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 #1 and #2 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. #1 cylinder is burning the leanest with very grey plugs, #3 plugs have a good color also but not quite as lean as #1. #2 plug on top is quite black (dry) while the bottom plug looks good. #4 plugs both look very black (dry). #1 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
