|
No Georges, no tools missing - had not done any work on the engine for a
number of flights. Nothing of a "diamond" shape has come to mind either
{:>).
Beware! the fact that a seal slot is worn will not keep you from
having compression, if the seal is still being pressed against the rotor
housing. So that is not necessarily a good test of slot wear -
the problem is slot wear changes the magnitude and angle of forces
mix acting on the apex seal. If they get to a certain point, they can
fracture the rather brittle apex seal.
I am fairly certain that the wear limits on the slots specified by
Mazda are there for a good reason. If the seals are approx 1.91 mm wide and the
bottom of the slots appear to be around 1.98 wide then the new seal in the new
slot have a clearance of about 1.98 - 1.91 = 0.07 mm. And as you can see
from the specs taken from the Mazda workshop manual that is well within the
standard (near the lower end). To stay with the maximum Limit spec
(0.15mm) the slot should be no wider than 1.91 + 0.15 = 2.06mm. So when
you have slots measuring 2.16 to 2.43 mm wide, its clear to me
that they are WAY beyond the limit. You of course can choose to
accept that and perhaps for an auto I would as well - but not me - not for an
aircraft use.
|
Clearance of apex seal and rotor groove |
|
|
Standard |
0.0024 to 0.004 in (0.062 to 0.102mm) |
|
Limit |
0.006 in (0.15mm) |
Of course, apex seals won't
cause the engine to smoke, bad oil seal/rings will. But, I assume
you mentioned that as an indication of the good condition the engine was
in. It may be running well now, but the question is how much
longer would it have run. In auto use perhaps for quite a spell - in
aircraft use perhaps less, who knows for certain?
I clearly do not have decades of rotary engine experience, but I do believe
that the engine manufacture probably has good reason for limits in
specifications. If you are near, but within the limits you
should be OK, but when you get way past the limit then you are on borrowed time
as they say. Just my opinion of course.
One of the reason I am going with Tracy Crooks apex seals is to get a much
stronger, non-brittle seal. I saw a big man try to break one of Tracy's
seals by pressing it against the corner of a table and using his weight to break
the seal. A normal stock seal you can break with your hands (use gloves if
trying) but after apply all his weight several times it began to bend and
finally broke - but it was an impressive display of how strong those seals
were.
Ed A
----- Original Message -----
Sent: Monday, April 18, 2005 1:10
AM
Subject: [FlyRotary] Re: New rotors, New
housings
|
Hi! Ed
I took another 91 13b NA apart today, it had good compression on a
gauge six good pops at the exhaust port when rotated by hand, didn't
smoke & ran well . The slots were 2.26 to 2.43 wide, the apex seals
worn concave by about0.15mm on each side. by the wear on the eccentric
shaft bearings this engine had spent a lot of time at high revs. I doubt
very much that your engine demise was called by seal clearances, You are
not missing any tools by any chance?
Georges Boucher
-------Original
Message-------
Date: 04/17/05
12:35:17
Subject: [FlyRotary]
Re: New rotors, New housings
I do know that my worn slots measured 1.98 mm at the bottom and
range from 2.16 to 2.26mm at the top - giving an out of vertical of from
0.18 to 0.28 mm. The specs say a maximum feeler gauge between an
inserted apex seal and wall is given as 0.15mm, I could insert an 0.18
mm feeler in some and an 0.15mm in all. I don't think
I would feel comfortable flying with a rotary in that shape (anymore
{:>)). Putting them in an auto is a different story - if it
breaks - park on side of the road rather than strain the eyeballs
looking for an airpatch.
Ed A
----- Original Message -----
Sent: Sunday, April 17, 2005 3:24
PM
Subject: [FlyRotary] Re: New
rotors, New housings
|
Ken I screwed up on reporting the rotor slot
width, it should be 2.17 to 2.26mm not 2.017 to 2.026mm
Georges
-------Original
Message-------
Date: 04/17/05
07:51:53
Subject:
[FlyRotary] Re: New rotors, New housings
--------------
Original message from keltro@att.net (Kelly Troyer):
--------------
Georges,
Are these numbers in reference to the apex
seal slot taper from
the bottom of slot (2.017 mm) to the top of slot (2.026 mm)
which
is a taper of (.009 mm) or about 3.54 thousands here in
the 48 ??
--
Kelly Troyer
Dyke
Delta/13B/RD1C/EC2
--------------
Original message from "Echo Lake Fishing Resort (Georges Boucher)"
<echolakeresort@telus.net>: --------------
|
Correction, the readings were 2.017 to 2.026mm
Georges
-------Original
Message-------
Date:
04/16/05 19:05:31
Subject:
[FlyRotary] Re: New rotors, New housings
|
Hi! Ken
Do you you cut on a taper, where does your taper
start? or do you just skim 0.015" off each side for a
total of 0.030". I just measured the two rotors that
were in a "GOOD" running 92 13b NA & got a reading
of 0.017 to 0.026mm, I guess they are toast.
Georges Boucher
-------Original
Message-------
|
|
|
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