OIL MODS

Wyrmrider said

we used to groove the block side of the mains and feed from the side plenty of clearance there to form a good wedge
6 o'clock is a tough place to get oil in due to the pressure being down- or moving from side to side depending on which side is firing
half grooved mains you loose a lot of support with full grooved mains

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We tried all that. I don't know why the knowledge isn't more common. It's settled science. The rods need full pressure, full flow at ~ 70 degrees past TDC. You can't get that with a groove. The hole in the block has to line up with the hole in the main bearing to feed the rod.

The higher the RPM, the more critical it becomes. I first came across this with a T/A block W-2 engine I bought complete in 1984. The guy who sold it to me paid a hydraulics engineer to fix it. He made me promise to never change it. I tuned it 8500 and never hurt a bearing. Broke some valve springs so I decided to freshen it up. Everyone and their mother (none of which knew jack **** about hydraulics) convinced me to change it. It took another hydraulics engineer and a bunch of broken parts to put it back to correct.