Midnight 85

Slalom4me, here's the pics you requested,,

Slalom4me

Can you speak a bit about why you describe the M155HV as the weak casting?
When I look at the width of the shoulder created by the spot facing for the
attachment bolt, it looks wide - signalling the heavy casting.



Here are some images I received about differences between the Melling
pumps. The pump in your picture resembles the one on the right.



However, now I wonder if there are three levels of castings: weak,
intermediate and heavy. The M-Select 10553 on the right below looks
to be a heavier casting than the M155HV above on the right. See how
much wider the notch created by the spot facing is? The wall thickness
of the boss looks thicker, too.



.

85vet

When I saw the pics I thought the same thing. Looks like multiple changes depending on pump #.

Seems to be a never ending saga for sure.

Midnight 85

As you know, your last pic is what the old castings looked like, plenty of material in the mounting area. I'm not even going to attempt a guess as to what Melling is doing. The pic of yours that shows the cracks in the mounting area is the same thickness as my 155 pump but my pump doesn't have the sleeve through it. Once I saw the yellow disclaimer in the box, that was enough for me to forget about using it. I used to race a 57 Chevy about 30+ years ago and then I switched to a 350 powered Vega and in EVERY rebuild I did on those engines I used nothing but the M55HV pump with not one failure. None of these pumps had any type of disclaimer in the box either. If I ever need another small block Chevy pump it's going to be a Milodon.

Slalom4me

I stopped by a local shop today and discussed this with the mgr.
He brought out an M55, M55HV and an M-Select 10555 for us to
look at. (These do not have equivalent dimensions, they happened
to be what he had available in the three models.)

The M55 clearly has the least material in the pump leg, the notch
created when the bolt hole was spot-faced was <= 3/16" wide.
The top of the leg where it joins the main cap is surfaced flat with
no pocket. The casting is light/medium gray in colour.

The M55HV is the same colour but the notch is wider. The top of
the leg has a pocket. The picture Midnight 85 posted above is
pretty much the same as the pump I looked at. The same warning
card is in the box.

The M-Select 10555 comes in different, black packaging. The casting
colour is much darker. The notch is wider than the M55HV. The
casting seemed beefier in the main body, too, with more rounded
corners and less casting flash. The top of the leg has a pocket.

.

Slalom4me

Any updates from other thread participants or interested parties?

My Melling M-Select #10553 (SP, SV, 5/8" inlet) arrived Thurs.

Unfortunately, the sealed box had opened enroute and the std spring
is AWOL. The pumps are assembled with the pink high pressure sprg
and they enclose a black standard spring for you to install if desired.
The vendor is going to request a replacement.

A driveshaft with a pinned steel collar is also included.

I have yet to compare this pump to the OEM L98 pump to verify
dimensions and inlet suitability for my pickup & pan. It does feel
heavy but perhaps I just haven't held a pump for a while.

.

85vet

I did finally install the M10552 after having a pickup fabricated by kevco. Corkvette1 changed all my bearings out and I just finished installing new hooker comp. headers so I am hoping to fire it up tomorrow.
The 10553 you mention is beefier than the original but the dimensions are the same. You should be able to use your pickup.
The only recomendation I have is to use a stud for the oil pump and toss the bolt.

Slalom4me

How did the bulkier M10552 fit, any clearance issues?


Preemptive measure? Or did you find problems? What bearings
were chosen as replacements?

We looked at mine when I changed the pan last spring and (chuckle)
switched to a Moroso 22100 that has turned out to be based on the
weak version of the Melling. I had been worried that inadequate
oil control with a previous RR pan under heavy braking might have led
to bearing issues - but inspection then showed the bearings to be in
good shape.

.

85vet

Maintenance items - we replace bearings every other year, plus I did have some low oil pressure at idle issues that the new pump should take care of.
I used clevitte coated H-series bearings for mains and federal mogul coated bearings for the rods. I had the mogels so I used them.

The pump itself fit fine, I just had to have a new pickup fabricated. Do to the weight of the pump I did change to a stud. The stud has a washer with the nut and should distributes the weight better than the bolt.

Just a note - we run redline 0-20racing oil at all times and this is the main reason I went with the 10% increased pressure.

Steve85

I wishI would have read through to the end to save myself some trouble. Canton #21-500 SV, SP pressure balanced pump is the new weak casting. This blows me away that Canton is using a "non-performance" pump for their advertised...

Believe me, I know Canton is caught in the middle, and the gentleman I spoke to was quick to issue a return authorization, but it bugs me they are just re-selling this thing as good for high rpm race motors. I guess I hoped they would be using old style castings.

Anywho, I need to review this thread for the proper part #. I believe the 10553..

maybe this is a question for the builder but..What is the general criteria for hi pressure hi volume, versus std for an application?

My application is a Canton road race pan 7" depth. I too will post my findings for fitment.

This thread is long and gets into a few different applications and is one of the most valuable on this forum. I big shout out to the creators, editors, and workhorses.

Slalom4me

Sounds similar to the Moroso 22100 in my car.

The M-Select 10553 5/8" inlet, standard pressure, standard volume pump
is the model I've chosen for use with my 7" Armando's RR pan.

I previously used a 15-240T Canton pan and I feel that as far as pump
fitment is concerned, the Armando and the Canton have similar requirements.
The 10553 comes with a HP spring installed and a SP loose in the box - my SP
was missing so I can't say more about fitment at this time. I feel
comfortable with 85vet's assessment that success is probable and I am
going to follow his recommendation about mounting the pump with a stud.

At the risk of provoking a samaritan to respond, I urge a new dedicated
thread for the pump Volume/Pressure question. That will bring in knowledgable
folks who might not see/contribute here and help keep this thread from
becoming any more unwieldy.

.

85vet

Slalom4me,
Fired up the beast, but with cold weather and expensive 100 octane gas in tank I did not let it completely warm up. My oil pressure cold with cheap 10-30dino oil to clean out bearing coatings was 50 to 55 psi.
I am expecting it to go to about 30psi hot with 0-20 redline racing oil.

Also, personal thanks on keeping this thread updated and helping out the forum members.
Jim

scorp508

Hmm... I've had an M55a pump in my car for about 23k miles. Most of those have been highway miles, but it makes me want to pull it and take a look.

_twisted_

You might have installed prior to the casting change

scorp508

That would have been the (thinks hard) 2002-2003 time frame when I put it in.

85vet

You are in good shape
Change took place 2005 and hit the market late 05 early 06 due to large inventories at retail locations.

scorp508

Great, thanks!

conv90

I ended using the M select 10554 (same as the 10553 but with the 3/ pickup..).
Pete said that the pump seems the same as an old m55 pump.

ZBRA

I have an M155HV. It was ordered from Thunder Racing, it was manufactured in April of 2006, and it is made in the USA. It uses the casting on the right side of the picture above.

Included in the box is a note that states:

Anyone found any M Select pumps yet?

Slalom4me

Duntov just put in a 10554 Help. '95 Showing little to no oil pressure
It seems to display pressure readins that suggest it has a high pressure
spring.

dmaaero elected to get a 10552 oil pump

I have a 10553, but it has a pink spring which I believe is the
high pressure item. I am waiting for a standard pressure spring
before installing this pump.

I believe Pete K. installed the 10554 conv90 mentions in a post
above just above.

Are you having difficulty locating an M-Select?

.