Chevy Tri Five Forum banner

1 - 13 of 13 Posts

·
Registered
Joined
·
65 Posts
Discussion Starter · #1 ·
I NOTICE THAT WHEN I TAKE MY 55 OUT AND BRING HER BACK IN AND WIPE HER DOWN THAT THERE IS LITTLE SPOTS
OF OIL ON THE BACK BUMPER AND TRUNK LID AND I GET A VERY LITTLE OIL ON MY BREATHER
I HAVE PUT ABOUT A QT. OF OIL IN EVERY 500 TO 700 MILES
I HAVE NOT NOTICE ANY SMOKING OR BLOW BYE
IT DOES HAVE A HIGH VOL. OIL PUMP

1965 327 ENGINE
HUMP HEADS
MILD CAM
WEILAND INTAKE BUD 1
 

·
Registered
Joined
·
166 Posts
The spots on your trunk and bumper could be coming from the engine,trans or rear end.I had a leak in rear end :eek: and it was doing just as you say before I repaired it! :D
 

·
Registered
Joined
·
3,862 Posts
If you have a leak while driving,the vacuum created behind the car will cause the leaking oil to stick to the rear of your car.
Also comes from the exhaust pipes from wet carbon in the pipes and burned oil.
You won't see any smoke until the oil burning gets bad,because the air flow under and over the car dilutes it.Someone following you will see smoke before you see it.
You may have leaking valve stem seals causing this.
Or a bad pcv,if you have one.
Lots of reasons!
Mike.:)
 

·
Registered
Joined
·
36,949 Posts
The HV oil pump is a bad idea, but don't worry about it, it's not your current problem.

ANYTHING that gets oil under your car will show up on the trunk lid, it's just the way these cars are. Could be an oil leak, could be oil from the tailpipes if they extend to the bumper. As 100% said, it's aero. It's even worse on a wagon.
 

·
Registered
Joined
·
36,949 Posts
Oil pump flow rate is determined by engine speed. On a performance engine, you make more power by turning more rpm. More rpm = more oil volume/flow rate. The problem solves itself.

Example: the Moroso wet sump oil pumps are based on a stock volume Chevy oil pump. I've built numerous small block drag race engines that make 650-750 hp and turn 8500-9500 rpm, all built with that stock volume Moroso pump. The Moroso pump actually flows a little less than a stock pump at low rpms because it has mod's that prevent cavitation at high rpm, but those mods just make them leak internally at low rpms.

The only thing the HV pumps do is make it hard to fit the oil pan and related items because they occupy more space.

If your pump is bigger than it needs to be, all the extra volume is just dumped across the pressure relief valve anyway.

And regardless of whether you buy into what I posted above or not, the oil pump volume has nothing to do with oil on the trunk lid.
 

·
Registered
Joined
·
9,469 Posts
Oil pump flow rate is determined by engine speed. On a performance engine, you make more power by turning more rpm. More rpm = more oil volume/flow rate. The problem solves itself.

Example: the Moroso wet sump oil pumps are based on a stock volume Chevy oil pump. I've built numerous small block drag race engines that make 650-750 hp and turn 8500-9500 rpm, all built with that stock volume Moroso pump. The Moroso pump actually flows a little less than a stock pump at low rpms because it has mod's that prevent cavitation at high rpm, but those mods just make them leak internally at low rpms.

The only thing the HV pumps do is make it hard to fit the oil pan and related items because they occupy more space.

If your pump is bigger than it needs to be, all the extra volume is just dumped across the pressure relief valve anyway.

And regardless of whether you buy into what I posted above or not, the oil pump volume has nothing to do with oil on the trunk lid.
Thank you for info Rick.........:)
 

·
Registered
Joined
·
923 Posts
Lots of good points there Rick. I have seen a lot of problems from people using HV oil pumps. I won't put one in a street motor even if the customer insists on it. I don't like them because they flood the top end with oil, on a small block with stock o-ring valve stem seals I have seen them pump enough oil up top to suck it down the valve guides. I run a Big Block stock eliminator car and I use a standard volume small block pump in it. Holds 70 psi. @ 7800 rpm in the lights.
 

·
Registered
Joined
·
2,868 Posts
There are also high pressure oil pumps.

I was looking to install a new oil pump on my '68 327 20 years ago. Off to my local NAPA strore I went. While there and talking to my friend, he explained they carried both. High pressure and high volume oil pumps for small block Chevy engines. This brought some confusion on my part. Which to use?

My friend Doug said in the end, they're probably close as to what they do.

Not being able to decide, I just bought a stock replacement oil pump and went home.
 

·
Registered
Joined
·
3,862 Posts
I just rebuilt my 68,327 and I used a stock pump.
Oil pressure is 30+ at idle,which is good enough for me.
I believe the high pressure/high volume pumps have a finer gear ratio than the stock pumps.
I put the high volume pump in my 454 and it always reads high on the guage.
I used it because I like to use the almost 2 quart filter and thought it could use the higher volume.It did cause the main seal to leak some when new.
Mike.:)
 

·
Registered
Joined
·
36,949 Posts
There are two kinds of high volume pump for a small block.

One has the same case and gears as a standard pump but the gears are longer and the case is lengthened to match. This one is the most common.

The other is essentially a big block pump adapted to a small block. There are more teeth on the big block pump gears. Some people think this is good because there is less "ripple" in the oil pressure. The extra volume is because the gears are bigger in diameter. The case is bigger and this makes it easier to have interference with pan baffles etc.

Either high volume pump needs to have the distance from the pump pickup to the pan bottom checked and adjusted if needed.
 
1 - 13 of 13 Posts
Top