I ordered several more parts today. And, I decided to get a new oil pump (for the production block I'm reusing). Melling brand is what they carried.

They offered 3 choices for replacement: standard, hi-flow, and hi-pressure. I ordered the hi-pressure (which is supposed to flow approx 30% more than stock).

Because the order won't ship until tomorrow morning, I have to opportunity to change the order to a standard kit (if anyone thinks that's a bad idea). I'm aware that a hi-flow pump could be a bad idea w/o a bigger pan (if oil supply is insufficient). But, the performance shop where I ordered, thought oil supply wouldn't be an issue using the hi-pressure model.

Agree or not?

Gregg

(FWIW: All 3 models were the same price.)

 

BTW: The other consideration I forgot to mention is my intention to reuse 55k mile production shortblock. Any reason higher oil pressure would create oil burning or other issues in combo with a used block?

 

Youll get 1000 different answers here, being as yours wont rev to the moon you can use about anything and it will last fine. Use a hardeend shaft for cheap insurance.

 

I use a high-pressure, its fine.

 

The stock or high pressure will be fine.

That being said,Read this link,for more info.Theres some good answers on that first page.

http://www.hotrodders.com/forum/high...utor-5521.html

 

Thanks for the link! I'm not sure if the answers are good, bad, or inconclusive.

One thing that seems apparent is the potential for problem is less -- if I avoid using a HP/HV pump for my application. And, RPMs will stay around stock redline recommendations after my build.

The Melling quote (in the link) said the use of a high volume pump could not cause premature wear but then implied that higher pressure pumps could cause extra wear. (That's because the creation of higher pressure exerts more pressure on the gear(s)).

So, I'm leaning back to a standard pump.

Though I haven't asked yet, does it matter if I was planning on reusing my stock 55k mile HEI distributor? And, what gear material is best for the cam gear? I was planning on cast iron (to match stock) but saw an 08 prefix for comp xfi cams is supposed to have bronze. 12 prefix says steel. TPIS told me they pressed cast iron onto their cams to prevent wear from different materials. Which (cam) gear material is best for a used HEI dist?

 

Resue your distributor, get a cast gear on the cam.

 

HV pump here, no known issues for 3 years. performance shops love to use HV pumps, the average customer gets all happy when he sees the psi up around 60-70 on the highway.

 

HV is fine in my application, but there were issues with the regular melling pumps. There are no issues witht the 'select version', worth the extra $$ in MO.

 

I Agree 100% with mseven.
the "M select" is the one you need to buy.
-Beppe-

 

Gregg don't forget for the "high volume" pumps it is recommended that you also upgrade the pump shaft to one that doesn't use the plastic clip...example:http://www.summitracing.com/parts/ARP-134-7901/

 

I run the "M" Selct high volume pump from Melling but I also run a 7 qt. oil pan so sucking the pan dry is not an issue. I have never seen a properly built small block that needed the high pressure pump, so with those two things in mind I would suggest the standard "M" Select pump for you with the appropriate pickup and the hardened shaft with the steel collar.

 

HV and HP were designed for people whom are pushing the crankshaft bearing tolerances on the "loose" side. I cringe when i see people with cold oil pressure in excess of 80psi. I think about all the oil being sucked out of the pan. Do you have any idea of your main and rod bearing clearences, yet? Would be useful information on making the correct choice.

But you could use all 3 variations, however, I think you would be fine with a standard "select" series, Melling pump, If all clearences are with OEM specifications.

 

• What camshaft will be installed?
• Which model & P/N of Melling pump is on order?

My vote is that distributor gear selection has to take into
account the companion gear on the camshaft. For an OEM roller
cam, my vote is that the OEM GM Melonized gear is preferred.
The large and small cap distributors have different shaft diameters
- order the appropriate gear.

As mentioned by mseven & conv90, there were problems
associated with a redesign of the casting for the traditional
Melling pumps. In short, cracks developed in the mounting leg
with a result that some pump bodies separated and ceased
pumping.

Several threads appeared regarding the issue at that time.
The then-recently released Melling "M-Select" pump series has
a much heavier casting - it is available in several pressure,
volume and inlet tube diameter configurations. Links to the
Melling "Select" catalog appeared in posts in the threads along
with discussion about the different P/N's.

I do not know of any subsequent follow-up to determine whether
Melling has made subsequent revisions to address the apparent
short-comings of the casting redesign of the non-M-Select
pumps.

Incidently, several people found that Melling pumps which were
sold as std pressure configurations were delivered with high
pressure springs. There were threads discussing the wire diameter,
coil count and uncompressed length of Melling Bypass springs.
There are two spring designs (possibly others) - pumps where the
spring is retained with a pin differ from those retained by a threaded
plug.

Some general considerations regarding pressure & volume.

If no changes in configuration or operation are planned,
then my vote is to remain with a pump that provides stock
pressure and volume.

Reasons to increase pumping pressure include addition of
components that cause pressure drops, reducing the net
pressure at the bearings. External filters &/or oil coolers
along with the fittings required to plumb these are examples.

Reasons to upsize pumping volume include changes that
increase the size or number of points where flow can
exit the oil gallery. Increased bearing clearances is
one example. Addition of a super/turbo charger lubricated
with engine oil is another.

Higher pressure requires more work. This work elevates
loads on the pump body & drive mechanisms (shaft, gears
camchain.) It reduces the output energy available at the
flywheel.

Surplus pump volume may increase oil temperatures. The
surplus oil is diverted through a bypass valve back to
the inlet side of the pump. Pumping work heats the oil,
if oil makes multiple passes through a pumping chamber
before continuing into the galleries, the oil becomes
hotter than it otherwise would become.

An SAE paper reported that while testing at 2,000 and 4,000
RPM WOT the oil pump contributed 8% of total heat energy
imparted to the engine oil.
.

 

Well, I did have an M55A ordered. But, I dropped that item from my order after reading the replies/links provided here. It does sound like the M55 series is a risky venture now.

Guess I'll pick the 10553 -- once I figure out what pickup, drive shaft, etc... I need to go with it.

Cam options:
I've considered either a 12-465-08, 12-465-08, or custom in-between (with 214/218 duration). Those are comp xfi cams with .570" lift. Alternatives include a custom Bullet or TPIS cam (with 214/218 duration and milder ramps... probably .525ish).

 

Ended up picking the 10552 (10%HV) pump from TPIS. Clay recommended it (along with a Cloyes true roller chain).

Thanks for getting me the info necessary to switch to the higher quality "Select" units.



Cam, rockers, lifters, and clutch are about all I have left to buy. (Probably an all-alum radiator too.)

 

Did the 10552 pump fit with your OEM oil pan? Mine didn't!

 

Gregg, I'm running a 383 with a HP oil pump, the initial start-up pressure is very consistant around 70-80 psi which may be a little more than I would like, normal running pressure is great I have zero issues with it. I also have a DUI HEI dist with a cast gear, I initially had a broze gear which lasted less than 100 miles.