yes I have a second blower on there now, I understand the other one is toast, my question is how do I prevent it from happening again. Is the hi reving of the rotors causing the heat expansion that is causing the metal rubbing? If so will pulleying down solve the problem?

 

The last two times that I was at Stiegemeier's I examined at least twenty stock Eatons, and all but two had signs of rotor to case contact.

FYI: My Eaton seized with just a 4lb lower.

 

Mostly caused by improper torqueing or possibly removing too much material during porting.

I ran a 2.8" upper and 6lb lower for more than 25k miles with no issues. Blower looked like new when I dissassembled it for inspection. My case was not ported, any time the blower was off I replaced the mounting bolts and torqued them per Ford's spec's. Never had an issue. The bolts are designed to only be torqued once. Perhaps that is also contributing to the problem.

 

looks like an MP or wait on the whipple might do the trick
Did you torque them in the correct sequence and to the correct spec? as you torque the other one down, spin it by hand and see if you are getting contact from the beginning, Mike dunn said he noticed contact as he tighten up the bolts, and as he backed off it would go away.

he ^ beat me to it!

 

what is the torque spec on the blower bolts?

 

There is also a sequence as well. Similar to head bolts.

 

Yep, you start with the 4 middle bolts, then front 2 and finally the 2 in the back of the s/c. Torque them to 18 inch lbs followed by 33ft lbs.

 

I'd like to offer a different theory on the problem......
The rotor pack in the Eaton is about 9 inches long by 6 inches wide. That gives it a surface area of about 54 square inches. At 10 pounds of boost, the pack sees an upward loading of around 540 pounds. At 20 pounds of boost, the load doubles, to about 1080 pounds. Added to that load is the fact that the top of the rotors are seeing partial vacuum. The back of the rotors only have a pair of about 5/8 diameter bearings trying to withstand that load. My feeling is that it is not a matter of how fast you spin them as much as it is how much boost you make that causes the problem. The rotors simply are not rigid enough to withstand the amount of pressure they are seeing. If you have a chance, take a look at the rotors in a 671 blower. They are at least twice the diameter and as such, have a lot more resistance to bending under load.