Sampson

I remember reading in a thread not long ago to not use a high volume oil pump on a street engine 350 build but the poster did not offer any explanation. Any thoughts out there on this?

pogo69

You may not want to pump all that oil out of your 4qt pan

cutlassefi

It won't, had one in mine for years, no issues.
Just make sure all the drainbacks have been addressed.

Sampson

Appreciate the feedback guys. I already had purchased the pump when I read that thread. Had me worried but if you ran one without issues I will go ahead and use the one I bought.

MDchanic

In those situations where it has happened, oil starvation seems to have been the result of long periods of high-RPM use, like minutes over 5,000, which can happen in race applications, but pretty much never otherwise.

I have no personal experience with this, but that's my distillation of all the things I've read here and there.

I've got a HV pump that's been lying around that I will be putting into an old motor I'm going to be using - I figure if the bearing clearances are a bit large, this will keep the pressures up when it's hot and idling.

- Eric

joe_padavano

The "HV pumps suck the pan dry" myth is right up there with "headers won't fit Supremes". I've run one on a street-strip car with no problems whatsoever. The only time you'll POSSIBLY have a problem is if this is a high mileage motor with all the oil return holes coked up - and if THAT'S the case, you have a bigger problem.

Rickman48

Or - drain holes clogged with hardened and broken valve seals!

krooser

I have seen pieces of hard rubber valve seals plug an oil pump screen...

Sampson

That should not be a problem here as this is a going in a fresh rebuild. Clean with fresh seals etc. While we on on the oiling subject do you recommend expanding the oil holes in the bearings for better lube?

krooser

I matched the blocks oil passages to match the bearings... Take a good look at those main bearing galleries... They are likely mis drilled.

cutlassefi

They're not "misdrilled".
You can do it if you want to but matching all that stuff is entirely unnecessary.

Redog

I put a HV pump in my 330, but I also added a 7 quart pan as well

380 Racer

One of the best things about a HV pump is the fact that the pickup bolts on and isn't pressed in. I ran a stock pan for many years with the HV pump and NEVER pumped the pan dry.

gbodyfan

And now the next question to restrict or not to restrict?

380 Racer

I say yes. I have used the main to cam restrictors and saw no benefits but no problems either. I used restricted pushrods for years with my hyd cams. I currently use restrictors in the bores to limit the oil going up top. Big enough holes to let some oil thru to lube the lifters, but not flood the heads.

Redog

That is what I love about the HV pump

I have a stock pump, stock depth pick-up pressed in, somewhere

Kennybill

I've been refraining from commenting "but" a "street" 350 doesn't have oiling problems. A stock oil pump & pan is fine. When u get the pickup height where you want it, tack weld it. IMO, the hi-vol pump takes more power than a stock one so if it's not needed why use it. Those Oldsmobile engineers are looking smarter as I get older. Now on a BB Olds, if I had a hi-pump I would have a larger than stock (4 gt) oil punp, just for piece of mind. Ken

Octania

How many times have we gone over this?

The oil pump does NOT pump more oil THRU THE ENGINE because it [the pump] has more volume. Unless the pump cannot keep pace with flow- which is generally only at idle.

The pump [almost] ALWAYS provides more flow than can be forced thru the engine. The remaining flow dumps over the bypass back to the pump inlet.

So, a pump 10,000x as large will waste a lot of pressurized oil AT THE PUMP, but will not cause more oil to flow thru the engine, thereby "sucking the pan dry."

The pump output varies linearly [more or less] with RPM.
The oil passing thru the engine is [more or less] a steady rate, varying a little with the pressure developed by the pump, which at all speeds above idle should be the same 40 to 60 or whatever you set it to.

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