I have the High volume melling Z28 pump With the necked down shaft for the 406 IM building. But.. IM wondering if I should use the Standard volume one? What are the pro/cons of each? I dont plan on spinning this motor over 6,000 rpms.

Thanks,
Mike

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Black 90 IROC, L98, A4, 323 gear. SuperRamed 406 in the works!

 

i prefer the m55 standard pump. i weld a brace on the pick up and bolt it to the pump body. i also lap the cover a little ,thin bead of permatex ultracopper and red loctite on the bolts. the HV pump can drain your pan at higher RPMs, heat up and foam the oil. lot of others will swear by the HV pumps.

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-=ICON MOTORSPORTS=-

 

John Lingenfelter recommends a stock volume pump, with Chevy's white Z28 pressure relief spring. I would check the clearence between the gears and cover. should be about .0025 and .0033 inch.

 

I use the M55 std volume unit, and replace the spring with the Mr. Gasket spring. As ede suggested, lapping the end of the pump body, the cover, and the ends of the gears will make it run smoother and disturb the distributor less. Leave about .003-.005" of end clearance for the gears. I concur exactly with his description of the disadvantages of a HV pump; and there are no corresponding advantages for it. In a motor without extensive oil system modifications of the sort that increase oil flow (cross-drilled crank, grooved main & rod bearings, squirt holes in the rod ends, etc.) a stock pump will deliver all the oil the engine will ever need.

ede's suggestion for bracing the pickup is also a good idea though a bit labor-intensive IMHO for a street motor. An easier good way of locking the pickup in so it can't fall out is to simply drill the pump and pickup after they're assembled and adjusted to fit the pan, and put a roll pin through there.

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"So many Mustangs, so little time..."

 

Thanks guys..I think I will get the standard pump. I keep hearing the same reasons not to use the high volume one.

Mike

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Black 90 IROC, L98, A4, 323 gear. SuperRamed 406 in the works!

 

I would also recommend taking the gears out and wire brushing them on a bench grinder to remove the burrs so they don't break off and get pumped through the engine.

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We need Perry Mason