I'm curious about how you have 0.4 ips vibration problem?
Are you sure its the crankshaft?


Sorry, I disagree that automotive people can do a better job.
How many auto shops check the nitriding and heat treatment?


Pistons and rings are not part of crankshaft balance.
Pins bearings?


Kent Felkins
Tulsa

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Let me set some things straight for ya. Any good racing machine shop
can balance a motor far better then the vast majority of FAA approved
places. In fact Lycoming can't even built a crank for some models they
produce that won't break, and they have killed people this way. So much
for the FAA keeping a close eye on quality... As for nitriting and heat
treating, this is an every day detail in the racing market and is down
to a science, not black magic... Pistons and rings and circlips are
part of the rotating/reciprocating assembly and need to be balanced
too. Good shops even add in a factor for the weight of oil that clings
to the balanced mass to get it perfect.