The Stovebolt Site Forums The Shop Area Engine Shop 1955 Rocker oiling

My "Pushrod" thread morphed into a discussion about possible lubrication problems at the rocker shafts. As I noted in that post, I ran the engine just tooling around for about 5 years. It was quite "Clackity". I now know why. Shafts worn bad, rockers worn bad and a few pushrod cups worn bad.

Here are my findings so far...

See the pics, they show the wear on the shafts and two of the rockers. Note the raised dimple created on the inside of the rocker bores.

The oil line from the block to the passageway to the head seems clear. I ran fluid through it in the parts washer and fluid flowed freely right away. No restriction noted.

I blew some brake parts cleaner through the passage way in the head and it flowed right out. No restriction noted.

The oil tube is pinched. From what I've read that's an "after factory" modification to force more oil into the rocker shafts. I did note that the pinch does not stop flow. I could blow right through it.

So, my questions are...

1. Will running the oil pump with a drill be adequate to determine if oil is flowing up to the head?

Was planning on running the pump without the oil tube in the side cover to see if there is oil at the tube, then through the tube into the oil tube (without the rocker shafts in place) and finally with the rockers and shafts installed to see if oil is present.

2. If there is no oil to the tube fitting in the side cover, how do I determine the restriction down in the block?




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rest of the pics...

I can only answer question #1. The drill will give you plenty of oil pressure to see the lubrication.

Your shafts are really beyond repair. You can still find replacement shafts on occasion, the best option my be to find a complete replacement assembly.

I had a rocker assembly rebuilt at Rocker Arms Unlimited, the work was top notch. I thought it was a little pricey until I started pricing the parts separately. Having assembly rebuilt just seemed the best action.

The oil tube is restricted as to limit the amount of oil at the top end. The rocker assembly doesn't really require full flow.

https://www.rockerarms.com/

Oswald - When you tested the rocker oil tube piece, did you block the hole on the inside of the collar that rides on the rocker shafts? That's where the oil transitions from the feed tube to the shafts and that should be unrestricted. The pinch off of the tube beyond where it feeds oil through the collar should restrict flow out that tube. To test if its actually restricting anything, the hole in the collar needs to be closed off.

Should be able to do that with your finger inside the collar while you blow through the feed tube. No air flow or restricted air flow would be the sign that the pinch off is doing it's job.

GDADS, Have not tested yet, hopefully today. Are you talking about the hole in the oil tube after the pinch? I did not, but that's AFTER the pinch anyway so I'd assume there will still be flow through the pinch. Is closing the pinch so there is little or no flow out of the tube a good idea? Meaning oil has no other path than through the shafts and rockers?

Oswald - Not the hole in the tube beyond the pinch.

Where the tube merges with the side of the collar, on the inner side of that spot is a hole that the oil feeds from the tube through against/around the rocker shafts that fit inside that collar. Below is a screenshot from a 1955 Chevy Shop Manual that shows the oil flow (solid black including down inside of rocker shafts) from pump below and out the discharge end of the now crimped off rocker shafts collar feed. See the red arrow for where the hole I'm describing is.

The idea with pinching off the out feed tube came along in later years to improve a lack of oiling to the rockers, so yes, forcing the oil to the shafts and rockers.

There is a rather convoluted oil circuit to get lubrication to the rocker shaft, and it can get clogged easily. Older engines with an oil line under the pushrod cover connected to the middle of the rocker shaft got their oil from the rear camshaft bearing. Later ones such as yours use internal passages in the block and an oil connector that plugs into a hole in the cylinder head.

Both systems can be bypassed by running an external oil line from the oil pressure gauge port, around the back of the head, to the 1/8" NPT port in the middle of the cylinder head on the passenger's side. Use 1/8" OD copper (NOT PLASTIC) tubing, the same type that is used for aftermarket oil pressure gauges. The small ID of the tubing controls the volume of oil flow to the rocker shaft very well.
Jerry

Jerry, My block is a "55. It has the tube you describe going from the rear cam bearing to the head inside the pushrod cover. That line was clear, as was the passage from the line through the head and to the rocker shaft.

Try spinning the oil pump with the line disconnected at the back of the pushrod chamber. You should get a good flow of oil out of the block. If not, the passage to the cam bearing is clogged, and you would probably need a complete teardown to a bare block to clear it. Sometimes putting high pressure air into that port at the back of the block will clear the clog, but I don't like to do halfway measures. The external line works, and it's been done that way for 50+ years.
Jerry

OK, so I did the oil check as I described, mostly. Drove the pump with a drill and amazingly as soon as I felt it load up... Bam. A 4' stream of oil accross the floor. Forgot to plug the oil line to the filter, oops! Anyway, oil flowed to the fitting that enters the pipe, great. Installed the pipe, did the same thing and Oil quickly got up to the head. Figured oil delivery is OK. Why the rest of the upper valve train failed. I don't know. There were some rockers and holes in the shafts that were clogged with junk, but not all.

As far as the oil tube GDADS mentioned, yes with all of the holes covered, the end, the hole in the tube and the opening inside the bore. There is leakege through the "Pinch" Should I pinch it completely?

I guess I'd ask "how much leakage?". If you have the hole on the inside of the collar open and flowing to the rocker shafts so you can see oil dribble out of each weep hole on the rockers themselves, there shouldn't be a need to further crimp/seal that tube.

On the flip side, if you're not getting oil weeping from each of the rockers under regular pressure, or very little (knowing that you've already checked the rockers for obstructions), then you could further crimp it to try and force more oil through the rocker shafts.

To address Hotrods clogged passage the cam bearing... One thing I did not mention is that oil was oozing out from all of the lifters. From what I can find on the net, aren't the lifters fed by the passage from the min cam bearings as well? And, isn't the fitting to the tube behind the pushrod cober fed from the same oil passage?

If I am correct the passage ways to the cam bearings, the passage to the lifters and the passage to the oil line must be clear, right? I must sound like I'm beating this to death so thanks for your patience. I've always believed that you can fix something it you understand how it works. If you don't understand how something works you're just throwing stuff at the wall to see if it sticks.

What was the original application for the engine, and when was the block manufactured? Prior to about mid-year 1956, the only engines with an oil gallery connecting all the lifter bores were passenger car engines with Powerglide transmissions. They ran hydraulic lifters. Trucks, and standard trans cars did not have the big gallery bored front to rear to oil the lifters. Around 56/57, all blocks got the big oil passage to the lifters, regardless of transmission or lifter option.

Engines with the oil line from the rear cam bore to the head DO NOT have that big gallery, unless they also have hydraulic lifters from the factory. The engine/trans assembly I just acquired a few days ago turned out to be a 1953 passenger car 235, with a serial number prefix indication it was originally installed in a Powerglide-equipped car. It was married to a SM420 truck 4 speed transmission for an early 1950s truck with a torque tube rear end. Definitely a mixmaster! There's no telling how these old engines and vehicles were swapped around in the past 70-something years!
Jerry

Vin on the engine vin is "0769813 F55Y", casting number is 3836233. Head is a 3836850 dated C 1 2. It's in my '54 so it's not a marrage from the factory. Given the multitude of paint colors I'd think it was a rebuilt at one time. Lifters appear to be solid, no spring deflection when I pish down on them. Might have been a purpose built rebuild, I don't know.

Oswald - The block casting# 3836233 matches 1955-57 Chevy 235’s with the low position water pump.

The “F55Y” stand for built at the Flint Plant, 1955 model year and a passenger car 235 original equipped with an automatic (Powerglide) transmission. As such, it would have originally been built with a hydraulic cam and lifters. They can and do get rebuilt with solid cam/lifters as they function fine in the same block.

Your head casting# 3836850 indicates it’s actually a “261” truck engine head. The head date casting codes C 1 2 stands for March 1st, 1962.

Definitely not what was married together at the factory, but could be a very nice engine depending on how it was built.

BTW- - - - -it takes about 3-5 minutes of constant pressure on the pushrod end of the rocker arm with a long lever to make a hydraulic lifter collapse- - - -it doesn't happen immediately.
Jerry

I decided to just take a pic of the lifters that are in the engine. they do not appear to be Hydraulic (no retainer) and they don't look like the "milk can" type that are offred as replacements. I guess take a loo and let me know what you think. Can add pics of casting numbers and dates if it will help. Thanks!

Most of our current vendors offer the style you have pictured as 1956-62 235/261 "solid lifters". 1955 and earlier solid lifters are advertised as "milk can" style. If these were hydraulic style, they would definitely have the clip holding the inner push rod cup in place. I think you've solved this part of your engine mystery.

With a "mixmaster" engine such as yours, the only definitive way to identify the cam (not the lifters) would be to degree it. The acceleration ramps between the base circle and the beginning of the valve lift at each lobe is different- - - -hydraulic cams have a very short areal of transition, about .003" to .OO5" over a span of about 5 degrees of rotation. A solid lifter cam has a longer transition area that incorporates whatever clearance specification the cam manufacturer provides- - - -usually about .006" to .008" at the intake valve stem, and about double that distance for exhausts, due to the higher temps and more stretch of the valve stem due to heat expansion. Unless, and until that test is done, there's no way to determine what the cam was originally manufactured to be. Solid lifters on a hydraulic cam are usually noisy, and they can cause damage to other valve train components.
Jerry