Posted by Will (in MI) on Tuesday, October 11, 2005 at 7:59PM :
In Reply to: New Obstacle - PS Pump Belt and Clearances (Radiator Hose / posted by chriscase on Tuesday, October 11, 2005 at 2:50PM :
I got a lot of great ideas, and have looked into all of them, and done a lot of measurements, and investigating. But my direction will likely get a lot of smart comments from some smart guys, but here is my only solution short of moving the PS Pump above the Water Pump.
I'll build a 4" OD PS Pump Pulley that will also move the grove 1/4" closer to the PS Pump. By moving it closer I can move the pump directly against the bracket (removing my 1/4" spacers that I added to align the pulleys), that will also give me additional clearance to the exhaust manifold at the back of the pump, and move the rear bracket forward so it doesn’t hit the valve cover and I can get all of the adjustment travel back. I adjusted the lower radiator hose so that the bend is further back and closer to the frame (1/8" away). With the 4" pulley and the pump at the shortest belt position the belt just clears the hose. You could never install a belt that short, and I may be able to re-adjust the hose for a little more frame clearance when done.
Now for the concern over, overdriving the PS Pump. I measured a stock V grove 318, and the crank pulley is 7", and the PS Pump is 6". The March pulley was stated in the catalog as 6", but actually measures 6-5/8". With a little math, the stock crank pulley going 5,500 RPM would drive the stock PS Pump pulley at 6,417 RPM. With the March under drive crank pulley, and the 4" PS Pump Pulley the same engine sped would increase the PS pump speed by 15%, or to 7,391 RPM. A 4.5" PS Pump pulley would have been almost an exact RMP match, but the belt clearance would be reduce by 1/4".
I might wear out a pump after a few years running it 15% faster, but not many other choices. If I new I could successfully build a metal elbow to replace part of the lower hose, I might go to the 4.5" diameter, but I doubt my welds are leak proof. They've been strong in the past (and hope they still are), but not very pretty.
Thanks for all the help,
Will
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