[Johnny406]

So I've been hearing about modifying a Pontiac oil pump (M54D here) with a smaller 9/16 steel bearing over the factory 5/8 bearing to prevent trash from allowing the check ball to control low idle pressure. I had that happen to me years ago and it sucked to do all that work to remove a small piece of RTV that broke away from the pan gasket.

Anyways, I ordered some 9/16 steel bearings and measured and found a .0645 difference. I have a. 115 thick shim to compensate and hopefully bump up the pressure a bit.

Am I thinking/doing this right? The factory ball is on the left, 9/16 on the right.

[Mike Davis]

Yes, I usually try to find a washer somewhere around .100 or so.
I do the 9/16 ball mod to all my pumps.

[DOC]

did the same thing... Got the ball bearing at ace hardware. No issues at all.... did use a thicker hardened washer to take up some space.

[Johnny406]

Thank you Gentlemen!!

[steve25]

Since the pump spring is very hard metal the washer needs to be just a hard.

Take your chosen plain steel washer, heat it to red orange hot and quench it in oil to temper it harder.

If you choose not to go this route then at least polish / round over the sharp flat leading edge on each end of the spring.

[Half-Inch Stud]

Clever for hearing of this for the 1st time. I simply never thought of a smaller ckeckball.

Never( aware of ) having the stuck ball problem. Butt hay, a little visual inspection of the ball-seat-flow pocket relationship is a darn good idea.

Thick cold oil at startup has to be a design driver, and would promote a right-sized ball. Hmmm

[ponjohn]

Originally Posted by steve25

Since the pump spring is very hard metal the washer needs to be just a hard.

Take your chosen plain steel washer, heat it to red orange hot and quench it in oil to temper it harder.

If you choose not to go this route then at least polish / round over the sharp flat leading edge on each end of the spring.

That's what I was wondering, what do you shim.

[Mike Davis]

Originally Posted by ponjohn

That's what I was wondering, what do you shim.

You put the washer between the spring and the spring cup that threads into the pump housing. Normally to raise pressure you need a .062 washer if using a stock check ball, since the 9/16 ball is .062 smaller you need to go at least .100.

[Johnny406]

Originally Posted by steve25

Since the pump spring is very hard metal the washer needs to be just a hard.

Take your chosen plain steel washer, heat it to red orange hot and quench it in oil to temper it harder.

If you choose not to go this route then at least polish / round over the sharp flat leading edge on each end of the spring.

I didn't think of that, thank you!!

[taff2]

I've never used a smaller ball in any of the pumps I've used,and never had a problem with the ball. If you have debris floating about in the engine that's big enough to hold the ball off it's seat- then you've either been sloppy when building it or you already have a parts failure/wear situation.IMO.

[Skip Fix]

My factory ball and a ARP hardened washer under the spring 0.060 runs about 75 psi through my whole run looking a the data logger.

[mysticmissle]

skip what do you use for a data? what else are you monitoring?

[ponyakr]

That's cool. I've read where LOTS of guys have said you don't want high pressure. all you need is what the out of the box M54DS provides. They talk about how much stress extra oil pressure will put on the oil pump driveshaft, as well as the dist & cam gears. Some even talk about bearing wash out.

But, me & a lot of other guys have been shimming the spring for more pressure, since way back in the old days.

But, Scott Burton said his RAIV Stocker engine just ran the stock pressure, and I think his engine would turn 8000 rpm. He made at least one 9 sec pass with it. And I think he said he ran 0w-10 oil. He said it's all about the bearing clearances.

http://www.hotrod.com/articles/hppp-...tiac-firebird/

So, opinions differ on oil pressure, as well as LOTS of other stuff.

[Stan Weiss]

Originally Posted by Half-Inch Stud

Clever for hearing of this for the 1st time. I simply never thought of a smaller ckeckball.

Never( aware of ) having the stuck ball problem. Butt hay, a little visual inspection of the ball-seat-flow pocket relationship is a darn good idea.

Thick cold oil at startup has to be a design driver, and would promote a right-sized ball. Hmmm

Mark,
Would you have any tools that would show the change in seat contact load from a 5/8" ball in a 5/8" seat to a 9/16" ball in a 5/8" seat?

Stan

[Half-Inch Stud]

Originally Posted by Stan Weiss

Mark,
Would you have any tools that would show the change in seat contact load from a 5/8" ball in a 5/8" seat to a 9/16" ball in a 5/8" seat?

Stan

Could develop a simple contact area calc. The ball dia ought have a matching seat angle: bang-to-fit may be ideal but takes some skill and attention. THEN ya measure the seat contact for Seal area (1 calc for a fun fact). And the 2nd calc to measure the net ID for the PSI hold (releae) force, assuming a Contamt (Liner) Spring Force.

--> Likely that the pump cat bypass ID is the value to use for Ball PSI calc (a disc area from diameter, not a sphere area).

Oh, i used to shim the spring for "a little more" and even > 100 Psi cold-start, 80hot when i tried Fully-Grooved Main Bearings. I've learned to calm down to 60 psi stock pumps and put concern to prevent oil starve, and use ths Spott scraper to feel good about it.

[Skip Fix]

Originally Posted by mysticmissle

skip what do you use for a data? what else are you monitoring?

RPM data logger. Measuring oil pressure, fuel pressure, g force, AFR, engine rpm, driveshaft rpm.

Dyno was about the same on their gauge also.

I tried to measure spring pressure on some different pump springs with one of those vise valve spring gauges-pretty soft springs so I don't think I got valid numbers.

[JSchmitz]

Originally Posted by steve25

Since the pump spring is very hard metal the washer needs to be just a hard.

Take your chosen plain steel washer, heat it to red orange hot and quench it in oil to temper it harder.

If you choose not to go this route then at least polish / round over the sharp flat leading edge on each end of the spring.

Be careful with "home" heat treating! I've hardened metal at work using powdered materials with total failure. The parts broke like glass. I'm certainly not an expert on this. But do NOT recommend hardening your own parts for engine assemblies! You can buy hardened washers cheap.

[Johnny406]

I'd like to bump mine up a touch as I will be using a roller cam and will push 6500-7000 (if the motor is still making power). Of course, bearing clearance is a influential factor.

[Richie Hoffman]

my engine had over a thousand runs on it when i pulled to freshen last year made 58 lbs oil psi at 7000 just a m54 ds pumps bearings looked like new i was surprised made about 650 hp went 8.95 @152 in 2400 lb car engine was as consistent as the day i put it together

[PAUL K]

Originally Posted by Richie Hoffman

my engine had over a thousand runs on it when i pulled to freshen last year made 58 lbs oil psi at 7000 just a m54 ds pumps bearings looked like new i was surprised made about 650 hp went 8.95 @152 in 2400 lb car engine was as consistent as the day i put it together

You should do the oil pump modifications and next time you could go over two thousand runs.