Hi Guys,
I flew my plane today!
All was well except that I'm getting high EGTs. I'm running a 68" GSC wood
prop with 16 degrees of pitch and a Hirth 2706.
Both plugs are brown and not wet. The needle is a 15K2 and the main jets are
160s. I'm getting 1300 degrees on the EGTs at 6100 RPM and it settles to
about 1200 at cruise (4200 RPM) and 400 on the CHTs either way (I did see
the back cylinder go to 500 once). We've tried 170 main jets hoping to run
it richer to get the EGTs down but it made no difference on a second
circuit. Judging by the plugs we are running just fine. The engine seems to
running very well with no indication of wanting to quit (I know go ahead and
laugh, I know Murphy's Law very well thank you!)
I'm using the Mikuni pump and I also have an electric pump but have not
found that it makes a difference. We are wondering at this point if the
location of the EGT probes is causing a high reading. I welded the bosses
about 80 MM from the head gasket (verified with pictures taken of other
Hirths at Sun N Fun). My assistant tells me that the further away from the
engine the probes are the higher the reading because the fuel is still
burning on exhaust. I've looked at a 503 and 582 and the probes are much
closer (more like 30 mm) to the head.
We are thinking about hooking up an EIS with their probes to see if they are
reading properly. I'm using Westach gauges and probes.
Anyone have any suggestions otherwise?
--
Trevor Page
X-Air Ontario Dealer
tpage@...
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