sbc oil pump

k-star · Post by **k-star** » Wed Sep 07, 2005 8:00 am

I know this has been discussed before. But not in this exact application..

I am building a 427 sbc. The oil clearance on the rods are all .002 the main oil clearance is .0025 to .0027 The rod side clearance is .022 to .025. it is a hyd roller engine. motown block..

Is there any reason i would need a high volume pump on this engine??? I ask because i have been using standard oil pumps in the last 20 small blocks i built with zero issues. I had a oil pan made just for this application and the manufacturer sent a hv pump along with the pan....

I am thinking about using a standard pump... Any reasons not to???

Keith

CNC BLOCKS · Post by **CNC BLOCKS** » Wed Sep 07, 2005 12:36 pm

k-star wrote:I know this has been discussed before. But not in this exact application..

I am building a 427 sbc. The oil clearance on the rods are all .002 the main oil clearance is .0025 to .0027 The rod side clearance is .022 to .025. it is a hyd roller engine. motown block..

Is there any reason i would need a high volume pump on this engine??? I ask because i have been using standard oil pumps in the last 20 small blocks i built with zero issues. I had a oil pan made just for this application and the manufacturer sent a hv pump along with the pan....

I am thinking about using a standard pump... Any reasons not to???

Keith

We have always used the standard volume pump with high pressue spring with no issues for years and plenty of oil pressure.

Side clearance does not really factor into the equation as the the bearing clearances dictate oil flow or resistance. If this was true the piston guided rod engines we have work on with over .090 side clearance would be running zero pressure.

SupStk · Post by **SupStk** » Wed Sep 07, 2005 2:47 pm

I agree with Carl. My 350 SBC drag car runs with reduced volume and pressure (cut stock pump with a stuffer plate and 35PSI @ 8,000) with no bearing issues. I'd never get away with this on a customer engine, some traditions die hard.

SStrokerAce · Post by **SStrokerAce** » Wed Sep 07, 2005 3:47 pm

I would vote on the standard volume setup as well. If you went to a high volume setup I would set the pressure spring in the 50psi range and run a lighter oil since you are going to have some awesome oil pressure when cold.

I run std volume pumps on all NA hyd roller street motors seeing 7500rpm or less. Obviously from SupStk's comments you don't need any more than that if you spin it higher.

Bret

SupStk · Post by **SupStk** » Wed Sep 07, 2005 3:56 pm

Keith, Let me qualify my earlier post. If you are running a cross drilled crank by all means put in a high pressure/ volume pump. Those things are like a giant hemmorage inside the engine and it takes alot of oil to keep the bearings happy.

CNC BLOCKS · Post by **CNC BLOCKS** » Fri Sep 09, 2005 12:12 pm

CNC BLOCKS wrote:
k-star wrote:I know this has been discussed before. But not in this exact application..

I am building a 427 sbc. The oil clearance on the rods are all .002 the main oil clearance is .0025 to .0027 The rod side clearance is .022 to .025. it is a hyd roller engine. motown block..

Is there any reason i would need a high volume pump on this engine??? I ask because i have been using standard oil pumps in the last 20 small blocks i built with zero issues. I had a oil pan made just for this application and the manufacturer sent a hv pump along with the pan....

I am thinking about using a standard pump... Any reasons not to???

Keith
We have always used the standard volume pump with high pressue spring with no issues for years and plenty of oil pressure.

Side clearance does not really factor into the equation as the the bearing clearances dictate oil flow or resistance. If this was true the piston guided rod engines we have work on with over .090 side clearance would be running zero pressure.

Sorry I misread the post as I thought is was a BBC and now I see its a 427 SBC as I would use the M-55HV as on those pump we rework the pump and machine an extra bypass hole in the cover and shorten the plunger about .080 and seems to work fine for us.

k-star · Post by **k-star** » Fri Sep 09, 2005 1:32 pm

Ok i guess i'll use the hv pump... It does have a cross drilled crank also..

Carl what do you do to modify the pump???? Do you just shim the plunger to loose the .080" ???? where do you drill the extra by-pass hole....

Keith

SStrokerAce · Post by **SStrokerAce** » Fri Sep 09, 2005 2:02 pm

I'm gonna guess that the extra bypass hole is a continuation on the bypass into the intake, but instead of stopping the cross hole in the bypass/spring hole you cross thru that. Therefore when you bleed off extra oil it bypasses out into the pan rather than back into the pump intake. This would cut down areation of the oil.

Bret

CNC BLOCKS · Post by **CNC BLOCKS** » Fri Sep 09, 2005 10:39 pm

SStrokerAce wrote:I'm gonna guess that the extra bypass hole is a continuation on the bypass into the intake, but instead of stopping the cross hole in the bypass/spring hole you cross thru that. Therefore when you bleed off extra oil it bypasses out into the pan rather than back into the pump intake. This would cut down areation of the oil.

Bret

Your right and we see less high pressures when the engines are cold and the dist. gears look a lot better.

We cut the plunger back to expose more of the bypass hole that drilled in the cover so the punger will come back more with out hitting the pin.

SStrokerAce · Post by **SStrokerAce** » Sat Sep 10, 2005 2:49 am

Thanks Carl... I like that idea as well.

Have you plugged the bypass hole that goes back into the intake all together with a set screw or something? I'm just thinking about getting rid of as much aeration of the oil as possible for hyd lifter applications.

Bret

CNC BLOCKS · Post by **CNC BLOCKS** » Sat Sep 10, 2005 6:48 am

SStrokerAce wrote:Thanks Carl... I like that idea as well.

Have you plugged the bypass hole that goes back into the intake all together with a set screw or something? I'm just thinking about getting rid of as much aeration of the oil as possible for hyd lifter applications.

Bret

Bret

Nothing but just adding an extra bypass hole and shorten the plunger.

SStrokerAce · Post by **SStrokerAce** » Sat Sep 10, 2005 10:59 pm

How much do you shorten the plunger? The bypass hole is easy.... you just don't want the plunger too short because you could uncover the hole outlet hole correct?

Bret

CNC BLOCKS · Post by **CNC BLOCKS** » Sun Sep 11, 2005 12:28 am

SStrokerAce wrote:How much do you shorten the plunger? The bypass hole is easy.... you just don't want the plunger too short because you could uncover the hole outlet hole correct?

Bret

Yes I shorten it around .080 seem to work for me,

SStrokerAce · Post by **SStrokerAce** » Mon Sep 12, 2005 2:14 am

Yeah I didn't think you would want a ton off of it. I've found the limit to the plunger travel for me can be the spring coil bind length since I usually just make a shim to get the pressure where I wanted it. If you take too much off and uncover either bypass hole the pump will have less or no suction thru the pickup so that's about usless.

Good conversion Carl, thanks.

Bret

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