Oil pump questions

[Joe C.]

Re: Oil pump questions

Dennis bought the better pump, the Melling Select, which has a heavier casting in the critical neck area. The present day M55 and the Sealed Power 224-4146 (standard volume-high or standard pressure) both use cheapened castings which were changed about 8 years ago. The original GM pump used the heavier casting, like the Melling Select, and which were used by Sealed Power and Melling's standard design up until about 8 years ago. The Melling Select is on the right; the M55 is on the left:



Here is a link to the Melling relief springs, the first FOUR of which are compatible with the Sealed Power standard pump, the M55 and the Melling Select. Click on "click here" to view:

http://www.melling.com/News/News/articleType/ArticleView/articleId/123/Performance-Oil-Pump-Relief-Springs-now-available-in-packets

[Gary R.]

Re: Oil pump questions

Here are the pic's from last month when I pulled off the SR Torquer heads. I just placed the head on the bench and came back a little while later to find the oil running out, then pulled the valve.








Here is #1 plug, good example of the dividing line on the plug. Intake fouled, exhaust white.

[Duke W.]

Re: Oil pump questions

Duke,

The Melling pump is a very nice part and the standard spring supplied with there M-55 pump is 58psi as I was told when calling a few years ago, that would be about right considering what I see on the gauge when driving my car. There is a provision in the cap for pin oiling and the casting seems nice and stout so changing to the GM spring may be all that's needed.

...trouble is, that 58 psi "standard spring" would only be suitable for late '63-up SHP/FI engines that have 80 psi dash gages. Virtually all other SBs, especially if they have a 60 psi dash gage have a 40-45 psi OE spring.

So, most owners would have to buy the pump and the spring kit and change the spring, but even the lightest green spring is rated at 49 psi, which is still higher than OE.

Another alternative is to buy the correct GM small block replacement spring:

3814903, 40-45 psi, most SB (60 psi gage,) 21 coils, 2 7/32" free length

3848911, 55-60 psi, SHP/FI w/80 psi gage, 21 coils, stripe of white

Of course. my first recommendation is to disassemble the OE pump and inspect it. Unless the pump has ingested debris there is usually no or very little indication of wear. It's easy to do. I demonstated how to disassemble and inspect an oil pump at the bar during out last SoCal Chapter meet.

If you're into precision and like to work in the garage you can measure gear end play and reduce it to two to three thou as discussed in "How to Hot Rod Small Block Chevys". Snug end play will prime the pump faster on startup.

Duke

[Joe C.]

Re: Oil pump questions

Here are the pic's from last month when I pulled off the SR Torquer heads. I just placed the head on the bench and came back a little while later to find the oil running out, then pulled the valve.








Here is #1 plug, good example of the dividing line on the plug. Intake fouled, exhaust white.

Gary,

It's NOT a good idea to use RTV around intake ports, including water ports because RTV is attacked by gasoline, and will encourage gasket creep.

If you continue to have problems, I recommend that you use a steel core laminate gasket, such as Fel Pro 1278S or 1205S3

[Wayne M.]

Re: Oil pump questions

Not trying to hi-jack this thread, but you guys are discussing a topic that I have questions on. Melling 77-HV stamped on tab under a cover bolt. Off a mild '65 396, but engine obviously rebuilt at some time, but to what performance level I don't know.

Oil pump has been apart on my bench for a couple of years, and I've forgotten the order in which the pieces need to be reassembled. I assume the large end of the spring is at the retention pin (ie. outer) end, and the disc that the pin contacts has a depressed center that faces the inner (small) end of the spring. Correct so far ?

This spring has 25_1/2 turns, end-of-wire to e-o-w. Looks to have a coating of very light pink or beige paint (see last 2 pics). Does this tell us anything about what pressure it might be rated at ?

Are Melling small block and big block springs color coded, interchangeable, and rated the same ?

[Joe L.]

Re: Oil pump questions

Here are the pic's from last month when I pulled off the SR Torquer heads. I just placed the head on the bench and came back a little while later to find the oil running out, then pulled the valve.








Here is #1 plug, good example of the dividing line on the plug. Intake fouled, exhaust white.

Gary------


Did you also find oil in the intake manifold plenum and runners?

[Dick W.]

Re: Oil pump questions

Gary,

It's NOT a good idea to use RTV around intake ports, including water ports because RTV is attacked by gasoline, and will encourage gasket creep.

If you continue to have problems, I recommend that you use a steel core laminate gasket, such as Fel Pro 1278S or 1205S3

I have used a quality RTV sealant around intake gaskets since it became readily available in the automotive trade and had no problems what so ever.

[Joe C.]

Re: Oil pump questions

I have used a quality RTV sealant around intake gaskets since it became readily available in the automotive trade and had no problems what so ever.

RTV works if the mating surfaces are perfectly flat and the ports line up well. Aftermarket heads/manifolds may cause some misalignment or if OE deck height or head locating points are different, fuel can and will penetrate and once intrusion begins, leaks/gasket failure and creep will follow in short order.

[Gary R.]

Re: Oil pump questions

Joe & Joe, I did not find any oil in the intake runners. The blue material you see around the intake runners is not RTV but rather Permatex Hylomar. I used it the 2nd time around to hold the gasket in place because I was concerned it would have moved. The Hylomar is fuel resistent and pretty much like contact cement, this time around I used Gasgacinch which is also contact cement. I have used RTV around the water ports and on the china walls for the past 30 years.

[Dick W.]

Re: Oil pump questions

RTV works if the mating surfaces are perfectly flat and the ports line up well. Aftermarket heads/manifolds may cause some misalignment or if OE deck height or head locating points are different, fuel can and will penetrate and once intrusion begins, leaks/gasket failure and creep will follow in short order.

I was just starting past experiences with engines that I know, within reason, did not have perfect alignment. One of the applications was medium duty truck engines that almost invariably had cylinder heads milled at least one, if not multiple times during their useful life. The intakes were never angle milled. The trucks were loaded to max GVW and we'll over at times. The trips were from twenty to one hundred miles. At night the entire exhaust system, to the end of the tip would glow cherry red, an application that would greatly exceed the requirements of any street engine and of the majority of common race engines. There were NEVER any problems with RTV sealers.