Inliners International Forums General Discussion Hi Performance oil pump

This being my first inline build , I need recomendations on oil pumps. I have a moderate 292 to be used for bracket racing. I`ve built a 7 quart oilpan with windage tray etc. Do I stick with the stock pump or try to locate a hi volume unit? Any advice from those with speriance would be nice. Thanks

How high do you plan to rev it? A rule of thumb is to allow about 10 psi for every 1000 RPM you plan to twist it.

If you are using a hydraulic cam and the rod bearing clearances are less than 0.0250" I'm guessing the stock pump will supply enough lube.

But Melling and TRW make inexpensive HiPo pumps so I'd say its cheap insurance with little downside, except maybe a smidge of horsepower loss and more stress on the distributor/pump drive.

You really don't need a hi-volume pump. Some have reported issues with the dist. gear using a Hi-volume pump. Myself I never had a issue when I use one , not even at 8000 rpm. But all
you need is a stock pump. and it to works just fine at 8000. I ran a stock pump for over 17yr Bracket Racing. Never had any problems.

I think the general rule of thumb of 10 psi for every 1000 RPM is not needed.

I had told Mike Kirby I used to turn my engine to 6500-7000 RPM range & only made 40 PSi of oil pressure , he said that is fine.

I would have like to see more like 50 PSI @ 7000 RPM, engine never blew up, had 12:1 compression turning 6500 RPM , switch cylinder head & put a blower on the same untouched lower end & ran to 7000-7500 RPM range & could not blow it up, this old engine is still in my Camaro, been sitting so long & want to freshen it up a bit.

MBHD

Crickets

MBHD

God, that's a lot of clearance! When I first read this I thought you meant .0025" vertical bearing clearance. Then, I thought you probably meant Rod side clearance.

Anyway, you're correct. Any reasonable clearance will not require a hi-volume or hi-pressure pump.

If I remember correctly, Panic gave someone a real whippin' about side clearance not having any effect on oil throw off and loss of pressure. I still like .020"

Yeah, Greg has the decimal point in the wrong place. Also as he said, if your running a hydraulic cam, a high volume pump wouldn't be necessary because they aren't going to realistically make HP much above 5500 or 6000 RPM, regardless of what the cam card says.

Good eye guys - I meant to say 0.0025 but now that I think of it about 0.0250 of side clearance is also common practice.

10/4 on the 10 psi per 1K revs thing - my 7200 RPM 4" stroke bracket motors only carry about 50 psi hot...

... but I know a 292 has a longer stroke than 4" and stroke and the amount of revs turned both impact the oil pressure requirements, as well as rod bearing clearances.

Guys,
To put a bit of a different spin on the high volume pump thing:
If the engine is getting a bypass filter added along with the stock filter would a high volume pump be a good idea?

Thanks

forgot to add that I have blocked off the oil filter bypass and am using a system one filter. Make any difference? And yes I am using hyd lifters.

You no longer have to worry about unfiltered oil circulating through the engine if the flapper valve sticks open, but shouldn't affect the output oil pressure you will see.

I bought a 40-65 oil pump spring for my upcoming build. I am using "camsaver" lifters that have a slot cut down the side to spray pressurised oil on the cam lobe. I know that the pump won't put out any more volume but I was thinking the spring might delay opening of the relief valve to a higher rpm. Plan on running 10W-30 oil. Does this seem like too much pressure? This spring is going on the stock pump. Jay 6155

Your overall pressure will be dictated more so by your bearing clearances than the relief spring. But 60 psi or so is fine.

Jay, where did you get that oil pump spring? I`m running an aftermarket HEI and am a little worried because it`s probably foreign made that it will not take the added pressure of a modified oil pump. thanks

Sparks, The spring came from Summitt Racing. Part# 22-150. Cost $2.97. I don't know how it will react because I haven't built the engine yet. I plan on using it in the stock oil pump. Jay 6155

You can shim the stock oil pump spring to raise the relief pressure. All you need is a bathroom scale, a drill press or other typr of press, a caliper, and a calculator:

Remove the spring.
Place it on the bathroom scale on the drill press table.
Measure the free length.
Apply varying loads by compressing the spring and reading the scale - lbs vs length.
This gives you the spring constant K.
Calculate the Area in square inches of the spring plunger by measuring its bore diameter.
For a given increase in pressure calculate the spring shim thickness needed: Pressure= K x (shim thickness) /Area.

We shimmed all of the stock pumps in the crate engines we built as well as all street performance engines with a .050" shim.

My friend would use a standard Holley jet to shim SBC standard oil pumps. All he does is builds engines for a living.

MBHD