VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 oiling '31 main bearings

My repair manual says the cam and main bearings get positive pressure lubrication. I thought the main bearings got their oil from the troughs above them gravity fed? Anyway I am trying to clean the galleys (sludge traps) above the main bearing and would like know how the oil system works. On the front main bearing there is a stand pipe in the big center galley and two holes; one goes toward the camshaft and the other down. Also there is a hole that goes forward with a bushing. The smaller galley to the left has a copper line about 1/8” in diameter that terminates in the galley. When I spray solvent in the center galley, and compressed air, fluid drips out around the front main and the first two rod bearings.
Would someone please explain what all those holes, pipes etc do? Should I disconnect the oil lines and blow solvent through them?

The manual talks about a high pressure side of the oil pump going to the gauge and a low pressure section. It would be greatly appreciated if someone could point me to information on this.

Thanks

joe

Do you have a '31 or '32 Repair Manual? The '32 does have pressure lubricated main bearings but the '31 does not. The '31 main bearings are lubricated by gravity from the oil pockets.

my manual is from 1929 - 1932. so i guess i will have to seperate the information somehow. does the '31 have both high and low oil pressure? is the crankshaft drilled?

thanks

joe

All Chevrolet "splash lubricated rod bearing" engines have oil directed to points under high and low pressure. The oil distributor (casting bolted to lower left side of block) is what determines the (splits) pressure. The 1929 engine had only the oil pressure gauge getting the high pressure. This was to indiacte that the pump was performing properly. All other points got the low pressure fed through oil lines. In 1930 the center main bearing got high pressure (and 1931) .
The front and rear main bearing oil pocket also feeds oil to the front and rear connecting rod troughs. The front main bearing pocket also supplies oil to the timing gear oil nozzel.
The 1932 engine had an oil pipe from the center main to the rear main and another to the front main. So then all mains got full pressure oiling.
The first engine to have a drilled crankshaft was the 1953 Power Glide engine.

Hello, as far as I know the '29 to '31 bottom end is pretty much the same. The area you are talking about is called sediment pockets and other telling you what they are that is about all of the reference you will get from the manual. They are pockets formed into the block to catch carbon, grit, and whatever else that can get through the oil pump screen. The pocket fills up with oil and then runs down that copper stand pipe in the middle to oil the main bearing. The top of that stand pipe and the hole that directs oil to the cam bearing journals is slightly below the lip of the sediment pocket so that the bearing is getting relatively clean oil. If you are trying to clean out those pockets try to keep crud out of those holes unless you have your crankshaft out. On my '29 engine there are four copper lines from the oil distribution valve. One on the outside goes up to the gauge, another on the outside goes up to the rocker shafts, one on the inside goes to the connecting rod troughs(sp?) and the last one on the inside goes to the main bearing sediment pockets and the sprayer for the cam gear. Hope this helps.

Thank you thank you chevy nut and beachbum. that really helps me understand this oiling system. the hole towards the bottom of the main bearing just above the cork gasket facing in must be how oil gets to the number 1 and 6 rod troughs?? the crankshaft is in and it is very hard to see if the holes are cleaned properly? i'll do my best. thanks again for taking the time to explain this.

regards,

joe