[Scott Stoneburg]

Originally Posted by Scott65

It works because of the high and low pressure areas in the pump cavity. Not trying to get involved in the arguement, but you asked... Pump theory isn't particular to Pontiacs, or even combustion engines.

Glad you chimed in. I had to re-read and think about what's being said. I got hung up on labeling the holes "feed" and "drain" really the holes will alternate being each. So I'm assuming that's why to put them high on 1 side of the gear and low on the other. But the holes will still not be exactly 180 from each other, I got hung up on that point too. They will be 2 teeth apart.

[Scott Stoneburg]

This is a picture of a gear with the feed hole drilled in it. This isn't mine but I used this as an example when I was looking at what mods to make to mine. The 2nd picture is something I didn't do yet. Its a groove to feed oil to the pump drive shaft. You all think this is worth adding?

[73 TRANSAM]

I was going to do that groove but my engine builder told me that I do not need a leaker on that area. He said that the oil pump is pressurized on that area so it will lube itself. I like what you did on your oil pump. I did the same thing on my oil pump. I had a 7/8" thin wall and bend it and tig weld a BBC conical pick up head. Then I plugged the bypass and used an external Petersen oil regulator so I can set my oil pressure externally. Great Job!

[Scott65]

I wouldn't feel good about that groove down the bore of the drive gear. The other one "might" help oil the shaft, but it might add thrust too. I'd skip it too. If you feel really strongly about it, make it really small, both width and depth. The shaft clearance is gonna determine oil flow through there anyway...

[Scott Stoneburg]

Finished with the pump, didn't do the groove to feed oil to the drive gear/shaft like in my last picture posted. I made a block off plate and ran the pump with an electric 1/2" drill. Bypass opens up at 65 lbs. I feel comfortable with that. So its good to go

[hurryinhoosier62]

Originally Posted by Dragncar

Since I have ran Pontiacs for more than 35 years, street raced and raced at the track and never blown a head gasket, spun a rod bearing much less blown up a engine, I think I am good.

I know its a small thing, does not mean a lot. But how are you going to drill holes 180 deg apart on a idler gear unless you drill through the "tip" of a gear. I am assuming you drill the holes at the bottom of the Vs. Look at the pic of this idler gear on this Melling Pontiac 60lb pump. What is that 150-160 deg V to V. So the balance will always be out, you are removing weight unevenly.
I
The oil is getting crammed into the hole when the 2 gears mesh. How can there be any positive in- out flow of oil ? I just think if you drill 2 holes oil is getting crammed into both of them and there is no "flow" between the 2 because the hole you think of as a exit hole is getting oil shoved in it every time it makes a revolution in a millisecond.

Centrifugal force and windage effect. You might want to study BASIC physics. HOW do you force pressurized oil into a passage with no low pressure area to relieve the pressure of the incoming oil. Answer: you DO NOT. That is function of the second hole opposite of the feed hole: to create a low pressure area for the oil to flow to that will not re-pressurize it. Then again, you DID believe you can grind hard chrome off a crank journal.....

[hurryinhoosier62]

Originally Posted by johnta1

Isn't the oil pump immersed in oil?

John, yes it is but that does NOT ensure the idler shaft gets adequate lubrication. This is WHY I was taught by two engine builders with one NHRA world championship and two USAC National champships between them to perform this modification. I don’t make it a habit of arguing with success.....

[Mike Davis]

Along with the pump mods and 9/16 ball, something that I have been doing lately is using a 1/2 ball hone on the block passages, filter passage and the pump passage. I start with a 120 grit then a 240 grit and finish with a 320 grit with light cutting fluid. Gets rid of any rust, scale etc. Seem to really shine up the passage.

[Scott Stoneburg]

Originally Posted by Mike Davis

Along with the pump mods and 9/16 ball, something that I have been doing lately is using a 1/2 ball hone on the block passages, filter passage and the pump passage. I start with a 120 grit then a 240 grit and finish with a 320 grit with light cutting fluid. Gets rid of any rust, scale etc. Seem to really shine up the passage.

Where do you get the 9/16 ball? I honed the oil pump shaft passage but not the block yet

[Mike Davis]

I bought the ball at ACE hardware. Home Depot had them as well.

[Scott65]

The 9/16 ball is a good mod. Will lessen the likelihood of having it hang...

[t money]

Don’t forget to install a .060 harden washer behind the spring to keep your 60 or 80 pump output when using the 9/16 ball. This is a good read. Thank to all involved

[Scott Stoneburg]

I'll see if I can find a 9/16" ball. I put a hardened washer in already. I may play with adding more washers. Initially I was thinking 65lbs is good. But I think I'll mess around and see if can tune the pressure closer to 70lbs.

[Mike Davis]

I like a .090 washer using the 9/16 ball. Warm idle with 10w-40 Royal Purple XPR is around 30PSI with 70PSI going thru the traps at 7200RPM.

[Dragncar]

Racers used to cut the spring in a SD 80lb pump to get it to a 70lb pump. Whittmore told me about the mod, but don't remember if it was 3/4 a turn cut off or 1 1/2 cut off. I have a Dyna Gear 80lb pump and it comes with everything, spring cap ect to make it into a 60lb pump. Kind of a nice option, cast bottom plate too. AND the hardened shaft with dimple in the right place.

[Dragncar]

Originally Posted by hurryinhoosier62

Centrifugal force and windage effect. You might want to study BASIC physics. HOW do you force pressurized oil into a passage with no low pressure area to relieve the pressure of the incoming oil. Answer: you DO NOT. That is function of the second hole opposite of the feed hole: to create a low pressure area for the oil to flow to that will not re-pressurize it. Then again, you DID believe you can grind hard chrome off a crank journal.....

You know since you chimed back in the thread you said you were out of, those panties will feel a lot better if you just give them a tug. Must be all bunched up.

[Scott Stoneburg]

Originally Posted by hurryinhoosier62

John, yes it is but that does NOT ensure the idler shaft gets adequate lubrication. This is WHY I was taught by two engine builders with one NHRA world championship and two USAC National champships between them to perform this modification. I don’t make it a habit of arguing with success.....

Not arguing with success either. Just trying to learn. So wouldn't there be enough oil flow forced out through the top and bottom of the shaft?

[Scott Roberts]

Not being an ass but.... I understand you guys making things better but I ran a melling pump on a stock block and nodular crank at 7000 rpm for years with no failure...
At a point I think it's getting over analized...just my opinion.

[Scott Stoneburg]

Originally Posted by Scott Roberts

Not being an ass but.... I understand you guys making things better but I ran a melling pump on a stock block and nodular crank at 7000 rpm for years with no failure...
At a point I think it's getting over analized...just my opinion.

That is very possible. I have had several other motors over the years, never had anything but a out of the box Melling pump. But I'm just looking to make improvements and learn a little

[Scott Roberts]

Originally Posted by Scott Stoneburg

That is very possible. I have had several other motors over the years, never had anything but a out of the box Melling pump. But I'm just looking to make improvements and learn a little

I completley understand.... like I said, not being an ass... I do understand wanting to make a product better.... I do it every day at work...