Oil Pump differences

[mingo]

I have a 2.8L out of a 86 Camaro that i was rebuilding with a 1/2" oil pump pick up tube. My machine shop had a GM 3.1L out of a Isuzu Rodeo that they completely rebuilt and the owner never came back for it. I got it at a smoking deal along with a complete gasket set and new oil pump with out the pick up tube/screen. When transfering all my stuff from the 2.8L to the 3.1L the new oil pump for the 3.1 provided by the machine shop has a 3/4" pick up tube.

Will the 3.1L Isuzu oil pump pick up tube/screen work with my Camaro oil pan? Or should I just put on the smaller 1/2" that came off the camaro 2.8L. Does the larger oil pump (3.1L) provide better oiling than the smaller (2.8L) pump. or is there no difference other than the pick up tube size?

Just FYI this is being installed in a 71 MGB roadster.

[60dgrzbelow0]

Okay... there might be a few ways to solve this problem. Lets examine your options:

1. Transfer all of your existing hardware from the 2.8L engine over to to the 3,1L motor, mindiful of course of the critical differences in the pistons/quench/head choice issues that you have not touched upon. Then, use the original 86' Chevrolet Camaro 2.8L Oil Pan and after disassembling and inspecting your original 2.8L Oil Pump for excessive gear wear, thrust plate wear or any obvious damage to the pump body (MAKE DAMNED CERTAIN TO PUT A MAGNET ON THE OLDER 2.8L PUMP...SOME WERE MADE OF ALUMINUM BACK IN THE 1980s...IF THE MAGNET DOES NOT STICK...SH*TCAN THAT OIL PUMP!!!)... If it turns out to made of heavy Cast Iron...move on to modifying that pump to increase its Oil Pressure by using the GM Part # 10044435 Oil Pressure Control Spring in place of the stock one and this should ensure you have adequite oil pressure with the higher power engine. This arrangement would eliminate the problem of not being able to match the 1/2" Oil Pick Up Tube with the newer, more robust 3/4" Pick Up Tube featured on the GM 3.4L L-32 Engine via the Melling Model # M134 OEM Replacement Oil Pump. Don't be tempted to "shim" your existing spring in the old pump as they have a finite number of compressions and releases before they fail...and contrary to popular belief that these little springs only rarely have to open... they are busy as hell trying to keep excessive oil pressure at much higher RPM from bursting the oil filter seal...or worse...rupturing the metal cannister portion under too much pressure. The New, Stronger Spring will allow the oil pressure to build a bit higher. What you need to keep in mind is that the oiling requirements of your new motor will be somewhat higher on the volume end and you really need to get this issue nailed correctly. Too little pickup via that narrow 1/2" tube and screen placed 1/4" above the bottom of the pan...and at higher RPM, the engine will starve for oil...and with "Too Much Oil Pump" such as the Melling High Volume Oil Pump...and you will wind up pumping too much oil out of the crank case up into the top end of the motor...or the engine block relief valve will simply open and dump off the oil if the pressures get too hectic ...volume-wise.

2. You might consider this before you have the New GM 3.1L V6 Engine "Shoe-Horned" into the little engine nacelle of the MGB and figure out if you can swap over to the 4th Gen F-Body Camaro-Firebird Oil Pan-Melling M134 Oil Pump Set-Up as the right combination to choose. If that Oil Pan will fit... then you just need to get a new 3/4" Oil Pickup Tube and follow "Melling's Proper Height for Oil Screens Install Video" for how to do this without making the job FUBAR and lunching the motor if you get things wrong. This film is very instructive:

http://www.youtube.com/watch?v=KOIhaI3eEog

And here is the data, specs and image of the Melling Bare Pump (NO SCREENs COME WITH THESE PUMPS!)

http://www.northernautoparts.com/ProductModelDetail.cfm?ProductModelId=16229

DON'T FORGET TO PRIME THAT OIL PUMP AND THE MOTOR....TOOOOOO!!!

http://www.youtube.com/watch?v=tOYLlr8uQ8k&feature=related

One last thing...don't get too creative and try to either neck-up or neck-down either of these pump/pick-up tube combinations. They might wind up working well enough for you to start the engine and idle around a bit...but with a mismatch of this order...you could cause the bigger (or smaller?) Oil Pump to cavitate and fail at higher RPM.

[mingo]

Appreciate the info. I ordered the 3/4 pick up screen and watched the videos last night. The Mellings M134 is the pump that the machine shop supplied. I plan on getting the motor all set up on a bench stand and run it out too make sure of no leaks and proper tune before stabbing it into the MGB. I have plenty of time and dont plan on the swap until next fall. The Driving season is coming and dont want to look at my car all summer. I want to drive it. Again, Thanks for you input.

[geoffinbc]

Use the 3.1L pump. Just keep the standard volume and pressure pump. It is actually a larger capacity than the 2.8L pump so your all set. Just get the right pickup tube. When you set the depth it is a good idea to tack the pickup tube to the pump body so it cannot come loose.