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GO TO Protek Performance THE RV-7 AIRCRAFT BUILDING THE KIT e-mail: robert@protekperformance.com
OTHER USEFUL SITES Project started 8/15/01
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Checking Supercharger Alignment 10-15-03 The alignment of the supercharger belt pulleys has turned out to be more finicky than planned. I have come up with a tool to check the pulley alignment with pretty good accuracy. As a result I have made a modification to the supercharger mount to acheive better pulley alignment. To be thorough, the supercharger pulley alignment should be checked in all three axes. I have made a simple Sight Plate to check two axes. The third axis can be checked with a 3' piece of drill rod or other stiff and straight material. Below is a picture of the Sight Plate. This is simply a piece of flat 0.040" aluminum with a half round cut out in one side. 
The cut out in the Sight Plate is sized such that the cut out will slide into one of the supercharger pulley belt grooves as shown below. The Sight Plate should fit tightly into the groove such that the groove firmly establishes the orientation of the plate 
Once the Sight Plate has been installed onto the supercharger pulley, it is possible to look down the belt runs, top and bottom, looking from the crank pulley side of the belt toward the supercharger. You can vividly see the belt plane established by the Sight Plate and see whether or not the installed belt and crankshaft pulley are in the same plane. If they are not, then a supercharger mounting adjustment is required. There are two things to look for when using the Sight Plate. First, look at whether the top run of the belt has the same alignment as the bottom run of the belt. This will tell you if the forward end of the supercharger is at the correct installed height on the pivot bracket. Second, look to see if the Sight Plate, top and bottom together point in line with the belt, or if the Plate points to far forward or aft. This requires a shim under the forward or rear pivot mounting bolt to correct. Make sure to do all alignment checks with a tensioned belt installed. 
In my case, I needed to raise the forward end of the supercharger by 0.075" to align the pulleys. After this, I did not require a shim under either pivot bolt for further alignment. I acheived the adjustment on the forward pivot bolt by machining the countersink in the pivot bracket up the required distance and welding the pivot bracket bolt head to the pivot bracket at this position. 
The third axis of alignment is to check that the supercharger is in the correct fore to aft position. This can be done by holding a straight edge to the face of the crankshaft pulley along both top and bottom runs of the supercharger belt to make sure that the belt does not angle fore or aft as it leaves the large pulley and goes to the small pulley. Only use the highest quality belt for the supercharger. Do not use a rubber serpentine belt. These are fragile in construction. Use a poly belt such as Goodyear Gatorback series, part no. 4060550. This is a six groove, 55 inch belt. |