What is the benifit/trade offs of using a high volume over a stock replacement oil pump? What else would you do if you install one. I have the motor out to replace a broken motor mount and put new heads on.
Should I spend the money on the oil pump or a high flow water pump? (or both)


[Modified by redwingvette, 8:28 PM 9/30/2002]

 

i would get a regular oil pump and a high volume water pump...my 2 cents


'74 L-48
4 speed

 

It depends on what your pressure was with the pump you have in it now. Oil pressure can drop because of two reasons. One is wear in the oil pump and the other is wear in the crank and cam bearings. If your pressure was OK before you pulled the engine I wouldn't worry about it. If pressure was dropping it's a good bet it's bearing related rather than oil pump wear since oil pumps are pretty solid pieces. While the engine is out I would take a look at the bearings and if they need replacement I'd do that first. Same goes with the water pump. If you were having problems before then going to a new pump "may" help but there are a lot of factors that can cause a car to heat up besides the water pump. More info might get you better answers.

 

Use of a high volume oil pump with a stock volume oil pan puts you at risk of oil pump cavitation, inadequate lubrication and spun bearings. This happened to me a few yers back.
For street use, use a stock GM oil pump, open up the return passages in the heads, use high quality oil, change frequently and use a quality filter.

 

Thanks for the replies. I rebuilt the motor two summers ago and the oil pressure was fine as long as the motor temp stayed below 195-200. With the air on and in traffic she would run as high as 220-230 and the oil pressure would drop at idol. I have never used a high volume oil pump or water pump so I didn't know what to expect. I think I will stay with what I got and up grade the radiator instead.

 

Brian,
One thing to keep in mind is that Chevy never used a high volume pump on any of its SBCs. In fact they only used a high pressure pump on some solid lifter engines. Unless you are building an all out race engine I would stay with a stock type pump.

tom...

 

Thanks Tom. By the way, nice web site. I have you marked in my favorites section. Lots of good info.

 

I agree. I installed a new GM standard volume pump too, but I improved it a bit. I lapped the cover face and pump body face to reduce the gear end-clearance to the minimum spec (.003 I think…), and this also removed the original machining lines, thereby improving pump sealing and efficiency a little bit. Use the stiffer relief spring if supplied with the pump. Don't let the sales guy talk you into a high-volume pump unless you have a heavily modded motor.

 

I agree on the stock pump also. I have a theory that the high volume oil pumps put an additional load on the rear oil seal; thus contributing to rear oil seal leaks. I have spoken to Melling reps about this but they don't agree. Of course they want to sell oil pumps. My engine had a high volume pump and developed a rear seal leak (small) but still fustrating. The car is in restoration at this time and I jsut got the block back from the machine shop. This time I ordered a stock replacement pump. I'll see whether or not the rear seal develops a leak. I know its a small sample size, but it's at least one data point!
:flag :smash:

 

I guess I'll chime in again and be the dissenting vote. I've had a high volume high pressure oil pump on my car for about 3 years now. I typically run about 60 to 70 pounds pressure on the highway and about 40 pounds at idle. I've driven the car for hours at 70 mph and 3000 rpm or better and the pressure never fluctuated. After i rebuilt the engine I had a leak at the rear which I thought was a rear main leak but turned out to be a combination of loose valve covers and a bad seal on the oil pan, neither of which are related to pressure. I use 10W30 Mobile 1 which may or may not make a difference and I have World Products SR Torquer heads which may or may not drain better than stock heads. I'm not saying one way is better than the other but I've heard more people worry or complain about too little oil pressure than too much. No flame intended, just an opinion.One thing I would try to resolve are the high temperatures you are experiencing. My car, without the air running runs 160 degree whether in traffic or on the highway even in the hottest weather. With the air on it will run about 180 around town and about 190 to 200 on the highway. This is during 90+ degree weather. This is with a stock water pump, 160 degree thermostat and stock radiator which is about 12 years old.


[Modified by vettfixr, 1:21 PM 10/1/2002]


[Modified by vettfixr, 1:26 PM 10/1/2002]

 

I'm with vettfixr. I always use high volume pumps in all my rebuilds. I like the extra margin. Hot my engine idles at 45-50 pounds and at light cruising 70 pounds. I also tend to add extra oiling holes like behind the timing gear on the block and the housing in the distributor. I would rather see my gage on the high side then on the low side.
I also run a high volume water pump running 30% over crank shaft speed.

 

I've done the same on about half of the 6 rebuilds I've done so far. I think the value of the pump is overratted, there isnt any harm done, but from everything I've ever read, from people such as Smokey Yunick and John Lingenfelter, seems to indicate that it simply inst necessaary, the small block chevy oiling system is as near to bulletproof as a production motor comes.

When I rebuild the present motor it will get an oem pressure/volumn pump, however i will have the anti-cavitation grooves ballmilled into the cover plate to increase the efficiency of the pump.

BTW when you install these high pressure/volumn pumps dont forget to block off the bypass at the oil filter adapter - if you dont - very little of your oil will get filtered, as 70 psi will hold that dog right open.

this is the guy that bolts to the oil filter boss on the engine block and contains a bypass valve - the spring is designed for factory pressure pumps - if you run a hhigh pressure or high volumn pump you will most likely be in bypass mode most of the time.

Remove the bypass valve and replace with a pipe plug - this will force all oil (at whatever increased pressure) through the filter media in the filter.

 

I talked to an engine builder, and he says he puts high volume pumps in all of his engines, street and racing alike. In a street car, the benifits probably won't be much, but it definently wouldn't hurt.

Jerry

 

I think the only disadvantage is a high-volume pump could suck the pan dry under a worst case scenario, such as during a long fast corner, and if the oil level is too low. Also, if the oil galleries are not flowing well or if the return passages in the heads get clogged, a high volume pump could cause a problem. If you use a high volume pump, just be sure the rest of the system is ready to cycle the extra oil. A bigger sump is always good.

 

I used a Melling Highflow Oil Pump in my BB rebuild. No RMS leaks. 50 psi at idle and 70 psi at 2000 rpms. I went this route because i have an oil cooler in front of the radiator and figured the extra pressure to force the oil thru , would be a good thing. Also had the Block oil journal outlets chamferred (45 degree) which i hear is a wise move.

RR

 

I run high volume pumps on both my vette and streetrod. As others have stated, the high volume pump can and will likely suck the oil pan dry at one point or another. This caused me to spin several bearings in my streetrod years ago due to lack of oil. With my vette, I almost did the same thing. I happened to look down at the pressure guage as I reached redline in second gear and saw the oil pressure droping quickly. :eek: I now use Moroso 7qt pans on both cars and this problem in no longer an issue.

Also, the addition load on the lower distributor bushing from turning the high volume pump will do some damage. I have destroyed the lower bushings in the distributors of both cars after several years of use. I still run the high volume pumps in both cars, but I now must plan on repairing the distributors every so often. That's just the price of going fast :smash: :smash:

 

To help the lower bushing I drill a 1/8th hole through the distributor body between the 2 lower machined surfaces. This allow pressurized oil to enter the lower part of the distributor and wash this bushing down with oil. I also file a small slot in the lower machined surface to allow pressurized oil to squirt down over the cam and distributor gear.

 

So let me put on my "sarcastic" hat for a minute. In order to use a high volume pump, I should modify the distributor body, run a larger oil pan, add extra oiling holes behind the timing gear on the block, block off the bypass at the oil filter adapter. Anything else? And what exactly is the "problem" we're trying to solve with all this? As stated by others, the SBC has an excellent oiling design, not prone to failure. Seems like throwing way time and money trying to fix a non-existent problem to me.

It may make sense on a race/competition engine, but I tend to believe that the multitude of GM design engineers would have designed it differently if a street engine needed more oiling volume/pressure. Nearly 50 years of SBC street applications including the LT-1, fuelie motors in the '60's, etc did just fine with the standard pumps.

This is just my opinion, I may be wrong :D :jester
Shannon

 

[QUOTEIt may make sense on a race/competition engine, but I tend to believe that the multitude of GM design engineers would have designed it differently if a street engine needed more oiling volume/pressure. Nearly 50 years of SBC street applications including the LT-1, fuelie motors in the '60's, etc did just fine with the standard pumps.

This is just my opinion, I may be wrong :D :jester
Shannon [/QUOTE]

The LT-1 and some of the other hi-perf 327's all used factory installed high volume pumps. I'll agree that it is overkill for mild street motors, but on anything that revs, it is needed.

 

It was my understanding that Chevy never used a High Volume pump in any street/production engine. But they did use a High Pressure pump in a few solid lifter engines but never in a hydraulic lifter engine.

tom...