Oil bypass shimming

[mainline331]

Hello
I often see references to shimming the oil bypass spring for more pressure/ volume. Can someone explain how to do this, and how exactly it works? Are there any guidelines for how much/ what type of shim to use? I am looking to increase the pressure on a flat 6.
Thanks
James

 

[bubba22349]

Shimming the by pass spring will increase the pressure but not the volume. It is as simple as putting a washer in to raise the springs pressure keeping the reg. from opening as soon = raised oil pressure. Depends how much higher you want to go you might start with .040 - .060 and see if that’s enough on your oil pressure gauge I would use a good aftermarket type for the readings before and after. Back in the day a full. race Flathead V8 would run about 80 psi. Are you running grooved main bearings or a cross-drilled crank in your six? On the higher volume part you would need to install taller gears in the pump body

 

[mainline331]

Hello
I had planned on crossdrilling the crank on an upcoming motor, but was unsure of grooving the crank. Any ideas on this?
My current two motors have the stock crank configuration.

 

[bubba22349]

The old racers turned a 1/8” (.125) radius grove that was centered or lined up with the main bearing grooves.

 

[flatford6]

The oil pressure relief valve is located on the distributor side of the block just ahead of the bell housing mounting surface. It can be unscrewed and the spring and plunger or ball accessed from there. For hot rod street use, stock pressure is enough as is the stock flow volume. A full flow screw on filter would be a nice improvement and volume to the bearings would increase because the stock bypass filter dumps the small percentage of the oil that is filtered back into the crank case instead of the oil line main gallery. The principle of the thing is the same as the flathead Ford V8 except no external oil lines. I think the main restriction of the system is on the inlet side between where the inlet pipe bolts to the block and makes a sharp turn (sharper than 90 degrees) and where the oil pump bolts to the outside of the block. Some grinding on the short radius of that turn could probably help flow.

PS for Mainline331: I left you two phone answering machine messages.

PS for Bubba22349: I left you a PM about a 262. If interested please send a PM.