Melling oil pump

[Timothy B.]

I wanted top share observations of the Melling M-55 oil pump off my 67. I think this pump is better than the GM part in that the Melling has idler pin oiling as shown the the top lid.

I have the pan off to repair a leak and have cleaned and sanded the oil pump surfaces so the end clearance is .001-.002. I purchased a NOS GM pump and spent lots of time flatening the surfaces because of sloppy workmanship. This M-55 is nice and flat with a nice thick casting FWIW.

In particular I wanted to share how they oil the idler pin, nice pump..

[Clem Z.]

Re: Melling oil pump

I wanted top share observations of the Melling M-55 oil pump off my 67. I think this pump is better than the GM part in that the Melling has idler pin oiling as shown the the top lid.

I have the pan off to repair a leak and have cleaned and sanded the oil pump surfaces so the end clearance is .001-.002. I purchased a NOS GM pump and spent lots of time flatening the surfaces because of sloppy workmanship. This M-55 is nice and flat with a nice thick casting FWIW.

In particular I wanted to share how they oil the idler pin, nice pump..

you can just drill a 1/16" diameter hole in the root of one tooth of the idler gear near the middle to oil the pin.

[Clem Z.]

Re: Melling oil pump

I wanted top share observations of the Melling M-55 oil pump off my 67. I think this pump is better than the GM part in that the Melling has idler pin oiling as shown the the top lid.

I have the pan off to repair a leak and have cleaned and sanded the oil pump surfaces so the end clearance is .001-.002. I purchased a NOS GM pump and spent lots of time flatening the surfaces because of sloppy workmanship. This M-55 is nice and flat with a nice thick casting FWIW.

In particular I wanted to share how they oil the idler pin, nice pump..

while you are at it you can radius the pump output passage above the gears. use some machinist bluing to make sure the rear main cap is not blocking any of the pump output passage

[Kenneth B.]

Re: Melling oil pump

I wanted top share observations of the Melling M-55 oil pump off my 67. I think this pump is better than the GM part in that the Melling has idler pin oiling as shown the the top lid.

I have the pan off to repair a leak and have cleaned and sanded the oil pump surfaces so the end clearance is .001-.002. I purchased a NOS GM pump and spent lots of time flatening the surfaces because of sloppy workmanship. This M-55 is nice and flat with a nice thick casting FWIW.

In particular I wanted to share how they oil the idler pin, nice pump..

TIM
My shop made most of the patterns for Melling Tool castings. They are in Jackson Mi. & most of the castings were made in Sturgis & Calhoon Mi. Harry Melling did a great job of improving on the originl ones for after market. It was reverse engineering if you get my drift. Take what's there & make it better. I still have the master pattern for the M-55
KEN

[John D.]

Re: Melling oil pump

Melling 55 is the worlds best oil pump for our some of our small blocks. Nice stock oil pump. Some insist on using a hi-pressure or hi-flow oil pump and end up with issues with FI distributors leaking and oil on the floor.

[Clem Z.]

Re: Melling oil pump

there was one melling SBC oil pump they had a problem with it breaking off the engine under rough conditions. if yours has a sharp edge on the main body where they machined the flat for the bolt i would radius the sharp edge just to be safe.

[Jack H.]

Re: Melling oil pump

there was one melling SBC oil pump they had a problem with it breaking off the engine under rough conditions. if yours has a sharp edge on the main body where they machined the flat for the bolt i would radius the sharp edge just to be safe.

I'm remembering this as well, and it involved a new, cheaper casting design. My recollection was that Melling (and several other mfgs) went to a new casting that was not as stout. I thought it included the Melling M55 model. The better setup was to get the M55A (Z28 pump) which still had the good ole casting, and then swap the higher pressure spring that was installed, with the std pressure spring that was also shipped in the box. Maybe Melling got smart and changed back to the old casting for the M55?

[Timothy B.]

Re: Melling oil pump

The M55 pump I have is exactly like the GM pump. A while back I posted about the GM showing how sloppy it's broached.

My 67 always held great oil pressure probably because the mains are undersize .001. I did not check all but going from the rear bearing that seems to be the case.

Of course the bearing may just be .001 on the bottom and standard on top closing the clearance .0005. I bet they are all .001 because of the idle oil pressure..

Also wanted to post the crankshaft is #4577 and has GMT cast into the rear of the crank. I thought all Flint engine cranks came from somewhere other than Tonawanda.

[John H.]

Re: Melling oil pump

The first photo below is the "weak" Melling pump you DON'T want, after GM mass-reduced the casting to save weight and cost; you can spot it by the ribs in the casting. The other photo is the Melling Select #10553 , which is the good old pump casting we're all familiar with - that's the one you want.

[Joe L.]

Re: Melling oil pump

The M55 pump I have is exactly like the GM pump. A while back I posted about the GM showing how sloppy it's broached.

My 67 always held great oil pressure probably because the mains are undersize .001. I did not check all but going from the rear bearing that seems to be the case.

Of course the bearing may just be .001 on the bottom and standard on top closing the clearance .0005. I bet they are all .001 because of the idle oil pressure..

Also wanted to post the crankshaft is #4577 and has GMT cast into the rear of the crank. I thought all Flint engine cranks came from somewhere other than Tonawanda.

Tim------

As far as I know, all small block forged cranks were manufactured at the Tonawanda forge. The only other forging operation that GM had at that time was the Detroit forge and I don't think they manufactured crankshafts there. It's possible they did, though.

[Timothy B.]

Re: Melling oil pump

Joe,

I have a early 63 short block in the basement with a 2680 crankshaft that I will rotate to look for the forging ID.

Always wondered why some of the cranks have the short # (2680, 4577) and some have the complete part number on the crank. Heck, I always wondered why two part #'s for the same crankshaft..

I always thought it was the hardened crankshaft/vs the non hardened but my 67 327/300hp car has 4577 which I believe to be the original crank but can't be 100% sure.. The long part # crankshaft is what I thought is non hardened but not sure now.

[Clem Z.]

Re: Melling oil pump

Joe,

I have a early 63 short block in the basement with a 2680 crankshaft that I will rotate to look for the forging ID.

Always wondered why some of the cranks have the short # (2680, 4577) and some have the complete part number on the crank. Heck, I always wondered why two part #'s for the same crankshaft..

I always thought it was the hardened crankshaft/vs the non hardened but my 67 327/300hp car has 4577 which I believe to be the original crank but can't be 100% sure.. The long part # crankshaft is what I thought is non hardened but not sure now.

the nitritied cranks are a gray in color

[Timothy B.]

Re: Melling oil pump

Thanks Clem,

Now that I think about it, the crank in my 63 was replaced and the crank has that grey color.

[Kenneth B.]

Re: Melling oil pump

The first photo below is the "weak" Melling pump you DON'T want, after GM mass-reduced the casting to save weight and cost; you can spot it by the ribs in the casting. The other photo is the Melling Select #10553 , which is the good old pump casting we're all familiar with - that's the one you want.

The light weight one must be a later version. I pulled the old prints out of my files. The old print dated 1-6-59 is M-55001 & lt lookes like the second picture. The second print is dated 4-6-79 with rev. dated 10-3-84 & is M-55011. It also outwardly lookes like the old one with some minor changes. I don't see a new design print that was M-55. The part # M-55 was deleted from the M-55011 casting but I don't know why.
KEN

[Timothy B.]

Re: Melling oil pump

I wanted to post some pics of the drain plug repair on my oil pan while everything is apart. After talking to the time-sert people and getting the price for a kit to install this time-sert I decided to use a heli-core to repair. The complete process took five minutes and I am very happy with the repair.

As far as the rear main cap and damaged dowel pins, I went to the machine shop and we removed two dowel pins from a junk block so I twisted the old pins out, broached the oil pump mating surface and installed the new pins to the correct depth. They fit nice and snug so everything good there.

I am going to have the pick up screen tack welded or brazed to the oil pump cap before assembling the oil pump.