Hi, I'm pulling my engine out to install a new set of heads, bigger road race oil pan & a baby solid roller cam........what oil pump should I use? The bottom end is a stock low mile 85 corvette 4 bolt main block. My Electrical gauge reads about 20 @ idle now. Thanks!

 

Stock pump is fine for ANY street driven car. Don't listen to Bubba.

 

Agreed. Al

 

a stock pump or a melling are both excellent

 

What lifters are you using with that solid roller? There are several different sizes of pressurized oilers to the axles (which is a good idea for the street). These style lifters create an *internal leak* that the oil pump will have to outrun. Again, there are different sized orifices..some have almost no effect on idle/low RPM pressure...some can knock off 5-10 psi. In those cases a high volume pump can be handy as well as if you happen to open clearances elsewhere.

I'm assuming with a solid roller and road race pan you're planning on some RPM....hope the bottom end is up to all the new work!


I agree a stock pump can do everything you need...but I'd use the Z-28/High pressure spring to kick it up a little at the the top end if you're going to lean on it hard. There are lots of 9000+ RPM engines crossing the line at 40 psi...but those are very precision built engines with high $$$ oil that is changed every few runs and have elaborate scienced out oiling systems.

JIM

 

The melling HV is always a piece of mind! I've seen to many spun bearings on road racers because their engines got hot and oil pressure went south!
Even though it might cost you 4 or 5 HP , you'll never fell it


Be sure you match you pick up 1/4 from the bottom of your new pan and always tack weld the pick up or get the pick up retainer bracket. For a few more dollars, get the HD oil drive shaft with the steel collar.

The Bubba squad might say no but they usually don't beat the crap out of their cars like we do and they also have the bucks to build new engines instead of piecing together someone else's used engine on a budget. For $35 , I'll take the HV High Volume every time!!!

 

I'll get the part number at work. It came as part of the kit. I was told by a engine builder friend to get a bigger pan, I didn't think to ask him about the pump.

I was initially worried about the lifters, but where I live & how I drive, I never idle! If I see a stack of traffic, I take a different road. Kinda nice to live in the sticks!

If I'm to believe the previous owner, which I have no reason not to, I have a little over 2K on the engine. I have no plans on running it to 6500 RPM's regularly. I wanted a nice running, mild street 350 & this seemed to be the cam that kept winning average HP & Torque.

If the motor pukes.....eh, I didn't have much in it & I'll get something built more solid.

 

I'll take that under advisement & Yes, I will make sure about the pick up. Thanks.

 

I used the Melling upgrade kit plus the higher pressure spring. My pressure is now about 60psi all the time.

 

If you're not zinging past 6500 a lot....certainly a good hyd Roller cam with GOOD Lifters can do what you need.

JIM

 

One recommendation I will make is to braze the pickup to the oil pump. If the pickup falls out due to vibration, you’ll have to pull the pan down again to correct.

While any good oil pump will work, you may want to consider an oil accumulator like accusump. The advantage to pre-oil is also an advantage.

 

Thanks for providing a reference on why NOT to use an HP/HV pump.

 

I recently went through the same dilemma you are facing with respect to selecting your pump. When I was trolling through the myriad of postings and strong opinions on both sides of the Higher Pressure, higher volume debate I came across a link which helped me make my decision. It's at the bottom of the post for you if you want to follow.

General consensus is that 10lbs/1000 rpm is really a sweet spot for the SBC and most engines. Any less is too low, and any more is wasted energy. The key is getting the right pressure at the right rpm. That last part is important as the volume of oil is just as important as the pressure.

Remember, the oiling system has a pressure relief spring which acts as an upper limit for the pressure at the pump. Any more than that level of pressure, and it dumps the oil into the bypass, not to your bearings.

Secondly, the volume of oil is important, you want to make sure you are getting enough oil at the right pressure to shield the bearing surfaces and support the load. Too little volume and the oil film will not be sufficient to do this.

If you ramp pressure too quickly, you will hit the bypass too soon and the volume of oil is limited to the bearings where you want it to be. If you pump too much volume without having larger bearing tolerances to allow it to escape quickly, you will increase the pressure in the system as well (see Boyle's law), bringing the bypass into play again. decreasing the amount of useful oil preventing wear.

The key then is to find a balance that allows you to have the right pressure for the motor at the right rpm. This seems a bit counter-intuitive as we all seem to think that we should develop the maximum oil pressure shortly after idle and that pressure at idle is some kind of indication of how good the oiling system is. I personally don't believe this is the case.

The perfect system would develop enough pressure at idle, and then scale as close to the magic 10lbs/1K rpm as the engine accelerates. This would ensure that you have enough oil pressure to provide adequate protection, AND that the volume of oil increases in conjunction with RPMs (because you haven't hit the bypass). So, it is reasonable to have a system that idles around 20 or so lbs, and then ramps as we accelerate. In fact, it is preferable and most efficient (why bother wasting HP pumping oil on a round trip through the pump and then through the bypass?). If you redline at 7K rpm, you should have a system that develops 70 psi around that rpm.

There is a third variable that can be adjusted to try and hit the magic mark, oil viscosity. The link below goes through some very good fact-based discussions on why the manufacturers recommendations aren't really that good, and you should tune your oil to your motor and application. I really would suggest spending the time reading it. Though quite lengthy, I found it fascinating.

Good luck with your choice. Me, personally I ended up with a Melling Select pump (for the stronger housing at higher RPM) using standard pressure and volume.

http://ferrarichat.com/forum/faq.php...tor_oil_basics

 

Just because a pump goes over relief does NOT mean that the flow to the bearings is reduced, it is not reduced.
Stock sbc pumps relieved at 50psi, Z28 and HV aftermarket pumps generally at 70psi.
Gm allows as little as 5psi at idle, it's in their specs.
The assumption that 10psi/1000rpm assumes that the relationship for pressure is linear, it's not. It's just something that is widely spread statement, but good enough to live by.

Pretty simple to understand if you are over relief, if your pressure is less than the relief spring pressure, the pump is not bypassing.
Higher mileage engines can use HV pumps to advantage, for absolute lubrication and just as important, cooling. I would rather have lower viscosity, higher volume and flow, lower pressure and better cooling.
Keep in mind the oil pump is the only assembly that uses unfiltered oil. They do wear.

Do you absolutely need a hv pump, probably not, if you do some lubrication mods, it can be necessary. GM at least thought that a higher psi pump was needed in some applications. Some Ford engines were at 125psi.
And to say that millions of small blocks didn't need better oiling means absolutely nothing, millions also puked before 100,000 miles.