VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1933-1936 Rocker Arm oiling confusion...

Hi, fellas-

As part of freshening up the old '33 for the touring season, I decided it was time to pull off the rocker arms and file the depressions off the bottom where they contact the valves, so I could get a true reading with the feeler gauge.

As I was laying out parts to clean up for reassembly, I noticed something that struck me as maybe wrong.

In the middle of the top of the Head, you have the "T" where oil is brought up on top from the oil pump. It sends oil down the rocker shafts.

Going to the rear 3 cylinders, there is a baffle or restriction in the little spacer that connects the "T" to the rocker shaft. It has an orifice maybe about 1/16" in it. But the connector/spacer that goes to the front 3 cylinders is wide open.

Couldn't decide if maybe I'm missing that baffle & orifice going to the front 3 cylinders, or what.

Then I thought- well, maybe that orifice is in there so that oil will be forced forward when the engine first starts, because gravity is going to carry it to the rear (which slopes a little down-hill). But I can't convince myself of either answer, so I thought I better come to this "Well of Wisdom"

To quote the 1933 Engineering book "The resrtiction in the sleeve leading to the rear rocker arm shaft prevents over oiling caused by the inclination of the engine in the chassis". :) I have had my '34 for over 32 years and never gave it any thought.Now we both learned something new today

Well, hurray! I was actually right (amazing!), it IS because the rear slopes down-hill. Seemed like that might be what was going on, but I was just guessing. Now we know. Thanks for taking the time to look it up. I can reassemble with confidence......

Hi Guru,
Just as an aside it is not necessary to hand file those rocker arm ends. While confronted with the same situation on my 28 several years ago I recalled that the old valve grinding machines of the fifties had a neat little attachment for grinding this radius, so I looked up Snap-On's website and asked if that feature was still available. The answer was yes even their latest machines have the attachment and they mailed me a brochure that illustrates this. It does a much quicker and more accurate job but you may have to convince the shop guy to find and use the attachment.
Herb

Explanation of why there is a need to grind.

When I click on "explanation of why there is a need to grind" I get this instead: "Only administrators or moderators may perform this action - and that's NOT you!"

"Please use your browser's back button to return." :( :( :( :(

Okay, try This

Okay, that worked!

Come to think of it, I think reading that posting in "School is in Session" back when, is what put the idea in my head of needing to grind those rocker arms, in the first place.

I'll report back if I get rid of all that valve train clatter as a result. I should get this job finished today, if I ever walk away from this computer long enough to accomplish anything!

Well, I promised to report back on the results of my rocker arm grinding adventure.

Herb, I also meant to tell you "Thanks" for the tip on Snap-On. I just used a grinding wheel to knock the high areas off around the depression worn in the bottom of the rocker arm face, then put each one in the vise and filed a slight radius on it. Only took maybe 1 to 2 minutes per rocker. Then I polished it off with some 320 sandpaper.

Then, back together. I probably should have found some new rocker shafts, they were showing quite a bit of wear, but I just cleaned them up and re-used them.

To adjust the vavles, I meticulously followed the instructions in the Repair Manual (for a change!). Set things up finger-tight to get her running, then let it come up to temperature. Then set all the valve stem / rocker gaps. At that stage, I was disappointed, because there was still a lot of valve train clatter.

This is the good part - as the Book says to do, I put the cover on, and ran it for several minutes at higher speeds (I drove it up the street and back). Then I did the process all over again. Shut her down, readjusted all the gaps to the factory spec (not looser, like so many guys tell you to do). .006 on the Intakes, .008 on the Exhausts. Tightened everything up, and WOW! It was quiet! It was so quiet, that now I can hear the rods and mains talking to me.... never could hear them before, the valve train was always making too much noise. Not in a bad way, you understand, just that now you can hear the rest of the engine 'innards' working.

Of course, while I was playing, I cleaned and gapped the spark plugs, the points, and readjusted the carb settings, checked timing, etc.

She has never run so quietly, or so strong. I was genuinely surprised that there was such a difference by re-setting the valve gaps a SECOND TIME, with the engine warmed up, and run in good. Wife always tells me I should follow the directions. Glad I tried it!

I have only read part of the link back to an earlier "school is in" and beg to differ on the problems with worn guides. Firstly 1 suggestion was no problem with ex guides worn, what about exhaust contaminents in lubrication system and oil.
With worn inlet guides would also allow oil to drain down stem causing smoke at start up as well as lean mixture.
Just food for thought from a fool.

Hi tonyw,


If you had read the thread completely you would have discovered there is NO oil around the valve stems on a Chevrolet 4-banger. Your theory IS correct for the modern (29 and later) 6-cylinders.

I stand corrected.
Not knowing the 4 banger setup and only briefly reading the thread did not help my cause.
Thanks Ray

Chevy Guru

To one guru from another guroo
I've had my 34 Master for 28 years and set my valve clearances by the book as you did. I found I was getting burnt exhaust valves about every 15,000 miles or so.

I did a bit of homework and asked some "experts" with the following results.

The petrol octane was around 70 to 80 in the 30's, probably even lower. The octane these days is over 90. I'm not sure what you blokes use in US. This extra hard on valves because of the extra heat generated.

The experts suggested I enlarge by valve clearances to 1 or 2 thou over standard, which I have done. The valve gear was noisier, and with my Chev having now clocked up 100,000 miles on it's original engine, it's probably extra noisy.

BUT! I have done over 20,000 miles since the last re valve and it's still going fine.

What is best. Noisy valve train, longer distance between valve work, or nice and quiet and shorter distance between valve work? Only each individual can choose that.

As I travel about 3 to 4,000 miles per year (I will be doing over 4,000 in November alone) I chose the noisy valve train.

I also open the vales a little on my 28 for the same reasons

Food for thought.
Chris

Chris,If you set your exhaust valves on your '34 Master as Chevguru did on his '33 you will burn the exhaust valves.The exhaust on the 1934 and up are set at .013" to .015".I have been runing close to the .013" with no problems with mine.

Chevgene
I didn't use the 33 specs, I used the 34 Master specs which are as you suggested, but I added another 2 thou clearance.

I just wanted to let others know the situation. It is the 'high' octane fuel that burnt the valves as they were original nos Chev valves which were manufactured to run at a lot lower temperature. Most people down here convert to modern valve equivalent and run unleaded which has a 96 octane.

The Chev specs are too tight for modern fuels, which in turn runs at a lot higher temperature, which burns the valves. The extra 2 thou gap alleviates this problem
Chris

The exhaust valves were one of the weak points of the Chevrolet engine.This problem continued until 1954.The 1954 Power Glides used what they called XCR exhaust valves and were of much better quality.Often lasted as long as the engine ran.The best valves to use in a 1950 and up engine of any size is the small block V8 valves.They were of a still better steel.They can also be used on '41-'49 with a few changes...I don't know whats available for older years but I found a set of Thompson "Stelite" exhaust valves for my "39 which I recently installed along with a new head......My '34 has Genuine Chev valves but their later varsion with the modern U type keepers.

Gene will the new valves and keepers work with the old spring caps? and visa-versa?

If your refering to the up-grade for the '34 Master-no-The 1935-40 spring caps must be used.....If your refering to putting V-8 valves in a 1950-62 6 -no the valves are the same as well as the keepers and caps.....If you install the V-8 valves in a 1941-47 The caps from a '48 & up must be used as well as the O ring seals--and seats must be groung to 45 degrees (were 30).The same valves also fit the New '63 and up 6 cyl.Keepers are the same since 1935-all 6s and small block V-8s.