High volume oil pumps

[hdsadey]

So we have been working on this 383 Chevy airboat engine from Blueprint engines. When I was disassembling it I notice the distributor gear on the HEI had a lot of wear on it! A LOT!!! Further I got and discovered it had a Melling M55HV pump. Now we are requested on a regular basis to install high volume pumps, 99% of the time we refuse. Why? No need for it! High volume pumps are designed to provide extra volume when bearing clearances are opened up more than factory spec. On a engine with proper standard clearances the high volume backs the system up creating high pressure. The pics below show the results of the strain created by this! The gear is severely worn on the heel side of the teeth. Beside the obvious of the shavings of metal through the lubrication system, I believe the ignition would start to retard giving loss of power. We are installing a standard Melling M55 and upgrading the oil pan to a Canton 8 quart to keep up with supply demand at higher revs on this gearbox boat. Cheap insurance in our minds to make sure the pump won't cavitate. Our bearing clearances are .0025 on mains and .0028 on rods. On an engine that won't see 6000, a standard pump is fine with those clearances. Swapping in a hydraulic roller as well since the block is a factory roller, stepping up on size too. New Edelbrock Performer RPM replaces the Blueprint standard Performer. Was a 420hp, should pick up some power with the mods.

If any of you car motor guys need machine work please give us a call at Venice Auto Marine Inc. (VAMI) 941-484-2474. Our new dyno is crated and ready to ship! WOOHOO!!!!!

 

[Slidin Gator]

Now we are requested on a regular basis to install high volume pumps, 99% of the time we refuse. Why? No need for it!

Good move and nice post man, you just laid it out in very simple terms. Motors need oil pressure, but there is definitely such thing as too much. High volume pumps are good for high revving race motors and last ditch efforts to keep a worn out block running for 1 more year. Otherwise all they do is heat up (and wear out) the oil and overload parts.

In my experience if a motor needs a high volume pump the bearings are worn out. I normally opt not to waste time dropping the pan, I just pour in 3 bottles of STP and start planning the swap out after hunt season.

 

[hdsadey]

Pictures of the finished long block. Waiting on some gaskets for the carb, blocking off the power valves and jumping up the jet sizes. It's one of those Summit carbs that looks like the old Autolite 4100 series. Pulled it apart to clean it and discovered the power valves were installed backwards. 6.5 front, 9.5 rear from the specs. Since its a gearbox boat and always under a load the power valves are pretty much canceled out. Opinions? We are waiting to dyno it since it showed lean conditions in all the cylinders, obviously a problem. Want to make sure the tuning correct before going back on the boat!

Notice the Canton 8 quart pan!