Which oil pump for "loose" bearing clearances ?

[Drewster]

Looks like my main bearing clearances will be .0020-.0024. Using 3/4 groove FM107M-1s.
Will a ported front cover be enough or should I use a HV pump for a street/strip car?


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[mtocrs1]

If your specs are within the factory tolerances a ported front cover should be fine. If more oil pressure on the gauge helps you sleep easy at night go with a ported cover and HV pump.


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[we4Mateo]

Ported cover should be fine. Those specs aren't all that loose. A little looser than factory but with good pressure, you'll flow more oil this way. Plenty of people shoot for those main tolerances on a street/strip motor.

 

[earlbrown]

Avoid the HV pumps, they're a waste of HP and extra load on the timing set/ft cam bearing. You could get a set of gears a foot tall and they could still only flow what the 1/2" hole in the block will allow.

If the engine's not assembled yet, match port the bearings to the main bearings oil galley holes. That should keep you in oil for a while.

 

[Nick Micale]

We built many turbo engines with the bearing tolerances you stated.

If you would actually check the published Buick factory specs for a turbo V-6 you will find none?

All the V-6's from 110 HP and up are all grouped together? If you check the Buick Power Source listing for a turbo build you will see they are right on the mark of what you have.

Ever seen a used up rod bearing that was the same thickness as a sheet of paper?

I removed one yesterday like that as the owner heard a noise in the engine. Only one half was left in the rod, the other half was only pieces in the pan. A local production shop did the build.

In the many hundreds of engines we have built, never have had a rod bearing be trashed for being too loose? I have personally beat the hell out of a few pistons, but never took out a rod or main bearing.

Detonation will kill a rod bearing, so will the clearance being too tight.

 

[Drewster]

Glad to hear. Thanks for the replies


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