High EGT

Hi Sean

It is indeed possible.  Once I had an engine that we found a tiny piece of rubber from inside the fuel line had come off and got into the tiny chamber just over the needle inlet inside the carb body.   High EGT suggests you are running lean so if you are confident in your fuel think of something that may be allowing air to enter that side.  In my case it was intermittent and with vibration it would block or unblock with running.  It however was also rough running, which you have not stated has occurred.  Carefully check the intake socket for sealing/splitting and if you ever had the intake runners off suspect a split O-ring on the manifold to cylinder head.  

Cheers

RW,

Never had the manifolds off/near new engine - still under 80 hrs.

Never noticed loss of power/rough running/change in engine note/vibration.

Heading to airfield in a few minutes - as a first step, will remove float bowls and check for debris/water/etc 

Several hours later:

No foreign material/water/etc in float chamber

Random thought:

I know, from experince, that running on one ignition can cause high EGT readings.

What if one spark plug has an intermittent fault ie doesn't show up in preflight ignition check but fails to spark at certain rpm/load situations?

Could this cause a high EGT reading??

https://www.youtube.com/watch?v=-NoFfck5v4c

Sean, watch this.  Get out your good multimeter and be sure it is a good probe.  I have never seen a system firing on one plug run hotter.  With dual plugs each plug is actually not in the optimum position.  Both sparks must meet at the middle of the chamber when they fire to get a good and complete burn.  This  is how when we do a MAG check we generally see a drop in performance of a few hundred RPM.  

For the most part only a lean burn will give you a high EGT. 

Cheers

RW

When "we do a MAG check" its preflight, minimal load on the engine - try doing it in cruise and then initiate a climb (load) - you will likely see an EGT rise.

Having said that I think its time to remove the offending carburettor and do a detailed inspection/clean.