Thread: 383 oil issues

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In my opinion, Jerry nailed it. The motor is running itself out of oil.
Sling the HV pump over the fence and install a standard M55 pump. It's all the pump the motor will need. Set the pickup at 3/8" to 1/2" off the floor of the pan, using modeling clay to find the clearance. Make an ice-cream-shaped lump of clay and smush it onto the bottom of the pickup, then trial fit the pan, observing the length of the clay. Any closer than 3/8" to 1/2" may allow the pump pickup to suck down against the bottom of the pan and shut off supply to the pump. Any farther away than that will leave oil in the bottom of the pan that should be moving around the motor.

Some fellows will use Play-Dough for finding the clearance. I like to use oil-based modeling clay from the crafts store.

Originally Posted by techinspector1

In my opinion, Jerry nailed it. The motor is running itself out of oil.

"I do agree, that is exactly what it acts like."

Sling the HV pump over the fence and install a standard M55 pump. It's all the pump the motor will need. Set the pickup at 3/8" to 1/2" off the floor of the pan, using modeling clay to find the clearance. Make an ice-cream-shaped lump of clay and smush it onto the bottom of the pickup, then trial fit the pan, observing the length of the clay. Any closer than 3/8" to 1/2" may allow the pump pickup to suck down against the bottom of the pan and shut off supply to the pump. Any farther away than that will leave oil in the bottom of the pan that should be moving around the motor.

Some fellows will use Play-Dough for finding the clearance. I like to use oil-based modeling clay from the crafts store.

Yes.. have clay I keep in the fridge for that purpose. On an OEM pump pickup the shaped bottom of the pickup precludes it from "totally" being blocked off.. onlike the flat pickup it did have in it. It can still cause a problem if there is gunk in the bottom of the pan...
From taking pumps apart, the only main difference I can see between the m55hv and the m55 is the pressure spring. You can take a set of stock vanes from a GM pump and slide them right into either Melling pump. I have often wondered HOW they can call it a HV pump if it has the same amount of vanes in the impeller.. I use the HV because of the higher pressure it delivers. this engine will run 8k rpm on a regular basis, but blocking a stock GM pump, grinding a groove for cavitation and putting a white spring in it would serve the same purpose, but the price of the melling pumps makes the labor or modifying a pump like we used to do not worthwhile.
Going to go drop off another block to have it bored Monday. When i get it back I'll transfer this rotating assembly, heads etc to it, and then have this block checked. If I, or one of you guys dont come up with a brainstorm before then. Reaching the end of my rope... Wife always did say my rope was short...