![]() |
Some of this discussion has gone off in the weeds with all the discussion of starting procedure and some incorrect assumptions. Check the original post. The purge valve is at ICO when the boost pump is run for 30-45 secs. That does nothing but circulate fuel through the distribution spider - nothing goes to the cylinders until the purge valve is pushed in. Similarly, the original post does NOT indicate starting at 1/2 throttle.
|
Quote:
|
Ring Gear
The ring gear has (or had) 149 teeth and the starter is a 149 NL so there is no issue there.
But to explore a different direction, I am using a momentary contact push button switch rated at 16 amps for my starter. It is ACS part number 15-131, just like 15-132 but momentary contact style. Is it possible that the switch bounced or stuttered causing the starter to try to re-engage while the ring gear was turning? Anyone hear of a starter switch problem that caused ring gear damage? |
Timing
As several have suggested, I have concluded my problem is at least partially related to my lightweight prop. I found the following quote on the Emagair website under "Tips and Tricks".
Low Mass Props: Kick-Back PrecautionI will certainly try that when I reset the timing. |
That's a better explanation than mine!
Good write up John. That's what I did, but I used the more aggressive curve so I didn't lose anything on the top end. In fact I still gained a little since I split the extra 4(?) degrees that the "B" curve provides.
Lance |
Kudos to Aero Sport Power
I just wanted to report on the excellent support I have received from Aero Sport Power regarding this incident. I called them Monday morning to ask for advice and Doug immediately arranged to have a new flywheel painted to match my engine and shipped to me. The new part, smelling like fresh paint, was on my front doorstep on Wednesday night when I got home from work. That is all the way from Canada to SoCal. I just have to send my damaged flywheel back to them and my cost is basically the price of just the ring gear alone plus shipping. It would have cost me more to have a local engine shop remove and replace the ring gear on my flywheel. Thanks to Doug and Margaret and Aero Sport Power for helping me get this repaired.
Now I just have to install the new flywheel and reset/double check the timing. My plan is to re-time with a bias of 2-3 degrees after TDC and try again. |
That's fantastic customer support. Kudos to Aero Sport, and good luck on your next start!
|
Update and More Questions
This is an update to my original post. I need some help understanding these P-Mags.
I installed the new flywheel this morning and got the prop re-installed. As a check, I performed another ?pull thru? test described by the Emagair installation manual to see if the timing was still set at TDC. As a reminder, in this test the spark plugs are out but grounded to the engine and the prop is rotated by hand while observing the spark timing relative to the timing marks. However, this time a watched very carefully as the TDC mark slowly approached the hole in the starter. To my surprise the #1 spark plug fired about 1.5 teeth (about 3.5 degrees) ahead of TDC. I repeated this several times with the same results except the two P-Mags would sometimes fire at different times by as much as half a tooth (1.2 degrees) in spite of being set exactly the same. At this point I was thinking the P-Mags were just set advanced by 1.5 teeth and this was the probable cause of my kickback. I decided to reset the timing to 1 tooth after TDC which is about 2.4 degrees retarded. So I rotated the prop to 1 tooth after the TDC timing mark and followed the P-Mag instructions to re-time them. After doing so, I performed the pull-thru test again and found that the #1 spark plug fired ? tooth before TDC. What? There is that same 1.5 tooth offset advanced from the set point again. So then I rotated the prop to 2.5 teeth after the TDC timing mark and retimed the P-Mags. This time I found that the #1 spark plug fired 1 tooth after TDC. Again, there is that 1.5 tooth offset. I haven?t found anything in the P-Mag documentation about an offset between the set point and the spark during the ?pull thru? test. Maybe this is an intentional timing offset to account for latency in the P-Mag electronics, or maybe there is a problem with my P-Mags. I don?t know. I plan to call Emagair on Monday but I thought maybe some of you P-Mag owners may have encountered this before and can provide an explanation. I was just not ready to try another restart today and risk another ring gear until I can explain this behavior. Anybody out there seen this before? |
Still looking for P-Mag help
Anybody out there with P-Mag experience that can give me inputs on the post above?
|
Quote:
I'm guessing you're doing it the correct way but just wanted to throw it out there. |
| All times are GMT -6. The time now is 09:19 AM. |