Well i went back they had a box from dynagear, it has a melling sticker on it says M-55A, on the pump it has a tag attached to one of the bolts says DM-55A, we compaired the pumps you can defently see a differance in person. the only warning in this box was about distorting the rear main with a wrong bolt. I think my old pump was a danagear also, it was a DM-55 with a sleve in the bolt hole this new one has no sleve. No step between the boss and the leg either.

 

here"s a couple of pics of the pump i picked up today.

 

Thanks posting photos of the M55A, I believe Dynagear
just reboxes the Melling pump.

The M55A is a Std Volume/High Pressure pump. It has what
I refer to as the intermediate weight casting (as does the
M55HV high vol/std press pump).

These photos show the slightly increased thickness of the
casting lip at the mounting boss on the M55A.





Compared to the 55-60 psi generated by an OEM pump with
a std pressure spring, the M55A probably generates about
70 psi at 6000 RPM with its high pressure spring,

I follow the belief that 10 psi per 1000 rpm is adequate for
a SBC. Using more pressure than is necessary.

- decreases HP at the flywheel
- increases oil temperature
- affects ignition and valve timing

The high pressure spring in the M55A can be replaced with a
standard pressure spring if desired. The spring from your OEM
pump might work for this if the spring housing dimensions are
the same. Alternatively, a new std pres spring for perhaps $3-5
will also work. (I know the HP springs are easy to find, but
SP springs do not seem to be as readily available.)

Or the $32 M55A could be returned in exchange for the $62
M-Select 10553. For a bit more money, you get the std
spring, a HD pump drive (not included with the M55A) and
the heaviest of the three castings Melling appears to offer
for the SBC.

.

 

I bought this Melling HV pump at the local AdvanceAuto:

 

The width of the lip where the mounting boss has been spot-faced
is wider on your M55HV than on the M55A.



Some comments about HV pumps.

The higher volume of this pump may be suitable for your application.
The 4-bolt mains and the nice rotating assembly indicate this engine
is destined for some high RPM workouts. But on an application like
mine, the additional volume would just wind up being recirculated
through the by-pass valve when the relief spring opens at some RPM
where the pump capacity begins to exceed the capacity of the galleys
to bleed off volume.

This by-passed oil has been heated by pumping action. (An SAE
paper reported that 8% of oil heat observed in testing occured
because of pumping.) When the oil is routed into the by-pass circuit,
it is not returned to the sump where some of the heat can dissipate.
Instead it is directed to the inlet side of the pump for another pass
through the gears.

Another consideration is that the additional work done by HV pumps
increases the parasitic HP losses.

If RPM, bearing clearances, piston oilers, turbos or other aspects
of an engine increase the oil volume requirements, then a HV pump
is the way to meet the additional vol requirements and achieve the
10 psi/1000 rpm rule-of-thumb.

But on a stock engine, my vote is that a HV pump just increases oil
temp and reduces horsepower at the flywheel.

.

 

Well said,

 

http://www.titanspeed.com/content/pu...portwet01.html

 

I decided i might as well exchange the m55A and get a m-select 10552 looks like a much better pump from the link posted thanks guys

 

This pump has +10% greater volume and a 3/4" inlet (accepts both
bolt-on & press-fit). It is a nice pump but is not a stock replacement.

As mentioned the 10552C version with the anti-cavitation grooves
appealed to me but not enough for me to deal with changing the
pickup my custom pan requires or determine whether there is clearance
for the taller height of the pump.

Two thoughts.

If you decide to use a bolt-on pickup, be careful to check that the
bolts do not bottom prematurely. They should screw in far enough
that there is no possibility of leakage/looseness of the pickup.
Use thread locking compound and consider safety-wiring the pickup
bolts.

Check the colour of the pressure relief spring - it can be seen from
the side of the pump. If it is pink, then my vote is that it is the
high pressure spring and unless you need high pressure, I'd recommend
exchanging it for a standard pressure spring for the reasons mentioned
in a previous post.

My 10553 is supposed to be a std pres pump but was delivered with
the pink spring. Fellow CF member Duntov has just installed a 10554
(std pres/std vol, 3/4" press-in inlet) and reports.
Very high, IMO. Remember that prior to the LTx, the oil pump is
driven by gears on the camshaft and the distributor. Excess
pressure shortens gear llfe, increases heat, yadda, yadda, yadda.

.

 

so....the M10553 is physically identical but has a High Pressure pink spring?

Secondly, what pick up should/could be used with a 300 hp pan?

Thanks