Hi Kevin, We had the prop off during the March 2010 annual and it was re-mounted in the same spot on the hub. Engine vibration following the annual was no different than prior to the annual. The increase vibration was noted following replacement of the rubber motor mounts.
After re-indexing the magnetos during the annual (to obtain proper impulse coupling for hand propping the engine), the prop stops at the 11 and 5 position as viewed from the cockpit. Again, the engine vibration post-annual was not different that pre-annual. Thanks, David N95CV --- In [email protected], "Kevin" <kgass...@...> wrote: > > And make sure the prop is mounted in the proper spot on the hub. When your > engine stops does it usually stop with the blades at about 10 and 4 looking > at the front of the aircraft from outside? > > Kevin1 > > > > --- In [email protected], "BobD KSVE" <bevbobdtn@> wrote: > > > > David, > > When I bought my coupe N3047H, it had a bad vibration. After doing what > > you are doing, motor mounts, clearances, engine stuff, dynamic balancing, > > we removed the prop and took it to a prop shop. They promptly red tagged > > it!! (someone had drilled a couple of extra holes in the back of the hub) > > > > A new prop and dynamic balance and empty wallet later and I could finally > > make out the writing on the gauge faces while flying. > > Bob D. > > 1946 415E N3047 "Honey" > > Susanville, CA > > > > > > --- In [email protected], "drdlhammond" <drdlhammond@> wrote: > > > > > > Hi John, > > > > > > How can I/we tell if the rubber motor mounts are bad??? The AP thought > > > they looked normal (i.e. compared to others he had replaced). His torque > > > wrench was "validated" about 1-2 months prior to my job (he questioned > > > both the 60 inch pounds - too tight - and his wrench but a second, older > > > wrench was almost identical). Should we further tighten the mounting > > > bolts? > > > > > > Both magnetos checked good during the March annual and both have been > > > acting "normally" since (i.e. no difference has been noted during engine > > > run up prior to take off). Yes, the right exhaust pipe vibrates enough > > > to touch the cowling at its exit hole (has since I bought the plane a > > > little over 2 years ago). Otherwise, we have not found anything that > > > touches the cowling. I will pass along the suggestion to check for valve > > > spring and lifter malfunctions. > > > > > > The engine vibration reminds me of the old K&B 0.35 nitro/methane/castor > > > oil model airplane engines we used in the late '60s and early '70s. > > > These engines were mass produced and inexpensive. Regardless of how well > > > the prop was balanced, they vibrated! At the time, older modelers told > > > me these engines were not internally "balanced" and thus their vibration. > > > How much engine vibration is "normal" for a 43 year old 4 cylinder 4 > > > stroke engine??? > > > > > > Thanks for your input! > > > > > > David > > > N95CV > > > > > > --- In [email protected], John Cooper <john@> wrote: > > > > > > > > On 8/14/2010 10:32 AM, drdlhammond wrote: > > > > > We could NOT tighten the mounting bolts to the prescribed 60 inch > > > > > pounds (we had metal to metal contact between the engine and the > > > > > mount). At 45 inch pounds there was very little clearance so we > > > > > settled on 40 inch pounds. > > > > > > > > OK, there's something wrong there. Bad rubbers, bad torque wrench??? > > > > > > > > Once that's corrected, there are many possible causes of vibration. > > > > How's your mag check? Any baffles, exhaust or intake parts touching > > > > the > > > > cowl? Broken valve springs? Bad lifters?.... > > > > > > > > -- > > > > John Cooper > > > > Skyport East > > > > www.skyportservices.net > > > > > > > > > >
