TOONAH
15+ Year Contributor
- 170
- 2
- Jan 14, 2008
-
Madison,
Wisconsin
I have read the suggested threads and have studied the VFAQS regarding the BS elimination stubby shaft, but because of its importance I think all future 4G63 builders need a clear answer to this question. The kits sold on EBay and by Parts Dinosaur are usually the PCI kit or one with the same non-grooved stubby shaft. The Mitsubishi stubby shaft duplicates the actual balance shaft oil pump gear end by machining a chamfered groove around the stubby shaft's circumference about three fifths of the distance back from the gear end. Now that groove is there either to fascilitate the flow of oil into the lateral hole inside the shaft that supplies oil to the bearing further back in the block or to actually permit more oil to lubricate the shaft at the gear end. Some posts I have read claim that the PCI type stubby shaft can sieze up due to lack of lubrication at high RPM's.
This is not good of course, the whole motor could be trashed. In the instructions I recieved
with my kit, it explicitly asks that the clearance of the shaft O.D. and the reciever hole in the pump be at least 5-6thousandths. This I assumed was to assure proper lubrication.
I could see no way of actually measuring the clearance. Could not plastigauge it, no feeler would fit into it. So I said to myself, "it spins freely and has a minute amount of play so its got to be OK". At that time I did not realize that the Mitsu stubby had a groove in it.
Now I am worried. Should I tear my motor (still on engine stand) back down, and replace it with the Mitsu stubby or not? This is my second 4G63 build but I still have not fired up my other 6 bolt engine yet either. I am rebuilding two DSM's. One for my kid and one for me!!!
If any of you have had problems with oil pump destruction due to stubby shafts please reply to this post. I have a wad of dough into these cars.
This is not good of course, the whole motor could be trashed. In the instructions I recieved
with my kit, it explicitly asks that the clearance of the shaft O.D. and the reciever hole in the pump be at least 5-6thousandths. This I assumed was to assure proper lubrication.
I could see no way of actually measuring the clearance. Could not plastigauge it, no feeler would fit into it. So I said to myself, "it spins freely and has a minute amount of play so its got to be OK". At that time I did not realize that the Mitsu stubby had a groove in it.
Now I am worried. Should I tear my motor (still on engine stand) back down, and replace it with the Mitsu stubby or not? This is my second 4G63 build but I still have not fired up my other 6 bolt engine yet either. I am rebuilding two DSM's. One for my kid and one for me!!!
If any of you have had problems with oil pump destruction due to stubby shafts please reply to this post. I have a wad of dough into these cars.
