VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1933-1936 1934 Master Oil Pump

I read in some of the postings about a gear-type oil pump being used in the 1934 engine. Can any one tell me more about this type of pump? Is there an advantage of the gear-type pump over the vain-type pump, and is it still available any where?

The gear pump was a later replacement made in the late 30s or early 40s. The original pump was a vane type. Advantage in the gear pump was higher pressures were possible. I understand that the vane pumps had higher flow rates but produced lower pressure. Both will work fine.

A word of warning when using the gear type pump
I installed a nos unit in my original 34 Master engine and it was fine for a number of years. The clearances between the pump body and the crankshaft counterweights is about 8 to 10 thou. and eventually the end play in the shaft exceeded this.
The 1st problem was the oil line working loose with the shaft tapping it backwards and forwards. This I had to fix on the side of the road in pouring rain. In 2 hours was back on the road.
This pump eventually let me down with no pressure. It appears that when the shaft hit the body it bent the pump housing, which then caused the gears to run out a few thou, which cut a groove in the bottom plate and eventually lost pressure.
The pressure on the oil guage was no different than the original vane pump
If you do install a gear pump, make sure you grind at least 20 thou of the corners so that it clears the counterweights.
Chris

Chevguroo, Was your gear pump a genuine Chevrolet replacement? There are some off brands that were made years back also. I have had one in my '34 for years -with a '36 crank shaft with more weights and all has been fine....................Bill M.....the gear pump kit was made by Chevroler using a 1937-39 oil pump-pluus the screen and necessary plumbing hadrware.The 1934 kit only fit a 1934.As Chip said its not completely necessary but if you drive the car faster its just good insurance.Before WWII Chevrolet also made an oil pan change over kit for '34 Masters that consisted of a '35 oil pan with the pipes jeting oil direct to the dippers,the improved oil pump and wider dippers.Very rare-never have seen one.The wider dippers alone are an improvement......The Filling Station has a 1933-34 gear type oil pump listed in their catalog for $159.50..have no idea as to what it is.I have seen NOS ones in the G&D for less than $50.00 ---The chevrolet part # was 604508 for the oil pump kit.

Chev Nut
The oil pump was sourced from US but was not a genuine Chev product, can't remember the brand.
Interesting though is the reconditioned original pump runs around 15 lb when travelling at 35 mph, which is far better than the nos after market pump ever did.
The car is original, never been restored, the engine is still running on the original pistons and main bearings, and has just clocked over 100,000 miles. The centre main has now run out of adjustment and having owned the car for 28 years, it's probably time for an overhaul.
We are taking it to Tasmania in November this year and will travel well over 5,000 miles
Chris

chevguroo,I never drove mine with the original vane pump so have no pressure readings to compare.The gear pump reads 16 lbs. with 10w-30 oil fully warmed up.Thats better than my '39 which would be at 14 lbs. at that point.The 1937 Engineering Manual describes the "new" gear pump as offering a smoother flow of oil and greater pressure at high speeds.And the pressure is described as mataining pressure to maximum speed , rather than reaching a peak and then dropping off as with the vane pump.Sounds good to me but when driven at normal speeds I sure either one will suffice.

Thanks for the great information guys. This Chevy Chatter discussion forum is absolutely wonderful!!!! I wish I had discovered it earlier.

I would like to respond to the comments on oil pumps.
Vane-type oil pumps were used in the late 4 cylinder cars. With the introduction of the 6 cylinder engine in 1929 a pump with the same capacity as that in the last 4 cylinders was used. But GM soon realized the inadaquacy of the small pump in the 6, and enlarged the capacity by increasing the height of the vanes. In 1930 and again in 1932 further increases were made. Finally, in 1937, GM introduced the gear-type oil pump. Apparently during WWII, GM adapted gear-type pumps as replacements for the early 6 cylinder engines. All of the replacement pumps were identical to the 1937-39 stock pumps except for the top end of the pump body and shaft where it fit into the block and mated with the distributor shaft.
About 3 years ago, C&P Automotive began manufactured gear-type oil pumps identical to the GM replacement ones. The capacity of these pumps is several times that of the largest of the vane-types. A pressure relief valve is integral to these pumps and begins to release at about 60 psi.
Our experience is that with a stock vane pump (1932 capacity) in a 1929 engine, idle pressure ran at about 3 psi and on the freeway at 55 mph, the pressure was about 12 psi. (all measured with the engine at normal operating temperature). With our gear-type pump, idle was at about 12 psi, and at 55 mph, we recorded about 25 psi. Cold, at an idle, the guage was barely pagged at 30 psi. but quickly dropped below that as warm-up began.
I hope this helps to answer some of your questions.
Bill
C&P Automotive

Billy, Thanks for the reply on oil pumps.This makes me even more convinced that a gear pump is a worthwhile improvement.This is great for those that do a little serious driving with there old cars.Would be especially important in the 1932 and newer.Prior to that there were no bearings pressure lubricated but the positive supply of oil is still of importance.Do your gear pumps come with the '39 type screen and the plumbing necessary to install as the Chevrolet kits did??....for more discussion on oil pumps read thru Antique Mechanics thread on rebuilding his 4 cyl. engine.Its under Radios,Tools Accy.

There was direct pressure to the center main bearing in 1930. That was a "first" for that year. :cool2:

Sorry-correct-forgot about that. :confused: :confused:

bill, jyd, & chev nut,

so, is there agreement that bill's gear pump would be an improvement to '30 & newer, then?..

epi

The new replacement pumps may or may not be an improvement. Higher flow rates keep the oil in the pan more agitated and at a lower average level when running at speed. Without a filter crud can more easily be drawn into the pump and then through the oil distribution system. More oil on the head can lead to leaks at the valve cover. Higher flow and higher pressure may also result in leaks at the front and rear main bearings. It depends on the condition of the bearings, wells, distribution holes, etc.

The higher flow will give more positive lubrication and more internal cooling. Those are mostly good. It will also help wash out the bearing to part spaces. The higher pressure on the bearings gives a teeny tiny bit more resistance which you will never know.

The original pumps have been used for millions and millions of miles so they work too.

Remember these old Chevys are not daily drivers and the miles don't roll up on them like years ago. They also don't get driven on the freezing, rainy, dusty, torid days as in the past. They really have a pretty easy life in their semi-retirement. Sorta like may of us.

chip,

well said...thanks for the clarification...

epi

Lets call it an opinion.....The gear pump in my 1934 has done well.There are no oil leaks, even though the engine has no front cover seal or rear main seal.Oil to the rocker arms is more or less metered and either pump gives them good supply,..My cars are used for the long , fast driving that they were never designed for so I fell more comfortable with giving the Chevrolets marginal oiling system all the help I can for this use. For the trailered car or short tour car the vane pump is more than adaquet providing its in good shape--vanes not worn vane springs in good order etc....and todays improved oils also give better protection which is also helpful.

Yes, Gene, now there is a real clarification! Opinions are like .....many other things around here, that get confused with the facts. Of course I only supply facts! don't you know? and I guess the oldtimers that drove the early Chevrolets all trailered their cars from the East Coast to the West coast on a regular basis, or from Missouri to Montana and back twice a year up hill... both ways ....and in a rageing snowstorm,...... passing V/8 Fords ,broke down on the roadside, by the dozens! running on coal oil and useing bacon grease drippins' for oil,....( at least that is one of the stories my uncle tells me!)....I know he would not lie because he is a VCCA member!

I think that we have shared many of our opinions here.I do respect all and it may some times sound like a debate but I believe it a way for all to learn or at least to consider other things....There has been "debates" on whether or not to use water or a anti-freeze mixture, to run a thermostat or not, use a detergent oil or not, oil filters, cast iron pistons VS aluminum,rod inserts or babbited rods, ....and both sides are represented so an uninformed person can make a decision...I hope :confused: :confused: PLUS it keeps us out of trouble at home

I agree completely, I enjoy the dialog here better than.. ...???

what was I going to say? I am always forgetting about something these days! Oh Well!..... never mind...... I also confuse the forum with a live chat room at times.....