VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 Installing camshaft gear in 1937 216

(Note: this was also posted in the Mr Goodwrench forum under Mechanical as a reply to a similar topic)

Per the 37 shop manual there should be .003 maximum clearance between the cam and the thrust bearing plate. I find the current clearance to be .016. Because of other problems at only 300 miles, I had to disassemble the engine, so the cam is off, and the gear has been pressed off. In talking to the machinist, he thought there was suppose to be an inner ring that is .003 thicker than the trust plate that would limit how far the gear could be pressed on. I am not aware of this and my parts books do not show it. He admits, he may have seen it in later/other engines. He had a 1940 camshaft and pressed off that gear and it didn't have the inner ring/shim either.

Our dilemma, is how to press on a new gear with .003 clearance? He says the usual means is to press it on (but with a press, all of a sudden it just snaps/slams home as far as it can go...no clearance). Then holding/supporting the cam gear, smack the end of the camshaft with a hammer as if trying to remove it, and create some clearance.

I suggested he place a .003 shim in position and then press it on. He said I'd never get the shim out...it would tear since it was so thin. Then we talked about a .002 shim and the hammer smacking to loosen it enough to remove the shims.

Now, ignoring all of the above, what is the correct way to press on a camshaft gear with .003 max clearance at the thrust bearing.

Also, the parts books show a gasket for behind the thrust bearing. I have never encountered this gasket, and I don't understand what its purpose would be anyway. In addition, the 1937 shop manual never mentions this thrust gasket in the process to determine how many gaskets to place behind the front engine mounting plate, so that the camshaft thrust plate is level with the collar of the crankshaft.

Any help is appreciated!

Well things changed over the years. The basic parts were used from 1937-1954. In 1937 the gear was pressed on until the spacer could turn freely and the clearance would be between zero and .003". The gaskets, one to three, were used to correctly line up the cam gear with the crank gear. (I usually just inserted two). Than things changed in the later years. The hole in the thrust plate was englaged and the spacer ring was inserted inside the hole. (the ring came with the new plate). Then the gear was pressed on tight against the ring and the clearance should be between .001" and .005". In the later years the gaskets were no longer used.
The plate with the ring replaced the original plate only back to 1937. If I were working on your 1937 I would cut a thin paper gasket and insert it behind the plate - if none came with the gasket kit.

What is the purpose of the gasket behind the thrust plate? it doesn't seal anything. Is it for clearance? I don't recall seeing one in an overhaul gasket kit.

Do you have a part number (and year of the parts book) for the thrust with the clearance ring? Or simply, where can I get one? Is it used in other applications? The plates I have do have a larger hole, but I assume that was just so it would clear the woodruff key in the camshaft.

Wthout the clearance ring...any ideas how to install the gear with proper clearance as indicated in my original post?

My machinist uses and air operated hydrualic press. Should another type of press be used, or will same result occur...all of a sudden it slams into place with no clearance? Should I drill and tap a bolt into the end of the camshaft as you describe elsewhere?

The gaskets were more or less of a shim.
The plate with spacer came along in about 1955....didn't go back and look in all the books but it is listed in the 1959 parts book. Part #3707916, description thrust plate with spacing ring.
It listed in Chevs of the '40's catalog. They use the number 3702305, plate and spacer....price $8.75 in my 2 year old catalog. The part fit upto 1962 and I would bet the one they are selling is an after market one that may be available in a parts house.
would tap the gear on with a driver that would contact the metal hub of the gear. Stand cam verticle and you will find that it will go one easier than you think, especially since its alreay been installed. Just tap it till its snug and ignor the .003" as that was the maximum. Just so it turns without force.
Why is the engine torn down for the 2nd time?

If the plates have a larger hole than the shaft and you know a good machinist get him the make up a spacer that fits over the shaft and inside the plate .003 thicker than the plate and assemble the shaft leaving the spacer in place. It will make no difference to the performance of the engine and there is only 2 or 3 people that know its there.
Tony

I just used one of the Chev's of 40's thrust plates. $9.25
It is the newer style with the ring that provides the clearance to the thrust plate, so you just press it until it seats all the way down.

Even with this new thrust plate, I suspect I should still check the way the cam and crank gears mesh and install the gaskets as shims as per the shop manual?

I've also used an aluminum cam gear. Do I need to change anything about the oil nozzle (angle or size of hole) when using the aluminum gear?

In the later years when the spacer ring was used they no longer used any gasket. If it were mine I would use one gasket and see how things look.
If your using an aluminum gear be sure to use a new steel gear. In 1949 the timing gear oiling was changed from gravity feed to pressure feed from the front cam bearing. The oil feed hole in the nozzel was also enlarged by 4 times the "book" says for more oil supply to the gear. At that time the original nozzel was replaced by the nozzle with the large hole for replacement on older engines. If I remember correctly the opening went from 1/16" to 1/8". Probably wouldn't hurt to get a little more oil to the aluminum gear.
The aluminum gear (or a 1940-53) gear isn't exactly correct for a 1937-39 engine. The fiber gear was changed slightly to alter valve timing in 1940 (and again in 1948) for better high speed performance. I have the later (fiber) gear in my '39 and seems to work OK. Chevrolet said the use of a later gear in a 1937-39 would "up-set" the valve timing.
I do have the gasket thickness in my head as its been asked several times.

Some food for thought.....the other day I was looking at some older Service News. They said the the oil slinger on the crankshaft (timing gear) should be discarded when a new seal in installed in a 1937-38. The new better seal runs too dry (the original was leather) and needs the oil for lubrication.The 1939-1962 did not have a slinger. The 1955-58 V8 had a slinger and it was discontinued in 1959.

Thanks Gene,

Hadn't considered the later gear may be timed differently. I read about too many failed fiber gears so I was strictly after reliabilty. I suspect even a new fiber gear bought these days might be based on the newer timing design as well. I'll compare a few gears to see if the cam is that visibly advanced. If the keyways are off by a lot, I may rethink this gear as I want it to behave as close to original as possible.

If it were your car, would you open up the nozzle as big as 1/8"? This sounds large but if indeed gravity fed would only be dripping out anyway.

I indeed have a new matched crank gear. Are the aluminum gears really that much louder?

I wouldn't worry too much about the timing of the various gears. At one time Chevrolet offered the original gears thru parts. Eventually they were all combined and the later were listed for all.
The 1937-39 216 had lots of power at lower RPM's. The timing change brought the power curve up to the higher RPM's. Chevrolet did this again in 1948 so you will get both changes.
Just noticed in the parts book that the opening was increased to 1/8"....I knew I saw it some where. All nw nozzels purchased for a 216 or 235 were the same with a 1/8" opening in the later years. If it were mine I would enlarge it for the gravity reason alone. If for no other reason the gears would get the cold oil faster.
It was common years ago for the timing gears to run dry due to the passage on the back of the front mounting plate filling with sludge. Owners would come in at the end of the winted complaining os a clattering noise in the engine. We used to use various solvent flushes to clean them out ....if you were lucky it would work. The biggest cause of the fiber timing gear failure was the lack of oil. Once they went to the higher pressure for full pressure oiling (and the oils got better) the timing gears lasted much longer.
I had a 216 that the P.O. installed an aluminum timing gear in. When the engine was cold you could easily hear the timing gear whine. When the oil warmed up and fed the gears it was fairly quite. There again I would't worry about it.

Thanks Gene,

You've addressed all my concerns. I compared 5 gears from 37-53 to the aluminum gear and could not see a difference in the keyway position with the naked eye so the timing advances they made are likely pretty minor. With my 4:22 gears it might not be a bad thing if the power band is a couple hundred RPM higher...

Thanks again!

Are your sure that you have a 4.22. The US straight axle cars had a 3.73.
The stamped axle code number will be either a C or CB for the 3.73. The 4.22 will be either not stamped or a B.
On US cars the number is located on the right side of the front nose of the housing, just above the center rib......Forward of the right upper pinion lock set screw.
Would suggest remove the diff. cover, either counting teeth or reading the stamped number on the gears......From what your all doing I suspect you plan on inspecting the gears any way.

It indeed has a B (looks like wavy D) stamped into the pad on the top of the pumpkin. The 38 Canadian shop manual shows all Canadian Pontiacs and Chevs supposidly shipped with the 4:22 except the trucks. They must have been cheaper gears! I have a spare rear end from a 38 2 door Canadian Chev sedan with knee action and I counted the gears and it was 4:22 as well. Like you suspect, I'll have it apart so will count.

So, besides the green 216 engine, the automatic choke, the cable operated column shift, the under-dash emergency brake lever, the Pontiac "shaped" front end and running boards, the 1937 Chevy door handle design, Pontiac instument cluster, Pontiac hubcaps made to fit the chevy rims, and now the rear gears, it's the "same" as the Chevy...or is at least a Chevy with some weird Canadian bolt on parts...

I'll take some photos of the cam gear oil nozzle before/after drilling it out and post them.

Perhaps the Pontiac Engineers like the lower gearing. The US real Pontiacs had 4.37 ratio rear ends. 1936 and prior had 4.4 and 4.55.
The 4.22 gives a real flexible high gear between 10 and 60 MPH Also they are real hill climbers.

Gene, my engine is assembled with a new style seal, but not painted or installed yet. would you suggest I pull it apart again and remove the slinger in my 37? Do you think it really mattters when only driven a few thousand miles a year?

To be honest with you I wouldn't bother. The new neoprene seals may squeak if they run dry but running some WD40 down behind the balancer will cure that.....and I am sure many have run for years with the modern seal with no problems.
That seal was used for both 6 and 8 Cyl. engines up into the '90's.
If you havn't installed the balancer yet put a thin film of grease on the seal or balancer shaft.