Ed, I just measured my used (slots not yet thoroughly cleaned) rotors and the slots are 1.86 and are uniform from top to bottom. From now on this will be a critical measurement when assessing engine condition. Jerry


On Thursday, April 14, 2005, at 02:51 PM, Ed Anderson wrote:

Well, I continue to gather more information on the seal failure.  I measured the apex seal slot width at it bottom (where you would expect little wear) and at its top.  These are the results on the "good" rotor, I didn't bother with the "bad" rotor.
 
Apex Location            Base            Top
 
Seal1                        1.99mm        2.16 - 2.26mm
Seal2                        1.98mm        2.22 - 2.25mm
Seal3                        1.98mm        2.18 - 2.20mm
 
Clearly the slot is larger at the top - is this due to design or is this due to wear?  Lynn??? Anybody?
 
In any case I found the specs for the space left between seal and slot side after you stick an Apex seal in the slot, again in the good rotor (I used a new seal), the max limit permitted (specs) is 0.15mm,  ALL the slots would accept a 0.15mm leaf gauge blade between the seal and top of the apex slot and some would accept a 0.18mm blade.  Clearly at or outside the max limits.
 
As I rotated the rotors around their housings before I completely disassembled the engine, I noticed that the apex seals seemed to be leaning quite a bit as they brushed along the housing walls.  I think these measurements indicate I either got a rotor set  that was on its last legs or something cause abnormal wear.  Since the rotors were used, I have no ideal how many miles or how hard the miles may have been.  I have read that apex slots can become worn sufficiently that the apex seal will fold over the edge - and a piece of one apex seal certainly did.
 
The question is did it fold over due to a foreign object first breaking the seal or did the seal break because its center section was encountering increased drag and bending motion compared to its ends?  The ends stayed in place.
 
  Upon closer examination it appears there are faint  "chatter" marks on the inside of the rotor housings, you can see them visually and when I move my fingers over them I can detect a very faint variation like a wave pattern.   The rotors were used also and  I certainly don't recall after 4 years - but they could have been present then.  Fortunately, I do have a set of practically brand new rotor housings - although they are not turbo housings - well, the plus side may be easier to muffler {:>)
 
At this point I am inclined toward new rotors to h___l with the expense.  I'm going to get hemorrhoids if this keeps up {:>). 
 
Just though you would like to know.
 
Ed
 
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com