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I've got my motor mounts built, and tack welded in place. the position seems good, level side to side. the mounts are level with the top of the frame. my question is how much is the angle from front to back? How much lower than the engine should the tranny be? How much pinion angle on the rear end? Thanks in advance./

The general rule of thumb is that the line of the engine crankshaft and the line of the rear axle input need to be parallel. That doesn't mean you need a straight line from crankshaft through axle; only that the angle at both U joints is roughly the same.

Easiest way is to get a magnetic angle measuring device (Harbor Freight, etc.) and make sure the clutch plate and axle input have the same angle.

This should be measured fully loaded: cab and engine installed (or weighted down with some bags of concrete, etc.) and wheels on the ground. I'd guess you'd put the engine in place, then shim the axle to fit.

If the angles are too different you will get vibrations - unlike CV (constant velocity) joints, U-joints spinning velocity changes as it spins faster and slower. If the angles are mismatched then the axle input is driven faster then slower even with a constant crankshaft speed. This obviously wears parts down quickly.

Now the tricky part...under acceleration the axle will rotate. Some folks put a few degrees of angle into the axle to compensate for acceleration...3 degrees springs to mind. This is probably more of a concern for the drag racers out there...

-Boyo

One final note - I had a clearance problem between the main pulley and the frame, and the fan and the radiator. Make sure you've test fitted the radiator and pulleys in the engine before locking it down...

-Boyo

When I put the 235 in my '37 I angled the back end of the motor down until the carburetor sat level(if the motor is level, the carb is tilted forward). As was mentioned above, the tranny output shaft should be parallel to the pinion shaft. This way the two u-joints compensate for each other eliminating vibration.

I know I asked the same question when I put my motor in also. I was told the angle of the pinion and drive shaft should be no more than 3 deg, pinion being lower, this will cover any twist in the axle on start up from stops. For the engine I did like Eric did. I put a SBC 350 in my '46 1/2 ton Panel and set a small bullet level on the intake/carb mount and set it level. Thats how I was told to do it and it worked out great.

Teachings I took from a class tauht by Eaton. At least 1/2degr. to no more than 3degr. of angle , you must have the 1/2degr. to keep the needle rolling in the cup