[SY1]

Robert you want to use the Melling Select line of pumps. There are six to choose from, 2 std volume, 10553, 10554; one 10% high volume, 10552; three 25% volume, 10550, 10551, 10555. The 10553 replaced the old M55A Z28 high press, std volume pump. I'd look hard at the 10552, really don't need 25% volume increase, the 10% is a small step up and I'd put the Z/28 spring in it if it doesn't already have one, just to get the pressure up a bit.

The select series have steel gears, not cast gears, most have pinned drive gears, some have bolt on screen provisions, and shaft supports. There are also three race only pumps for the sbc, 10552C 10% high volume and 10555C and 10990C 25% high volume, these have the anti-cavitation grooves and 3/4" inlets. Pumps 10554, 10552, 10551, 10555 have 3/4" inlets and 10553, 10550 have 5/8" inlets. Pumps 10552 and 10555 have bolt on screen provisions and shaft supports. Pumps 10553, 10554, 10550, 10551 all have pinned drive gears.

Melling tech support sent me this:

"This pump was redesigned for GM at there request.
This pump matches the pump they use in there production engines and sell in there service line.
In the early 90s Melling started producing performance pumps known today as our Melling Select Line.
These pumps are of the old design with other positive features.
We have for some time included caution sheets in the new design pumps stating that they are not recommended for performance use.
Yes we still build the best small block pump on the market.
The 10553 pump replaces the M-55A"
Thank you
George.

It was a really dumb move on their part to continue to use the heavy duty pump part numbers on the lighter duty, not fit for high perf use pumps. Anyway the select line is what you need.

Take a look at this item from ebay and notice the chart at the bottom of the ad. It should make selecting your pump easier.

http://cgi.ebay.com/ebaymotors/SBC-...063QQitemZ110017864315QQrdZ1QQsspagenameZWD1V

One of the give aways to identifying a light duty new style pump is the outlet from what I've seen is milled flat and not recessed. Also you'll see two ribs usually running up the side of the outlet to try to strengthen them. I've seen the weaker duty pump without this though, just look at the outlet end for the recessed mating surface.
Dave

 

[SY1]

Robert there is a 22112 for sale on ebay right now. It's never been installed. I can't tell by the pictures if it's the heavy casting for sure, but it appears to be. Looks like the blueprint series pump uses a unique quad square drive shaft that moroso shows in their catalog using a nylon locking ring to hold it in place. I don't have any experience with Moroso's blueprint series, perhaps someone else using it will jump in and explain if it really uses a nylon locking ring to hold the square drive in the pump shaft.

I've done some more homework and I'll be going with the 10552 select myself. I like the 10% increase rather than a 25%. I'll also use the Z28 spring to pump the pressure up a bit in the 377.

 

[SY1]

Don that's a good question. Chevrolet lists the Z/28 pump spring as 70psi. I've seen various publications claiming 65-70, but Smokey claimed the Z/28 pump put out 9 gpm @ 70 psi @ 7000 rpm. I'm also reading various pubs from different engine builders and most seem to agree you don't want to go much above 70 and some say you're okay for street use with as little as 45. Smokey said 50 is the minimum you want for performance use, but performance use is a vague term. The non-Z spring will maintain 50-60 psi from what I'm reading. So it should raise the oil pressure10-20 psi with the Z spring. I wish I had a better answer.

You're right bearing clearances can make all the difference and assuming we are staying near the recomended .002-.003 on the mains and .002-.0025 on the rods the above numbers should be close at 70 psi for the Z white striped spring part number 3848911. Unfortunately it's probably trail and error. If I knew my pump would run at 60 without the Z spring I'd be happy, but at 50 on a new motor I might want to consider the Z spring.

 

[SY1]

Robert the high pressure spring is not included in the 10552 pump. It does come with the 10553 standard volume select series pump. But that pump doesn't have provisions for a bolt on pickup. That isn't a big deal if you can braze just remove the spring from the pump body and braze the pickup on in the correct location after test fitting it to your pan. If you don't remove the spring before brazing the heat can weaken the spring.

Jegs lists the following pickups for this pump. 7" deep pan uses 689-12557, 7 1/2" pan uses 689-12558, 8 " pan uses 689-12559 they all run about $15.

Dave

 

[SY1]

Wildman yes you are correct. I'm not a hig volume pump advocate, just the opposite. I believe if you aren't using a remote filter and cooler and your clearances are correct there is no need to run a high volume pump. If you are using roller rockers and/or edge orifice solid rockers there is really no need to ever use a high volume. But that's just my opinion.

I would run the 10553 standard volume except the 10552 has a couple of features that I really like. First is the shaft supports for both gears in the pump lower cover and second is it has provisions for a bolt on pickup. I've brazed mine in the past, but the bolt on is really simple and there's no guess work or fitting involved when dealing with aftermarket pans. I have an 8" deep Moroso pan and know that if I use bolt on pick-up 689-12559 with the 10552 it'll be right where I want it to be. Of course I'll check it before bolting the pan on the final time.

I can live with the 10% increase, I certainly won't need it as the motor will never be in the car long enough for the bearing clearances to ever become an issue. But if I decide or need to add a cooler down the road it won't hurt to have the extra flow capability. I'm not using roller rockers and will use GM #5232695 piddle design flat tappets so those will allow for 20% more oil to the heads than the edge orifice flat tappet #5231585 GM recommends for roller rocker installations. I want to keep plenty of oil on the stamped 1.6 rockers and my covers are fabbed aluminum so they don't have the benefit of the drippers that the GM covers have. Also I think the additonal oil to the heads will help keep the valve springs cool since they'll be almost at their design limit for the lift camshaft I'm running (.040" from max rating). I'm also running a .030 hole in the main galley plug behind the cam gear to help keep the gear lubed since that line directly feeds the front main journal and the first 2 rods I don't want to have any issues there either.

The standard pump may work fine for all this, but in the end the 10553 pump doesn't have the other features I want, nor did the other standard select pump 10554, so I had to move up to the 10% HV pump of 10552. All the other select series pumps were 25% HV and I considered the Moroso blueprint series, but I have concerns about the drive shaft that Moroso uses with these pumps and no one could answer why Moroso uses a nylon locking collar on a race series pump. Including Moroso who has never returned any emails and doesn't answer their tech support phone line. So the choice to go Mellings select, who do respond to customers, was easy for me.