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Meat Popsicle
2,919 Posts
Discussion Starter #1
I know I've posted about this before but I was hoping to get some input from you guys before I send the blower off to have it rebuilt.

So here it goes...

A while back, I had Stiegemeier rebuild one of my M45's. The bearings were bad and I wanted to have it ported. Well, Stieg ended up putting the rotors on a lathe (even though I didn't ask them to) in order to take some of the scratches/gouges out of the edges. Of course, this increased the clearances and allowed some boost to leak-by. So now, instead of 11psi, I'm making between 5-7 progressively as the RPM's build.

Luckily, I had another M45 which is in very good condition so I decided to take some measurements. I measured the clearance between the rotors and the bottom of the case as follows:

Known good blower:

Rotor-to-case clearance = .005"

Problematic blower:

Rotor-to-case clearance = .008"

I measured both rotors in similar positions and the measurements were pretty much identical on either side. Unfortunately, there wasn't really a way to measure in any other position. Measuring the rotor-to-rotor clearance is nearly impossible, even with the rotor assembly removed from the case since it's a curved surface.

So OK, we have an extra .003". That can be corrected by coating the rotors which i plan on having done soon by Embree Machine.

Here's the thing I'm not too sure about. The right rotor on the 'bad' blower has some vertical play in it. The feeler gauge will force the rotor upwards maybe .002" when I'm measuring. I can move it up and down with my finger and although I can't physically feel the movement, I can hear it. I can also hold the blower upright and shake it back and forth and I hear the movement. So I'm wondering, what could cause this play in the rotor?

I'm assuming its' the bearing...can't imagine what else it could be. Any thoughts?
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