Oil Restricters

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slkalo
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Years Owned: 1967 Toronado deluxe

Oil Restricters

Postby slkalo » Wed May 18, 2022 8:46 pm

I am rebuilding my '67 425 and wonder about the use of main bearing oil restricters. Anyone have personal experience as it seems to be a universal thing in the olds engines. I'm not sure restricting oil flow anywhere in an engine is a good idea.

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Otto Skorzeny
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Years Owned: 1966 Toronado

Re: Oil Restricters

Postby Otto Skorzeny » Fri May 20, 2022 5:29 am

Rebuild it to factory specs with the best American-made parts you can buy and you'll get another 200,000 miles out of it. The original designers of the 425 knew what they were doing.

Willysnut1959
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Re: Oil Restricters

Postby Willysnut1959 » Fri May 20, 2022 1:25 pm

I installed Mondello's oil restrictors in a 455 that I built for my 1972 442. I understand that in Olds engines, more than sufficient oil is fed to the lifters while the front main bearing may not receive sufficient lubrication in extreme conditions. These restrictors force more of the oil and pressure to the main and rod bearings and less to the lifters. The only negative issue with these restrictors is that the oil pressure sensor is in the top of the engine and will indicate low oil pressure when the engine is at idle.
Marty

bcroe
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Re: Oil Restricters

Postby bcroe » Sat May 21, 2022 12:23 pm

I put in a high volume oil pump with stronger hex shaft. This is
not to get more pressure, but I feel it better maintains pressure
esp with some wear at idle. Good results in small blocks for
decades. Bruce Roe

slkalo
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Years Owned: 1967 Toronado deluxe

Re: Oil Restricters

Postby slkalo » Mon May 23, 2022 6:43 pm

I went ahead and followed my Dads sage advice that you don't restrict the flow of oil to bearings. We posses an original manual from "back in the day" and the oil goes from the passenger side main oil galley down to the mains, then up to the cam bearings. The cam bearing lube oil just rains back into the pan. We did what you did Bruce, high volume pump, factory passages. The only slowing of flow we used was reduced flow hardened pushrods to minimize oil pooling in the heads, as every olds V8 I've seen is very very adequately oiled in the top end.

Schurkey
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Re: Oil Restricters

Postby Schurkey » Fri May 27, 2022 12:45 am

Willysnut1959 wrote:I installed Mondello's oil restrictors in a 455 that I built for my 1972 442. I understand that in Olds engines, more than sufficient oil is fed to the lifters while the front main bearing may not receive sufficient lubrication in extreme conditions. These restrictors force more of the oil and pressure to the main and rod bearings and less to the lifters. The only negative issue with these restrictors is that the oil pressure sensor is in the top of the engine and will indicate low oil pressure when the engine is at idle.

NO.

The front main bearing is fed by the oil gallery BEFORE the lifters on one side of the block. That's why the main saddle for the front bearing is triple-drilled--One drilling to get oil down from the lifter bank on one side, one drilling to get oil up to the lifter bank on the other side, and one drilling to get oil to the front cam bearing.
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Olds_Plugs_01.JPG (82.38 KiB) Viewed 7551 times


The "Mondello" oil restrictors do not directly change the amount of oil going to the lifters. They do not directly change the indicated oil pressure at the oil pressure sending unit port.

They restrict oil going to the CAM BEARINGS, not the lifters. And you can do the same thing by drilling smaller holes in the cam bearings, then installing the cam bearings so the smaller holes line up with the oil gallery instead of the larger holes.

Which is all academic, since oil flow across the bearing is metered by the cam journal-to-bearing clearance, moreso than the oil flow into the bearing.

In short, the Mondello oil restrictors are a way for Lynn to pull money out of people's pockets while providing no real benefit. Typical of that business.


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