1961 Chevy 235engine. Getting ready to test on the engine stand and wondering why the rocker arm oiler tube might have been pinched closed?? This was the engine that came in my 53 from 20 years ago and seemed to run normally. Should I just cut off the end to restore the flow?
Probably not. You will need to find the stamped engine serial number behind the distributor and research it to figure out what shape oil connector the engine needs. There are at least 3 styles that fit various years of 235, depending on whether the rocker shafts re "full pressure" or not. The original oil supply circuit for a 61 engine will have the pinched-off tube as standard equipment unless an earlier style rocker arm assembly is being used. Jerry
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I think that a lot of people think oil should gush out of the rocker bleed holes, so they pinch off the overflow. The truth is that only a dribble is needed to lube the shafts and pushrod socket. Also I don’t think people realize once the engine RPMs come up and the oil pressure rises there will be much more oil coming from the bleed holes.
Next time I have the valve cover off of my full pressure '53 full pressure 235, I plan on turning in the idle screw up gradually to 2,000 RPM or higher if i dare without a load on it to see what's going on with the oil coming through the rocker arm holes, just for giggles and that other thing that commonly goes with giggles. I will get back here with the results. My tube is not pinched in any way. Totally stock.
Last edited by 52Carl; 02/11/202211:15 PM.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
You might consider blocking the wind off of the fan if you're going to run it that fast with the valve cover off.
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You might consider blocking the wind off of the fan if you're going to run it that fast with the valve cover off.
Good point. As soon as we start seeing wind blown oil, we'll bring down the RPM. I have a feeling that this adventure will be anticlimactic, going from barely dribbling out to really dribbling out. I base this prediction on what happens when one has a horrible valve cover leak, where it just dribbles out even during a hot run.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
This probably old hand for many, but there is a steel line that pulls oil from the rear cam bearing journal and runs to a fitting about middle top of the lifter area of the block right behind the side plate. This line is what feeds oil to the rockers. Many 235 motors ran without an oil filter, many ran with an oil filter. No matter, this line often got gummed up on the Id of the line, sometimes to the point of clogging and no oil to the rockers. When it got partially clogged, many thought pinching the overflow would help keep oil from overflowing and keep it where it was needed. So you often find them pinched. As noted above, when gm altered the oiling in 59, all of the overflows were pinched. I don’t know that there is anything inherently harmful in running the pinched version in a pre 58 motor.
Swami29 If you open it up you'll see oil just gush out of there,mechanics would pinch that till all rockers oiled,hopefully ,one of my old teachers used the hammer method on babbitt he would say if you get 10 or 12 pounds pressure your doin' good then he'd just laugh!!!
