[Old Goat Racer]

Anybody know the diff. between a Melling and a Sealed Power pump? Summit shows the SP at $9 cheaper.

[chiphead]

I'm guessing there's probably subtle differences in the machining. You could probably buy the sealed power and put the 9 bucks toward the heavy bottom plate, the checkball mod and the other reworked all those pumps need. Somewhere on here there's a review I did of the melling select pump.

[Tom Vaught]

I used to buy the 60 psi pumps (when everyone HAD TO HAVE the 80 psi oil pumps).

Price difference for the 80 psi 455 SD pumps was quite a bit higher as everyone wanted one of the things.

I used to buy the 80 psi Spring and the Extended Spring Retainer Cup (from Melling) and swap the parts.

($5.00 for the 80 psi Spring and the Extended Spring Retainer Cup) and 10 minutes of my time and sold
a bunch of the "455 SD Oil Pumps" for a nice profit.
BUT I had access to a Melling guy who would sell me the parts as I was a WD for them.

Now some people are swapping the factory oil pressure ball for the 9/16" ball (a Butler Modification).
The 455 SD spring is so long it maybe drops the psi in the system with the smaller ID ball a slight amount
BUT the check ball controls the by-pass function of the oil pump. The spring sets the running pressure.

Just saying.

Tom V.

[chiphead]

https://forums.maxperformanceinc.com...hlight=melling

[Old Goat Racer]

An "old timer" once told me just put a .060 washer under the spring and ya got a 80# pump.
Pros/cons ??

[Tim Corcoran]

I put a .100 washer between the end cap and the spring gives me about 70 PSI

[PAUL K]

We use .060-.120 worth of shims in the 60# pumps all the time. Not sure I would say adding a shim makes it an 80# pump. The 60 and 80# pumps are set up to have similar oil pressure at idle. Adding a shim to a 60 lbs. pump will raise pressure across the board. So you will have more pressure at idle with a 60# spring and shim than a 80# pump without a shim.

[Bill Hanlon]

Originally Posted by PAUL K

So you will have more pressure at idle with a 60# spring and shim than a 80# pump without a shim.

I don't understand. Unless the engine idles at more than 60 psi there shouldn't be any difference.

[Cliff R]

Folks should realize here that the additional pressure is not needed, and it robs power from the assembly. Also consider that the distributor gear has to drive the pump, which is driven by the camshaft and timing set.

So you are loading the distributor gear harder as well as the timing chain and gears.

I've found that these engines, when correctly clearanced and assembled do NOT need more than 60PSI oil pressure. Even the "high end" full race engines I've done well over 700hp use stock Melling 60PSI pumps in them with zero issues in long term service.

In any case an 80 PSI pump would be over-kill in a street engine build and just knock the distributor gear out quicker......FWIW.......

[Steve C.]

http://www.wallaceracing.com/oil-pump-hp-calc.php


.

[srmmmm]

Originally Posted by Cliff R

Folks should realize here that the additional pressure is not needed, and it robs power from the assembly. Also consider that the distributor gear has to drive the pump, which is driven by the camshaft and timing set.

So you are loading the distributor gear harder as well as the timing chain and gears.

I've found that these engines, when correctly clearanced and assembled do NOT need more than 60PSI oil pressure. Even the "high end" full race engines I've done well over 700hp use stock Melling 60PSI pumps in them with zero issues in long term service.

In any case an 80 PSI pump would be over-kill in a street engine build and just knock the distributor gear out quicker......FWIW.......

For the last few years, I've participated with three different Trans Am series race teams running both the TA and TA/2 class cars (850HP and 495HP respectively). The TA engines sometimes hit 9200 RPM. Peak oil pressures from their dry sump systems I've seen on the data logging is about 75 psi, but they are averaging 65-67 most of the time. Granted they're probably moving a much higher volume of oil through the engine, but it just shows you don't necessarily need 80 psi. Two of the photos show a Childress Racing TA engine. The yellow car is a TA/2 engine which is fuel injected.

I always get smiles from the teams when I show up in Pontiac racing apparel.

[Old Goat Racer]

Where does a guy find one of these .060 shims ?

[PAUL K]

Originally Posted by Bill Hanlon

I don't understand. Unless the engine idles at more than 60 psi there shouldn't be any difference.

To put it in simple terms; both pumps are designed to have 20 psi at idle and 60 or 80 lbs. at high RPM. When you shim either spring it increase the pressure across the board.... So now you might have 25 psi at idle and 70 or 90 at high RPM.

[PAUL K]

Originally Posted by Old Goat Racer

Where does a guy find one of these .060 shims ?

We buy ours from ARP.

[Bill Hanlon]

Originally Posted by PAUL K

To put it in simple terms; both pumps are designed to have 20 psi at idle and 60 or 80 lbs. at high RPM. When you shim either spring it increase the pressure across the board.... So now you might have 25 psi at idle and 70 or 90 at high RPM.

Paul: Your statement said that by shimming the spring you would increase the idle PSI. As a properly operating spring and ball have no effect until the relief pressure is met (either 60 or 80 PSI) how would shimming the pump increase idle pressure?

[Tom Vaught]

TRUE. LOL!

Tom V.

[steve25]

It’s so interesting that many of the SS guys who run 3” mains build for .002” max on the rods and mains and free up a bunch of hp by running only 45 psi and without issue.

[PAUL K]

Originally Posted by Bill Hanlon

Paul: Your statement said that by shimming the spring you would increase the idle PSI. As a properly operating spring and ball have no effect until the relief pressure is met (either 60 or 80 PSI) how would shimming the pump increase idle pressure?

I'm not sure on that..... Depending on the amount of shims we usually see 5-15 psi increase across the board.... Maybe we are doing something wrong?

[Old Goat Racer]

Originally Posted by PAUL K

We buy ours from ARP.

Would you have a part number or a link ?
Thanks, OGR

[PAUL K]

Originally Posted by Old Goat Racer

Would you have a part number or a link ?
Thanks, OGR

ARP 200-8643