Both were Melling pumps. First one was a Melling m155HV. Part # from Thunder racing 156-M-155HV. The second was Melling Select SBC race pump Part number from Summit Racing MEL-10555. The only difference I could see was a different style bolt used on the cover, a bolt hole for the pick up tube and a special anti rust phosphorus coating to prevent rust( ). There were subtle differences between the 2 castings but what looked to be the "weak" areas of the pump were damn near identical. I'm just curious if the HV pumps are already beefed up. Still, the same note was in the m155hv box that suggested the use of a select pump when using solid mounts.

 

HV Melling stock pan for 4 years now no problems @ 6800rpm... Good Luck..

 

I also went with the standard volume pump but with the high pressure spring. This what GM did with the Z28 motors. I figure GM knows what they are doing and that is good enough for me. Also went with the "new" Melling casting with the thicker neck.

 

I recently swapped my standard Melling HV pump for one of their select HV pumps and the casting around the base of the pump was significantly heavier.

 

I'll post a few pics when I get back from Canada. Did you do this just recently or a while ago?

 

FWIW when I had to select my pump I shyed away from the stock pump casting because of the change in quality. I wound up going with a melling select which comes in a few types of HV ( I checked for a regular volume pump with a matching canton pickup for my pan with no luck)

The hardest part is getting the right pickup tube to go with your pan.(the higher the overdrive, the lower the pump comes down from block) In my case I wound up getting a 10% with a pickup tube that came into spec with my pan. (after several phone calls and checking with clay later)

Some have also stated that using a HV pump will put more stress on the plastic oil drive gear. I along with others have made a bracket to support the area that cracks on these. I wound up making mine out 1/4 flat bar, and using a longer bolt to make up for thickness. I am keeping my fingers crossed that I dont have any problems with it.

 

Perhaps the first one was an old vintage pump (even if it came in a new box)?

This pic shows the difference with the newer style on the right:

 

Got my new motor back today with all of the paperwork.
The HV Melling pump included a note stating specifically to use the other casting for performance applications.
Apparently, my engine builder doesn't read so well.
Or maybe, I'm misunderstanding the warning.



The motor is primed, assembled and ready to install.
I suppose this it probably my last chance to change it out if it's going to cause me issues.

 

First the Canton pan now this... I caught the pump before I put the pan on but didn't catch the pan till it was in car and full of oil

 

LOL, I caught the pan in time, but I didn't catch the pump until it was already primed.

 

How much hp is considered high perf and what do motor mounts have to do with the oil pump?

 

Since the newer Melling mounting area casting is not as robust as the old, vibrations transmitted to the engine from solid mounts can cause cracking. Better safe than sorry by getting the thicker casting.

Note that Melling did improve some pumping characteristics of the newer design (a good thing) at the request of GM, but they took a little meat off the mounting area. It would be fine for a stock engine. IMHO, anything that will see more severe duty would benefit from the Select series pump casting.

 

i have a m155 and poly mounts should i be worried.

 

Does anyone have the part # for this "stock replacement" Select series, standard volume, oil pump by Melling or is it the same # ? Also, if a Select series is used, will a pink (or any other color) spring be necessary ?

Thanks,

 

10554 Melling Select. How could it be the same number as the other one?
I think the Melling version of the high pressure spring is pink. Use it or the GM white spring.