I understand(and have done) bearing installs so... That part is covered. My question is this. Which clearance should I use? c1-c2-c3(I believe that is how they measure clearance)
? It is a sport engine.

Unless you are making a new engine housing or crankshaft, you are pretty much stuck with the fit the manufacturer has given you! That is unless you plan on buying a handful of bearings from a handful of different manufacturer's, measuring each one to find a specific fit?

Happy Fly'n...

the clearance is between the balls and races not between the engine parts and bearing....CN or C3... CN is standard, C3 is a little looser and better for high speed


dave

Thanks Dave!

Hi!
MVVS and (I think so at least) Nelson supply their .40 engines (MVVS only as a spare part) with Swiss WIB bearings with C4 play.
These ballbearings have plastic retainers. They fits every .40-49 engine on the market except Rossi (who uses a 17mm diameter crankshaft).
I have some if you are interested.

Regards!
Jan K
http://hem.passagen.se/airracing

Jan

The bearings you are talking about are standard issue in the MVVS #3068 Q-500 engine.
The bearings have the C4 internal clearance and the ball cages are not plastic, but TBH - glass fabric filled phenol resin.

The are for extended high speed and high temperature use.

You can see specifications for these bearing types in the [link=http://www.wib-nsk.com/en/products/standards/index.htm]WIB web site[/link]. Look into 'Cages', 'Internal Clearances' and so on.

The Q-500 bearings do fit all other MVVS .40-.49 engines and some other makes too, but the standard WIB bearings, that come in all 'normal' MVVS engines, also last very long and I have never had to replace, any bearing in any MVVS engine so far.