around 35psi.

Did you do any cleaning when you checked for debris and sludge? Run a wire down the supply holes? All of them?

The pinch in the line over the rocker shaft is to force the oil to the ends of the rocker arms; sludge build up could cause the #1 rocker arms to just dribble, or the rocker could be worn down enough to block off the oil supply.

That is a good oil pressure reading, but I'd be wary of trusting it alone if it's the original mechanical one- what year engine is this?

Brad

its a fully rebuilt 55 235. All the holes and passages are clean. I don't see any obstructions.

wolffcub,

Oil just dribbling out of the furthest rockers might not be anything to be alarmed about. You are getting flow.

Wait to hear from others who regularly work on these engines, like Pre '68 Dave.

There are a number if possibilities.
First, there could be to much clearance between the rockers and shaft due to wear. This would allow oil to leak out the sides of the rockers, preventing it from reaching the vent hole.
Since the engine sits at a downward angle #1 rocker is the highest and the first to starve if oil is bled off from it or the other rockers.

Second, since you said your overflow tube is pinched off we can assume you have a pre 1959 engine. Up to 1958 the groove inside each rocker is centered. If a 1959-62 rocker was used, which have the groove moved 1/4" offset, it will be hard for the oil to reach the vent hole.

Third. It is very common for the rocker oil restrictor orifice to become clogged. It has a 1/16" hole in it. It depends on the year as to where this restrictor is, up to 1957 it is the fitting at the back of the engine that the tube screws into. 1958 it is under the 1/8" pipe plug in the center of the engine. BTW these are both under the side cover.

There are others but I will stop there.

Is the oil leaking out below the rocker shaft on the number one rocker? Excess wear of the rocker and shaft can cause oil to leak out there before making it up to the top hole. If it were mine, I would take it apart and look for excess slop/galling between the rockers and shaft. If nothing is out of the norm, I would reassemble and run it, and try to keep the RPMs under 6,000 (just kidding, but you get the gist). You have some oil coming out of the hole so you should be just fine.
Carl

Dave, do you have a picture of the restrictor orfice?

The overflow tube was never originally pinched at all and flowing lots of oil. I pinched it almost fully off in the hopes that the flow restriction might force the oil up to the #1 area. The rockers are not allowing the oil to flow out around the bushings in any manor that makes them look worn out around the shaft. It is possible that someone in the past had replaced the rockers and used a different year. I will take it off and look to see where the groove is in relation to the other rockers. All orifices are clear, i already ensured that was checked.

What year engine are you working on?

Don, I will get you a picture.

1955 235.

Did you confirm the tube behind the side cover was clear?
If so the next thing up stream that can cause low oil flow would be the rear cam bearing being put in wrong. Oil needs to be transferred from the rear main, through a passage, around the cam, through another passage to the restrictor fitting/supply tube.
If the cam bearing is installed incorrect it will block one or both of the necessary transfer holes.

Tube behind side cover.

I'll delete this if it is not helpful. These are the best photos I have behind my '55 235 side cover.

Edit: More detailed photos of the line connection

Brad

no i never took the side cover off. Due to the amount of oil running from the other rockers (equally soaking the tops by flowing from the holes) and the oil flowing from the oil supply tube that joins the 2 rocker shafts i think no other obstructions could be present before the rocker assembly. It is a possibility but the oil flow to the top of the head appears to be very high. Its just that one rocker pair.

Its almost like the oil cant get past the second last stud to get to them very well.

Here you go.
4 pics. the last one shows how some drill out the orifice for more oil.

Thanks Dave. When the fitting is drilled bigger does it send to much oil to the top?

The only side effect I have seen from getting to much oil to the top end, is keeping the valve cover from leaking.
It seems like there would be a problem with flooding the valve stems causing oil consumption but I have not seen this.

One trick we used on the small block V8's to prevent valve cover flooding was to deburr all the drainback holes with a die grinder and eliminate any restriction to the oil getting back to the crankcase. Using positive valve stem seals at the top of the guides will control any tendency to burn oil, but if that's done, the original-equipment O ring seal on the lower valve stem groove and the sheet metal shroud over the top of the valve spring needs to be eliminated. Otherwise the valve guide gets starved for oil and it wears out in a hurry.
Jerry