Other Help me understand my damage.

[MADMAT]

I believe my Wisecos called for .005 and I was told that anything less would be bad.

 

[chookc]

I run a 1050 setup coffman on my xpl and safely run on 98 fuel with ams oil up to 1275.
so 1050 should be a safe figure but again depends how close the probes are to the ignition point. As far as gaps go I upto to 8 though is acceptable onthosse pistons...

 

[OCD Solutions]

I believe my Wisecos called for .005 and I was told that anything less would be bad.

I had heard the same thing and thought that by going .0055 to .006 I would be more than good.

I reread some posts by Bill O'neil and he made a good point. With the proper breakin and warmup EVERYTIME, you could make .005 work for a long time but forget ONCE, and you are done. 0.007 to 0.008 and you will run for a longer time and have much more forgiveness.

He also goes on to say there is absolutely no good reason for running Wisecos in a rec engine. With my limited experience I would have to agree with him, at least on larger bores without the proper clearances anyway.

I aimed for 1150° knowing that I was peaking at 1250° for brief periods, (a few seconds anyways). My probes were as close to the manifold flange as physically possible and extended out into the center of the exhaust flow.

You can see in this pic the brass fitting where the EGT probe was fitted in the manifold right above the Spigot mount.

 

[chookc]

Yeah looks very close to where mine are located. Sorry to clarify i ran my engine in race spec set to around he 1150 mark within about 20 degrees of each other. that allowed me some forgivness on long straights or real tight turns... but never let the engine go past 1250.

I think you need the bigger clearences...
Are you running the di crankcase cooling on yours.. It does help a lot on this setup...

 

[OCD Solutions]

No, I never got that far. I fought the setup on this ski so much and was finally happy to have it running good. I had 25hrs on the last set of pistons and was finally happy with my jetting, performance and temps when the crank let go. I had done in 3 top ends on that crank so it wasn't much of a surprise. I had resisted changing it earlier until I had all my top end issues sorted.

I figured I was in the clear, dropped in a new crank, new pistons in a new bore and I was off and running again. You can imagine how it felt to open the engine at 4hrs and see this.