BB Oil passages

[John M.]

This is a 67 427-390. Memory test.
To get oil to the lifters the oil pump pumps oil thru the rear main, up to the backside of the rear cam bearing and around it into the gallery that feeds the lifters. Does the standard rear main bearing have a groove all the way around or is the oil feed to the lifter gallery intermittent, i.e. a shot per crank revolution? This car has a problem with the lifters at the front of the engine being noisy, not enough pressure. Everything is new OEM.
Thanks
JBM

[John H.]

Re: BB Oil passages

Starting in '67, a groove was machined in the rear cam bearing bore in the block so oil flowed around the outside of the bearing shell to the lifter galleries, and there was no groove either in the rear cam bearing shell or in the rear cam journal. In '65-'66, the rear cam journal had a groove in it, and the rear cam bearing had a matching groove on its I.D. to provide a flow path. In either case, the flow was continuous (unlike '55-'56 small-blocks, which were one-shot-per-rev of the cam).

'65-'66 MUST have both the groove in the rear cam journal AND the unique rear cam bearing with the groove on the I.D. to get oil to the lifters.

[Joe L.]

Re: BB Oil passages

This is a 67 427-390. Memory test.
To get oil to the lifters the oil pump pumps oil thru the rear main, up to the backside of the rear cam bearing and around it into the gallery that feeds the lifters. Does the standard rear main bearing have a groove all the way around or is the oil feed to the lifter gallery intermittent, i.e. a shot per crank revolution? This car has a problem with the lifters at the front of the engine being noisy, not enough pressure. Everything is new OEM.
Thanks
JBM

John-----


The REAR MAIN BEARING has NO groove on either side.

[John M.]

Re: BB Oil passages

Thanks for the replies.
Joe, no groove on the journal side of the rear main bearing for 67 BB?
John

[Joe L.]

Re: BB Oil passages

Thanks for the replies.
Joe, no groove on the journal side of the rear main bearing for 67 BB?
John

John-----


I was incorrect. For some reason, I was thinking of the lower bearing half. The upper bearing half does have a groove on the journal side. Pictured is an NOS example of the GM #3876085 standard rear main bearing used for 1966-72 big blocks.

[John M.]

Re: BB Oil passages

Thank you Joe and John,
JBM

[Bill M.]

Re: BB Oil passages

'65-'66 MUST have both the groove in the rear cam journal AND the unique rear cam bearing with the groove on the I.D. to get oil to the lifters.

Here's a picture of the '65-'66 BB rear cam bearing with the 3 holes (thanks to Joe Lucia's post in the archives).


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