Rotary rebuild help needed - engine very tight

Looking for anyone with Rotary rebuild experience who might know what's going on with my rebuild.

I just assembled a 12A, and it doesn't spin very freely and gets worse in 3 spots during 1 full engine rotation (3 complete turns of the e-shaft).  The endplay is in spec at .002".  It is making compression on all faces- 6 chugs in 3 rotations of e-shaft.

To get the engine moving takes maybe 10-15ftlbs of torque and to start it turning in the 3 spots where it binds  is like 30-40 ft lbs.  This is with no spark plugs.

I have a low mileage 13bt sitting in my shop, and as a reference it takes about 4 ft lbs to rotate - no binding anywhere.

I have built a few 12A's before, the only things I did differently on this one were 1. glue the corner seals onto the apex seals and 2. use vaseline everywhere instead of a combo of marvel mystery oil, vaseline, and assembly lube.  Did that based on a friend's recommendation plus a you tube video associated with Goopy motorsports.

Here's a rough guide to where the binding happens:

1st bind: pocket of rear rotor face 1 just leaving exhaust port . Call this 0 degrees rotation, stays tight until about 120 degrees rotation.

2nd bind: pocket of rear rotor face 2 is approaching the exhaust port. Binding starts at about 270 degrees, and stays til about 330 degrees.

Then no bind from 330 degrees until about 690 degrees - basically one full rotation with no binding.

3rd bind:  pocket of rear rotor face 3 is leaving the exhaust port.  this starts at about 690 degrees rotation and unbinds about 870 degrees.

Then it's smooth until 1080 degrees (full 3 rotations of e-shaft - rear rotor back to starting position).

It's repeatable - binding happens in the same place in the rotation each time.

Any idea's on what the issue is and/or how to troubleshoot?  Can I un torque the front and rear stationary gears and see if that changes anything?  Can I un torque the tension bolts and see if it frees up?

Thanks,

Neil

In reply to sevenracer :

I assume all the engine components, rotors housings irons, have all been used together as a running engine and therefore none of those are new.

If that is the case I think I would just fire it up and run it. Those torques to turn don't seem to be that high.

Of course if you were not me, and therefore are meticulous, you could disassemble and see if you can find any indication of the reason for the tight spots. 

What is the history of the parts used? Sounds like something is bent; there shouldn't be any "tight" spots. What are you using for apex seals-did you clean their groove thoroughly?

ChasH said:

What is the history of the parts used? Sounds like something is bent; there shouldn't be any "tight" spots. What are you using for apex seals-did you clean their groove thoroughly?

It's all used parts, obviously, the irons were surfaced by a rotary expert, the housings were measured in spec per factory service manual.  This motor has ceramic apex seals.  The one thing I did do was a last minute substitution of the eshaft.  Not sure I measured runoutrunout of the new one, but don't think I've ever run across one out of spec. 

I pulled the stationary gears and there are shiny spots on one side of each bearing. So, it's coming back apart. I think the bearings were going metal to metal when it was binding.

I'll give an update once I can inspect everything.