In 1999 I bought an engine rebuild kit from Summit. The kit included an M55hv oil pump.

After 15 years in stasis, I am ready to build this short block. The bottom end is within stock specs for the rods and mains. I used Comps lifter bore groove tool and have Crower cam saver lifters in an effort to get more oil to the flat tappet cam.

Question is about the oil pump that came with the kit. Its the original design Melling M55HV before they made changes to the castings that caused them some problems.

I probably don't need an HV pump but I have it with its tack welded screen and steel sleeved rod. I won't be racing or spinning past 5k and will be using a stock pan with 10w30 Zrod oil.

Would you get another std. vol. std. pres. M55 type replacement pump OR go with what is in hand?

The pump bypass spring is pinkish and is said to be 70psi.

Thanks for looking and any advice. I have thought myself in a corner on this.

 

It sounds good to me.

 

Get a std M55 and install the #60 pound spring.

 

I would use the HV. With the lifter bores grooved and the EDM hole cam saver lifters you have 32 spots that are leaking internal oil pressure. A stock pump may not deliver the volume and pressure you need with that many spots draining pressure internally. There is a procedure you can do to deliver a direct stream of oil on the distributor gear also. I would do it because of the loading a high volume pump puts on the gear.

This is from Crane.

When a high volume oil pump is used in an engine with stock internal clearances, the increased volume of oil can't flow through the engine fast enough to relieve the back pressure created. This places an increased load on the distributor gear, and leads to accelerated wear.

Once the gear on either an 8620 steel cam or a cast iron cam is worn excessively, the cam itself must be scrapped! There is no repair for this problem, and the only option is to buy a new cam. To eliminate this annoying and expensive problem, we offer a simple, do-it-yourself way to help oil the distributor gear and reduce this accelerated wear in Chevy V-8 and 90? V-6 engines.

On these engines, the lower portion of the distributor housing drops through the oil gallery that supplies oil to the lifters on the passenger side of the engine. Two rings at the bottom of the distributor housing seal the top and bottom of this galley. Oil flows around the distributor, between the two rings.

Solving distributor gear wear is as simple as filing or machining a .030" groove in the bottom ring of the distributor housing. A three cornered file can also be used.

The distributor housing should be grooved in any engine operated for extended periods at low engine RPM. With the distributor installed in the engine - ready to run - the groove should face TOWARDS THE CAMSHAFT. This will provide a reasonable flow of oil to lubricate and cool the distributor gear and cam gear as they operate.

 

Ive always heard a HV pump with stock pan can cause oil starved situations at higher rpm, any truth to this?

 

Yes, but not with 32 points draining oil pressure and volume below the lifter valley. Adjust with a 5W-30 or 0W-40 high ZDDP synthetic for quicker drainback, better protection, less bypass. I would rather make sure I maintain enough oil volume and pressure with these internal mods than get it together and not have enough with a stock pump. A melling high volume is only 25% higher than stock. He will lose that or the majority of it below the valley directly on the lifters and cam.

 

so an engine with out his mods that never sees over 6k should be ok with stock pump and pan right?

 

Did this to mine (note hole in bottom of body)
I know, wrong type of washer.

Fwiw I have a 99-00 era M55hv spin it up to 7k so far so good.

 

Yes. Stock is the way to go on the majority of street builds. His mods require more volume. It is similar to wide bearing clearances in a race engine requiring more volume due to internal leakage. Sometimes a high volume pump and thicker oil is needed to maintain adequate flow and pressure if clearances are wide.

 

Nice!

 

In 2013, I pulled my M55HV at the recommendation of Comp Cams when I installed my Retro Roller cam kit. I could have saved myself the trouble... the 'stock volume' M55 pump (Mellings) I installed performs about the same as my M55HV. Perhaps it is due to age of the 'HV' pump (weak spring?) but the oil pressure is comparable.

Also, there may be a difference between high volume and high pressure.

I'd say run the M55HV and enjoy the higher volume.

Oh, and my kit with the HV pump (from Northern Auto Parts) was from 1999. The pump had no issues whatsoever. I would install it again as I have saved it just in case I need it someday.

 

Thank you everyone, this is great info.

I am thinking I will install the m55hv, time and break in the engine and see what the pressure is looking like. I love the oil groove idea and the oiling hole.

Am I right to think with the groove , I would need to time it first and make a mark up top to make sure the groove is in the right place pointing toward the cam?

But, the hole idea the placement would not be as critical because it is dumping oil right on the gear? I would love to hear more about how you drilled that hole. Did you free hand it? Did you start at the bottom or at the top?

Thanks again.