Your project is a pleasure to follow. The photography is outstanding and your work is artfull. I'm going to miss this thread when you are done.
Thanks Harvey !!!
I'd like to make some comments on your supercharger. First is the translation of the type of gears that drive the rotors. The mechanics here call them helical. Bevel cut gears allow the direction of the shafts to angle in a different direction (most commonally 90 degrees).
Sorry. You're you're right. Thanks for pointing it out.
As you may know: English is not my mother tongue
and some times I mix up all these technical terms.
It looks like one of the gears is keyed on the rotor. The other one must be a interference fit on the shaft? I have only worked on the Roots type blowers that were used on Detroit Diesels. Both rotors were keyed to the rotors and were adjusted (timed) by moving the gear in or out on the shaft which turns the shaft (lobes) in relation to the the other shaft (lobes). The movement of the gear is positioned by shims ( I think I saw shims in your picture of blower parts). I believe the shims were placed between the bearing and the blower case. This is the accurate way to adjust the lobe clearance easily.
I understand well what you're saying about shimming (in effect moving the one gear(-->shaft-->lobe) is relation to the other
but I'm afraid it doesn't apply to this here blower.
It's actually very crudely put together and apparently consist of parts that must have been
originally made for some other application, and then used for this thing, probably to save
of the helical gears do have a provision (key-slot(?)) for a woodruff key
but the shaft does not
..both shafts have a thread ("outside" the gears) but only one (!) of them has a nut to go on the thread
So there is no way to 'adjust' by shimming , the lobe clearance.
One just have to get it right when assembling.
It's little difficult to explain but, I can try:
the 'shims' you see on the photo (at the pulley-end) are used at the other end of the blower
to hold the bearings at the right position in relation to the 'neck' on the shaft
and the body of the blower.
The clearances were checked by long feeler gauges through the discharge port. You probably don't have any specifications on the clearances but the clearances should be checked both ways with a slight drag on the driven rotor. If you could find a repair manual on a Detroit diesel 3 cylinder/ 51 series engine it may give you some information that would help. It would seem if the clearances were tighter at the discharge area it would pump more pressure. If you would like, I can look for some information here.
... no I don't have any spec's, just checked for even clearance with a feeler gauge
and I have been in contact with another guy who's been rebuilding one of them here thingies
and listened to his experiences.