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Author Topic:   Rear main situation
posted July 03, 2000 05:55 PM
So far this season two of our three 406s have
had the oil pump break in two in the center of the neck and the rear main cap split in across the center.
One engine had a Melling pump, the other broke last night with a pump from Moroso. Both are wet sump engines with G.M. cranks, Childs & Albert rods, Ross flat top pistons and Vortec heads. The better one is 12.9:1 and turns 6500 the back up motor is 12.5:1 and runs best at 6000. Both engines over the last couple years have won many races and track championships all the sudden two breakages like this inside of 4 weeks of each other.

posted July 05, 2000 04:09 PM
LEDD, It sounds like the problem is not in the motor.But in the components that bolt on, did you use the same distributer?? Is that bent???? How about the input shaft of the tranny??????? ALL this assumes that you
have not run over a rock pile with both motors in the car. And all clearances are right inside the motors.........
Did you take the pumps apart to see which direction the force came from that broke the pump????? How about a balance plate on the rear of the motor, is that on right. I'm not trying to make you look stupid, I'm just trying to help. Everyone have put some thing together wrong when they where in a hurry, then the next time they take it apart they pay attention to the way it comes apart. Problem being that its together wrong so then it get puts together wrong for a second time...........
What have you changed in the car from last many nights of racing did these motors have before they broke???
give some more information and i'll see what else i can come up with..........JEFF

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