Seems to be a lot of debate over what oil pump to use... Guys on board here seemed to think that a Melling M55A (Z28 high pressure style pump) is the best bet, with a standard M55 second. Guys at the machine shop swear that any high performance engine MUST HAVE an M55HV high volume pump (they mostly build race-only engines, or stock passenger car rebuilds).
The head counter guy at Jeg's who just sold his machine shop last year had a different opinion. His thoughts were for an engine under those rpm's, stick with what the GM engineers spec'd out, and get the Melling M55. At the time, he was incredibly helpful and sensible in many ways, so I bought an M55. He said all I'm going to do with high volume pumps is chew up the oil pump drive gears, and that it's best to stick with the oil pressure specs that GM recommends for those engines.

What should I do??? Get an M55A, or stick with this? I'll have a bit under 400 hp, and a little ways over 400 in torque (400 small block, maybe 440 ft-lbs MAX.). Car will never see over 6000 rpm I hope.

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'71 RS/SS project: full roller 406sbc / 9.76:1 w/ E-Tec Al. heads / 750 Competition AFB / big 4 whl discs, 1-5/16 VSE ft & 1" Rancho adj. rr sway bars / 4 speed 3.23 posi / 81 Z28 & dual snorkel vette Air Induction

plain jane stock pump with stock pick-up. GM spent alot of time developing this and it is a proven winner!!!Especially in the hp and rpm you are considering...

Chuck, you are sweating over nothing. The stock GM pump is perfectly fine for what you are doing.

I run a stock pump with the Z28 spring, and it has worked great. HV pumps waste power and are not neccessary esp. on a street engine. Joe Sherman uses a bone stock pressure/volume pumps with the stock spring and this is on a 600HP engines. I've got an old article on a 580HP 357ci street/strip engine he built-up, and again, he used a standard-pressure, standard-volume Moroso oil pump.

Hope that helps.

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'Silver Bullet' 1977 Z-28 413" SB
11.73 @ 115.10 on drag radials
Old Vortec combo:
12.15 @ 110.52

Stick with the pump you got and get a new machine shop.

Look at my engine. I run a stock pump, Z-28 spring, 0.002 bearing clearances, and I get 70 psi @2000 rpms cold and 55 psi @ 2500 rpms hot.

I go with the Joe Sherman rule- 40psi is all you need on a street motor.

I haven't ruined any of the few I've put together yet. http://www.nastyz28.com/ubb/smile.gif

hydraulic lifters--- standard volume/pressure
solid lifters--- standard volume/high pressure spring

worked for GM for alot of years. just my opinion.