In my eariler post I had numbered my cylinders wrong. Below is the e-mail in it's entirity with the correct cylinder numbers. Sorry about that.
>I'd like to hear from anyone with experience on 0-200 >engines. Mine is basiclly stock as removed from a >C-150 with the same carb, heat box, baffling, air filter, etc. >The engine has new mags, wire harness, cleaned and >regapped plugs with new plugs in the top holes of >#3 and #4 cylinders. > >Yesterday I pulled my prop to send back for re-pitching. >Before doing so we did a compression check. Three >cylinders were 80 / mid 70's and one was a bit weak >at 80 / 64. It seemed to have an exhaust valve leak >that is probably carbon on the valve as air is exiting >the exhaust pipe. This is on a high time 1800 hour >engine. > >My question concerns the fuel/air distribution. #4 >cylinder is burning the leanest with very grey plugs, >#2 plugs have a good color also but not quite as >lean as #4. #3 plug on top is quite black (dry) while >the bottom plug looks good. #1 plugs both look >very black (dry). #4 cylinder, the one with the exhaust >leak and low compression, is the one running with >the leanest mixture. > > Is this poor mixture distribution >common or should I suspect air leaks. The carb >was basiclly rebuilt by an A&P friend of mine when >installing the single piece venturi and he does VERY >GOOD WORK. The carb butterfly shaft is worn and >needs new bushings but the side with the most play >has the rich running cylinders. I seem to recall a note >about mixture distribution with the single piece venturi >but that work was done 6 or 8 years back and I have >trouble remembering what I had for breakfast this >morning. :-) > >The engine starts well and basiclly runs smooth except >some vibation in the 2100 to 2300 rpm range in flight. >I attributed the vibration to the prop but now I'm wondering >if I have some plug misfiring. > >Give it your best shot. I'd appreciate any input you might >have. I'd like to go after this problem (?) while I'm down >for prop re-pitching. > >Thanks. > >Larry Flesner >
