The Stovebolt Site Forums The Shop Area Engine Shop Rockers

1) The "oil connector" tube on my '56 235 is broken off at the bend on top, past the rocker shafts (the rockers still get oil). Can I plug this "overflow" end to increase oil flow to the rockers like they did with '59 235's or should I replace it? Oil flow and pressure are good with no clogged passages.

2) The rocker shafts have a small intentional flat side machined on them over their entire length. Should this be on the top or the bottom? I can't tell from the service manual.

By the way, I'm restoring a '54 3100 and I couldn't do it without all of the great advice that I've found in these forums.

1) I'd guess that you may pinch the tube-end and not worry about what seeps past the pinch - the tubes were often pinched a little, perhaps to increase oil pressure?

2) When the flat side is down (on the bottom) are the holes on the top? I think the holes on the shafts are supposed to be on the top.

The oil holes are on the same side as the machined flat.

I'm pretty certain the holes on the rocker shafts go on the bottom. This is the area of maximum scrub as the valve and valve train are trying to push the rocker up. I'll bet the machined flat is on the same plane as the lube holes. It would create a small reservoir for the oil to puddle...I could be wrong though.

Stuart

Makes sense to me. Thanks for the quick response.

All 1942 and newer 216/235/261 Shop Manuals show the holes on the top? I'll continue to follow instruction 9 on this page (but, the picture could be wrong).
http://chevy.oldcarmanualproject.com/shop/1954truck/54ctsm0611.html

Somewhere I have a reference in a shop manual stating that the oil holes go down. If you think about it, the overflow is positioned below the top of the shaft and as such oil never actually gets to the top. With the oil holes at the top, the oil cannot get to the holes. Also as stated, the active bearing surface is on the bottom of the rocker and the bottom of the shaft.

I've slept a few times since I had the head off of my 216 but I believe the oil holes were on the bottom. As truckernix advised, if they were on the top the rockers would be running dry for a long time before getting any oil.

Tim (Lederman),


The only holes I see in the picture you linked are the large holes for the support bolts, which aren't' the same as the many small oil holes. It seems to me that if the oil exit hole is in the top of the rocker arm then the small supply hole in the rocker shaft would be 180&deg out, otherwise no lubricant would flow around the fit of the rocker arm.

Stuart

Thanks, Stuart,

That explains my confusion and mistake (and my ill-chosen obstinance).

So, I'll still install the shafts as shown in the picture (and the lubrication holes and flat spot on the shafts are on the bottom - as you all have been saying all along).

Tim

If one looks closely at Figure 3 in the engine section of the 1955 Shop Manual, it can be seen that the lubrication holes are, as logic calls for, on the bottom of the shaft.

Hoyt

Thanks, guys. I don't know what I'd do without you. Now, how about pinching the end of the oil tube off?

It has been my understanding that the primary purpose of the bent tube past the rocker shaft fitting was to direct the excess oil flow back into a drain hole so that oil did not spray all over the place when the engine is running with the valve cover removed. I have never heard a good explanation why some of the oil supplied to rocker arm assembly needed to be bypassed. If the return tube (or what is left of it) is pinched off, then there will be more oil flowing to the rocker arms than was originally intended. Is this a problem? Probably not. However, the oil that flows out of the bleeder holes in each rocker arm could squirt out at too great of a velocity and not properly lubricate the valve stems and poshrod seats, as discussed in the text below Figure 3 in the 1955 Shop Manual in the post above. What does the oil flow pattern look like while the engine is idling. As I recall, there should be a steady stream of oil flowing out of each rocker, but it should not be blowing out with great force. Still enough to make a mess after a few minutes of running with the cover off. If you cannot find a new or good replacement oil supply tube now, I would just partially pinch the broken tip until a replacement is found and installed.

Hoyt

Just my 2 cents but do I remember reading the later 235s were the "High Pressure 235"?

I would agree with Hoyt on too much oil might squirt away from the intended locations.

I see your point. I'm sure that the engineers who designed this had a reason for the overflow tube. Also, I think that the '59 rocker bleeder holes point to the side, not straight up on the rockers to possibly divert the oil away from the valve stems (there is no overflow tube on the '59 oiler). Guess I'll have to splice the tube or find a replacement. Thanks again for all of your help.

If I remember correctly, the mounting bolt holes in the rocker shafts are larger on the top, to accomodate a shoulder on the bolts. But maybe I don't remember correctly- its been a long time since I had one of those apart.

Harvester