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Old 09-13-2008, 09:17 AM
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Big block pil pump on small block Chevy

I'm freshening up my 400SB Chevy with new rings and installing a set of used Vortec heads. Just for insurance, I am going to discard the old oil pump and install a new one. Here's my question...can I install a BB oil pump? If so, do I need a different length intermediate shaft? I like the idea of the big block pump having more gear teeth and producing slightly more oil volume without being much harder to turn than the small block pump....Do you gents agree?

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Old 09-13-2008, 11:23 AM
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I completely disagree. If the bearing clearences are correct, the small block pump is more than adequet. The big block pump will consume about 12 horsepower or more to drive. High volume pumps are only band aids to cover up excessive clearences.
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Old 09-13-2008, 12:17 PM
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What he said.
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Old 09-13-2008, 12:28 PM
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Its all a moot point anyhow,big block & small block oil pumps are not interchangeable.And as to DoubleVision's statement that a high volume oil pump takes 12 or mor hp to drive,I would have to see a back to back dyno test beforeI would believe it.
Guy
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Old 09-13-2008, 12:44 PM
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Quote:
Originally Posted by Guy Hiltz
Its all a moot point anyhow,big block & small block oil pumps are not interchangeable.And as to DoubleVision's statement that a high volume oil pump takes 12 or mor hp to drive,I would have to see a back to back dyno test beforeI would believe it.
Guy
Interesting isn't it?

You can prime an engine with a battery drill with cold room temperature oil, and yet some say it takes a million horsepower to turn the pump.

I use a 3/8 electric drill that free spins 2800, and I guess at least 2000 under load (4000 engine rpm)..... and it sure isn't a 12 hp drill.

Tests by pump manufacturers on their pumps showed that high volume pumps draw almost zero additional power since the additional volume is bypassed. The tests also showed that the bypassing oil creates almost no additional oil temperature increase.
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Old 09-13-2008, 12:51 PM
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Yes you can run a BB pump in the SBC and I've done it for years. The shaft is Moroso 22090
Quote:
Moroso 22090 - Moroso Oil Pump Shafts Details

# Can also be used in SB-Chevy or 90 Chevy V6 engines to compensate for reduced distance between main bearing centerline and distributor shaft tang when block deck has been cut and main bearings line-bored.
# 400 cubic inch small blocks must be machined to accept these Oil Pump Shafts The oil pump shaft opening must be enlarged to a 9/16" dia.
An M-77 pump is not high volume.

Also, roundy round guys have been doing this forever, it is not done to mask or cover anything up.

As for any eatng up of a few HP, it wouldn't be noticeable in a 500+ HP app. I'd look at any improvement in oiling as a plus. If the SBC pump was so good, why does the BB pump have more spur gears? Why didn't GM use the SBC pump in the BB?
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Old 09-13-2008, 12:54 PM
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Thanks scot for bringing that up. I run hi volume pumps on all my rebuilds, and never a problem. Did not know about the bbc swap, thanks for info.
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Old 09-13-2008, 01:07 PM
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Quote:
Originally Posted by ScoTFrenzel
Interesting isn't it?

You can prime an engine with a battery drill with cold room temperature oil, and yet some say it takes a million horsepower to turn the pump.

I use a 3/8 electric drill that free spins 2800, and I guess at least 2000 under load (4000 engine rpm)..... and it sure isn't a 12 hp drill.
No, but since the drag on the pump is exponential, (a function of the square of the speed and the pressure based on viscosity) and the pump spins the same speed as the engine (double the cam speed), try spinning that pump to 6000 with some cold 10w40 in the case. Now you've quadrupled the pressure, which (other factors excluded) has multiplied the drag on the pump by at least a factor of 16 - and that is simply from the oil pressure. That doesn't take into consideration the exponential increases in friction on the driveshaft, the drive gear on the cam, and the gerotor friction inside the pump.

People say the same thing about alternators because they spin so freely. Put a load on them and spin them to 5000 rpms and then see how freely they spin.

Oil pumps take considerable HP to run. Otherwise, why would manufacturers use a heat-treated chrome-moly 3/8" shaft to drive it?
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Old 09-13-2008, 01:24 PM
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There are other alternatives for pumps, the BB pump is just one of them. If you want a really good pump buy a Titan. The idea of more gears in the BB pump was one plus of running it in the SB, thinking like this anyway - more gears equals more pulses per revolution... helping to eliminate, or distribute those pulses more evenly, diminishing the larger pulses from the SBC pump that might wreak havoc on the distributor and spark timing. I like to run them just because.
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Old 09-13-2008, 01:42 PM
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Here ye, here ye gents..there is certainly a lot of differences of opinion about running the big block pump in a small block. Reading all of the posts I have decided the go ahead a run the STOCK BB pump! I made the decision after one of the gents above stated there is a Moroso part number for a pump shaft that is offered just for this conversion...if Moroso sells parts for this BB pump adaption, then it is OK to do it in my book! Also, my 400 motor will be no lazy day loofer. The cam is out of a ZZ4 and I am going to mildly port the Vortec heads. The thing will have to be putting out over 400 horse power and then some. I really think I need a little more than what a stock oil pump can furnish here and in my opinion and the same for some of your opinions, the stock BB pump is just the ticket without being pricey and going overboard in consuming horsepower. Thanks!
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Old 09-13-2008, 01:46 PM
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Quote:
Originally Posted by dallam11
I'm freshening up my 400SB Chevy with new rings and installing a set of used Vortec heads. Just for insurance, I am going to discard the old oil pump and install a new one. Here's my question...can I install a BB oil pump? If so, do I need a different length intermediate shaft? I like the idea of the big block pump having more gear teeth and producing slightly more oil volume without being much harder to turn than the small block pump....Do you gents agree?
Yeah, I'm a big fan of using the big block pump. It bumps the hot idle and lower RPM oil pressure up which these engines need if they're used hard at low and moderate RPMs or certainly if they are raced where frequent gear changes and high loadings are experienced which is the case on road track and short ovals.

The down side is the big block pump delivers a lot of oil you don't need in the RPM ranges from 3 to 6 thousand so the relief is dumping a lot of unused oil your spending a few horsepower to heat up and dump back in the pan. But I've found this a cost of providing better bearing protection in the lower revs.

Yes you need the shorter intermediate shaft and use a steel rather than plastic coupling.

With the Vortec, GM has had a lot of bottom end warranty issues related to insufficient oiling on hard working engines. I consider the BBC pump and using a 15W40 or 20W-40 oil to be significant insurance against these issues. Especially if you work the engine hard and live in a hot climate.

Bogie
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Old 09-13-2008, 01:47 PM
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Quote:
Originally Posted by curtis73
No, but since the drag on the pump is exponential, (a function of the square of the speed and the pressure based on viscosity) and the pump spins the same speed as the engine (double the cam speed), try spinning that pump to 6000 with some cold 10w40 in the case. Now you've quadrupled the pressure, which (other factors excluded) has multiplied the drag on the pump by at least a factor of 16 - and that is simply from the oil pressure. That doesn't take into consideration the exponential increases in friction on the driveshaft, the drive gear on the cam, and the gerotor friction inside the pump.

People say the same thing about alternators because they spin so freely. Put a load on them and spin them to 5000 rpms and then see how freely they spin.

Oil pumps take considerable HP to run. Otherwise, why would manufacturers use a heat-treated chrome-moly 3/8" shaft to drive it?
Just a side note.
As for people spinning 6000 rpm on cold oil..... yes I have seen a few retards in action. LOL

4000 to 6000 rpm will NOT quadruple the pressure, nor the volume.
Oil pressure is controlled by a spring loaded pop off valve, which controls not only the pressure maximum but the overall volume pumped into the galleries.
Bypassing only reroutes the output to the input side of most of the pumps.

I know that SBC are notorious for poor oil pressure, hoping for at least 10 psi per thousand rpm, but most pumps have pressure springs set around 55 psi. maximum, which "should" be reached well before 5500 rpm. I have seen many that hit 55 psi at 3000 rpm with hot oil.
(Thos of you who have a Ford, yours probably idles with 55 psi hot )

IMO most shafts fatigue and twist off do to harmonic pulsations, not "oil pressure" that somehow? spikes to a million pounds and twists it off.

Dyno tests show that 60 amps draw on an alternator pulls 1 1/2 hp beyond the mechaincal load, which, I do not know how much power it takes to turn an alternator at 5000, do you?

JMO Thanks for the reply.

Last edited by ScoTFrenzel; 09-13-2008 at 01:59 PM.
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Old 09-13-2008, 01:54 PM
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Oil Pressure?

Oil Pressure?

I thought you could just dump 3 1/2 qts oil in and then add two bottles of stp, YIKES!

Heard the best one ever the other day. Checked the oil level on a 4.6 Lincoln, what oil? I added 2 1/2 qts and made sure I told the owner they had such little oil. Response was that for this car, you couldn't add oil until the light came on and then only 1/2 qt. Some men, you just can't reach. Jus blabbin...
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Old 09-13-2008, 01:59 PM
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Quote:
Originally Posted by Stroke
Oil Pressure?

I thought you could just dump 3 1/2 qts oil in and then add two bottles of stp, YIKES!

Heard the best one ever the other day. Checked the oil level on a 4.6 Lincoln, what oil? I added 2 1/2 qts and made sure I told the owner they had such little oil. Response was that for this car, you couldn't add oil until the light came on and then only 1/2 qt. Some men, you just can't reach. Jus blabbin...
Old Amos and Andy line when the station attendant (1950s) showed them the oil level on the dipstick; " Now Amos, who ever done heard of puttin' oil in a new Cadillac".

Bogie
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Old 09-13-2008, 02:07 PM
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I swear======
I put 3 quarts in a Toyota 4 cyl PU years ago just to make it hit the end of the stick....

and he put another 100,000 on the engine after that, and sold the truck still running.
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