I have been caught between the rock and a hard spot with the need for a M55HV and the M55. Well my first intention was to installed the standard pump, then I read wher a motor making over 400hp would need a M55HV. So I went out and bought the M55HV and welded the pickup to it. Now I see people using the HV with the extreme pressure and ruining gear drives. I have finish installing my pan and now i'm thinking about switching back to the M55 Standard Pump while it's still on the engine stand. Whats you Opinion M55HV or M55?
Here my clearances:

Main Bearing Clearance 0.002
Rod Bearing Clearance 0.0015
Crank End Play 0.005
Main Cap Torque 65
Rod Bolt Torque 63
Rod Side Clearance 0.0220
Piston-to-Bore 0.005
Top Ring End Gap 0.016
Second Ring End Gap 0.014

With the clearences you have I think the M55 will work fine.

I forgot to say that i'm using a Milodon Diamond Stripper Windage Screen, Crank Scraper, and Lifter Valley Baffle. Will they item require the use of the M55HV. If not it's time to drop the pan and change the pump Again :(

You dont need an HV pump, im taking mine out because, it has great oil pressure from idle and around town but as soon as i hammer on it it partially sucks the pan dry and oil pressure drops on top end. Im going with the M55A. Z-28 "high pressure standard volume" Pump. Thats my recommendation.

I guess I need to take the oil pan off and swap it out. Thanks
Dave

A HV pump does NOT suck the pan dry..Wife's tale..show me a documented case in a street car.

i ran a melling hv pump on my 406 stroker daily driver for 3 years and on my 350 daily driver for 2 years with no problems.

Originally posted by mr 4 speed:
A HV pump does NOT suck the pan dry..Wife's tale..show me a documented case in a street car. Obviously, I wasn't "IN" the pan when it happened but a guy I used to hang with had the HV pump and his oil pressure would drop to ZERO on the highway. 4.11 gears and up around 75-80 the needle on the guage would just drop. Slow up and it would come back up.
I had one in my Camaro with no problems but with only 3.08's I never realy turned the motor very hard.

Jeff

I am running a speed pro HV/HP pump on my 502 and never have had a problem.

i have a HV and around 5k my poil pressure will go from 70 to about 40

Originally posted by 300hp:
i have a HV and around 5k my poil pressure will go from 70 to about 40 40 psi at higher speeds, or when the engine warms up ?

If the oil pump pickup is too close to the pan, you will likely have oil pressure problems at higher rpms. If you install a high volume pump ( which will be longer than a stock one ) and run the same stock oil pan, you may very well have too little clearance.

I had one and ended up taking it out. Here is a link, and yes, I did verify that I had 3/8" clearance between the pickup and pan.

http://www.chevelles.com/forum/ultimatebb.php?ubb=get_topic;f=9;t=010742#000000

Here is the verification of the repair:

http://www.chevelles.com/forum/ultimatebb.php?ubb=get_topic;f=9;t=012800#000000

Mike

I agree with mr 4 speed completely. If you have issues with a HV pump it is because you have issues in your oiling system with drainback.

From what I have gather,people experience problems with the HV because their "Oil System" is not set up properly. Just installing a HV pump without proper components to ensure the sytems is set up complete. With that being said I think if you set your system with a good Milodon Windage Screen, Crank Scrapers, Deep Sump Oil Pan 7Qts, Proper Clearances (oil Pan/Bearings) and the HV oil pumps everything will be fine.
Correct me if im wrong.

From the link provided earlier states that distributor gears are NOT ruined by the HV oil Pump by itself, its getting the blame for the failure:

I can say that I rarely ever use a HV pump, made the decision to use one based on the Crower HIPPO lifters I'm using bleeding oil constantly..
It cost me a distrbutor gear and cam...

I don't care what the Melling propaganda says, I've NEVER lost a distributor gear, the gear was centered on the cam, the cam was new with presses on iron gear, the gear was in good shape, and had been run previously for 2 years without any unusual wear, etc..

Motor had perfect bearing clearances, initialy was to have a 7 qt pan but wouldn't fit the chassis, has a windage and crank scraper.

I've built probably somewhere in the neighborhood of 1000 engines, and repaired may more than that..

This combo had too much pressure. Pressure is created by volume and restriction of as the article mentions.
Too much volume=too much pressure.
I had almost 100 psi cold pressure with 10-30 oil.
WAY too much. Over 75 psi warm idling with a few miles on the motor. It never got over 100 miles...

Had I had a stock oil pump it would have been fine... And cost me one less headache and saved me a few hundred dollars.

My input based on actual experience and not some marketing propaganda..

Deeboo, use the M55 if it's on the motor now. HV pumps are teats -on-a bull-hog AND can actually cause problems. Using remote filters or supplying a turbo. Those are HV apps.

IMHO, the higher you swing the motor, the more of a LIABILITY the HV pump is. For a mild 5000 rpm motor, the HV should be fine, albeit a complete waste of energy.