zoom Posted September 17, 2009 Report Share Posted September 17, 2009 2 race nights on this motor since built. started losing power. cylinder leakdown showed good except for #5. air coming from valve covers. Pulled it down, all other cylinders show a black fire pattern, cylinder 5 less so. Valves look like cylinder was running lean. Picture of the piston, the head has what looks like melted aluminum "flash" welded on it. If you look close, you can see the top compression ring in 2 places. Anyone know what I did wrong? Link to comment Share on other sites More sharing options...
MrX Posted September 17, 2009 Report Share Posted September 17, 2009 Their two things that could have gone wrong. 1) the air gap of the ring was to tight. check your rings befor installing on to piston by placing them in the cyl. and checking with a feller gauge for proper gap. 2) the ring may not have set right when it was instaled. I hope this helps you. Link to comment Share on other sites More sharing options...
Truck99 Posted September 18, 2009 Report Share Posted September 18, 2009 I agree with incorrect ring gap - ring ends butt together and pop the top of the piston off. Link to comment Share on other sites More sharing options...
sandersracing Posted September 19, 2009 Report Share Posted September 19, 2009 I had one look like that to only one race on it. Link to comment Share on other sites More sharing options...
HiTech Posted September 19, 2009 Report Share Posted September 19, 2009 we had four of those in one race in sa ..finished fifth in a pro sedan race .i was suprised how fast the car ran with all four pistons showing rings .blow by from hell made me take a look ..... it got hot .. Link to comment Share on other sites More sharing options...
zoom Posted September 21, 2009 Author Report Share Posted September 21, 2009 could something have accidentally been dropped down the carb to cause this? Link to comment Share on other sites More sharing options...
MrX Posted September 21, 2009 Report Share Posted September 21, 2009 could something have accidentally been dropped down the carb to cause this? Yes it could have it would have beat the shit out of the piston. from the pic. it dosn't look like it. Link to comment Share on other sites More sharing options...
Truck99 Posted September 22, 2009 Report Share Posted September 22, 2009 could something have accidentally been dropped down the carb to cause this? Mark, it looks like improper ring gap. Are you certain the ring gap was in line with what the manufacturer of that piston recommends? Link to comment Share on other sites More sharing options...
txtom Posted September 22, 2009 Report Share Posted September 22, 2009 Chase is correct here. Improper end gap on the rings. Damage is not consistent with a foreign object getting in there, outside of the pieces of piston that were knocked off. That aluminum flash on your head is the pieces of piston that were popped off. Link to comment Share on other sites More sharing options...
zoom Posted September 22, 2009 Author Report Share Posted September 22, 2009 I checked the ring end gap on all the cylinders, but apparently I missed this one. dadgum it I need to have folks stay away with their beer when I am building a motor. WAIT, what am I saying?. Yall come on over! Looks like we caught it early, cylinder looks really good. Hone it out, New rod and piston, rings, bearings, and back together with it. Link to comment Share on other sites More sharing options...
Double D racing Posted September 22, 2009 Report Share Posted September 22, 2009 we had the same thing a while back.someone quoted a comment about too much or not enough timing.....????? Link to comment Share on other sites More sharing options...
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