OK so I was wrong:
Finally got the blower totally disassembled ( gears , bearings etc. ) today.
Lots of heat to get the gears lose
..well; loo and behold:
In spite of looking exactly like the first blower on the outside, this is quite different
..as the gears ARE keyed to the shafts
!!! ( unlike the first one that had NO keys )
there are NO oil-seals behind the bearings
the bearings are completely different, being a double-row ball bearing type
with a metal seal/shield towards the blower-body
( and the size: diameter 15mm / outside diam. 35mm / width 23mm (!))
is NOT something I can find at my usual bearing-pusher SIMPLY BEARINGS
the bearing on the pulley side are different as well
being in size that is actually available ( unlike the ones on the first blower)
( The one on the pulley-shaft was shot, maybe from lack of lubrication (?) )
This means that the changed position between the rotors can only
be due to the rotor
(s) having moved in relation to the shaft
The rotors are made of aluminum ( covered with PTFE/"Teflon")
so I take it they are heat-shrink'ed ( is that the term ?) on to the shafts (?).
Maybe you could pin the rotors to the shafts. I recall that being done to the GMC 4-71/6-71 family of blowers to preclude what seemed to happen to your blower, i.e. the rotors slipping on the shaft & then binding.
Before I totally disassembled the darn thing I would have pointed out that
the problem was the gears
were sliding on the shafts
, but obviously I was wrong
so what you say here makes perfect sense.
Split body, must have been quite an object to do the job... I have another supercharger off a twin cylinders Hanomag 2 stroke diesel engine, it's scratted and battered to death but no split, bits normally imbed themselves in the alloy, don't split it??
Patrick. you've got a point, and I think you're right;
It probably wasn't a foreign object .....but ( I must shamefully admit )
the rather spectacular back-fires I experienced before the engine was set-up properly.
We're talking "fire-spitting-through-the-pop-up-valve" BIG-BANG back-fires.
I must ( even more shamefully ) admit that at one point I was suspecting that
the spring on the pop-up valve was too weak, so I added an extra one from
the auto-parts store in Wendover
The back fire theory would somehow explain the altered position of rotors, the splitting of the body and
probably the oil inside the intake as well.
Goodness; I wonder when this happened....maybe I've been riding all along with it
in this condition ?!??
I'm just not too smart.
You live, you make mistakes, you learn.
Gotta get the other blower attached and enjoy how it will now go a LOT faster.
Almost finished working on the heads, filing and sanding and polishing
around the repair.
Wow! It took me a couple of days to get enough time to read the whole thread!
Amazing craftsmanship, and a wonderful story!
Well, THANKS a lot, Flattie !