flyrotary@lancaironline.net Mailing List Archive

Not pessimistic, that is exactly what I want...what may I not be thinking of.

Yes, I replaced some of the corner seals and one side seal that broke when I removed it. I cleaned the side seal groves and endured the side seals moved freely. I almost installed the side seal springs improperly but, IIRC , just before I sealed it up I reviewed a Pineapple racing video that states specifically the positioning of the springs. I also replaced all the rubber inserts.

Yes, I do believe the centrifugal force does drive the apex seals against the housings. If I understand what I read somewhere on this list it helps as the engine is running. However, you are not getting enough force when cranking and if I am not getting the seals against the rear housings to give good compression that may be causing the hard starts.

That being said, the apex seal springs seem to be doing their job in that the seals are springy when I tap at them through the lower/leading spark plug holes. I am curios if perhaps they are not in the exact proper position and may not be sealing enough....yeah, grasping at straws.

Please, keep the ideas coming please. I am more concerned about getting it right, even with the added effort of tearing into it again. I do not wish to spend countless hours trying to tune the EC2 if the real problem is in the engine and as I have stated, it is getting easier each time <groan>. Again, the problem seems to be isolated to the rear rotor based on compression.

Last time I removed the rear rotor without removing the engine from the plane. This time, should that be my mission, I will likely remove the engine, even though I will attempt to not disturb the front housing or the front cover etc. I just think it will be easier to have the stack vertical and the bit of extra effort to actually remove the engine will only involve a few more steps.

Chris

From: Rotary motors in aircraft [flyrotary@lancaironline.net] on behalf of bktrub@aol.com [bktrub@aol.com]
Sent: Sunday, February 13, 2011 11:27 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Low Compression in rotor 2...still

This is a puzzler. How are you lubing the apex springs? Not that that has anything to do with it, just wondering. Also wonder how funtional the apex springs are when the motor is spinning- shouldn't centrifugal force drive the seals out against the rotor housing walls?

I hate to be a pessimist, but did you check the side seals and corner seals also?

Brian Trubee

-----Original Message-----
From: Chris Barber <cbarber@texasattorney.net>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Sun, Feb 13, 2011 7:29 pm
Subject: [FlyRotary] Low Compression in rotor 2...still

To remind y'all, following very hard starting, I discovered bad apex seal springs in my rotor 2 most likely due to detonation. I cracked the keg and replaced the rear apex springs and sealed it all back up. While apart, I did not discover any damage other than the bad springs.

I have been trying to tune the engine, however, even using BOTH my EC2's , I am still having problems with very hard starting. When I do get it to start it is at full lean and I believe only if I switch over to B. Once started I can take the mixture from full lean to a more moderate setting (even if the tuning is still lacking) and it will run on A or B about the same. I have reset A to factory settings. I do have a bit larger injectors, per Mistrals recommendation, but did crank her up to 22. MAP and adjust Mode 3 once started to just over the mid point per the EC2 manual.

It takes an extended period of time of cranking (maybe 50 or 60 seconds...betting my starter is hating me) before it starts and then kinda just starts running as a continuation of the starter being turned, instead of the engine actually "firing up".

I pulled the plugs to check inside and unlike before all the apex seals are nice and springy, HOWEVER, when I do a compression check I am only getting about 60 psi on the rear rotor. I am getting about 80 psi on the front rotor, which is what I expected.

Guys and Gals, I just rebuilt this rear rotor. I am confidant that I got it together properly...but, obviously, I shouldn't be so confidant as the facts is the facts. The rear rotor is only 60 psi which IF I understand correctly would lead to hard starting (and perhaps some rough running as the engine does not seem as smooth when running as it has in the past).

I have been getting it to run with much effort over the last few weeks but kept it at lower power. Today, however I did run it up for several seconds and was able to produce a steady 6300 RPM at 33.4 MAP.

I had it suggested that the new springs needed some time to "set", but I am not really thinking this holds water...or compression for that matter. I also tried squirting in some MM oil and compression did come up a bit, but the REALLY hard start remains.

I am once again mostly resigned to tearing open the engine to see what I must have missed. But since I am pretty sure I did it right before WHAT, pray tell, may you fine gentlepersons suggest I look for when/if I open her up again???? Or, even better, suggestions that would prevent a teardown. FYI, the plugs looked like I would have expected....brownish ashy with no oil build up. Also, I am not having any current indication of coolant in the chambers (don't ask me how I know how to look for that tell tale sign [-(

Please feel free to ask probing questions regarding my method and or attempts.

I am betting ya'll are getting tired of hearing from me.....

Chris Barber

Houston