Then I found this on a bearing website. Click on the link and read the second paragraph

http://www.bocabearings.com/Issue5.aspx


If you cannot see it this is what is says:

HP ENGINE BEARINGS - HIGH PERFORMANCE!

It is normal for fuel to slightly leak out of the front bearing from the crankcase of a nitro engine because it is not a perfect seal there and the inside of the crankcase is pressurized. Other than that fuel should not leak out of your engine in any other place. So, not only must you have good seals in the top part of the cylinder - around the head gasket, the glow plug, and, of course, the piston itself - but you must also have good sealing in the lower part of the crankcase. This involves the seal on the backplate, on the front bearing housing and at the front bearing area of the crankshaft.

The solution is Boca Bearings High Performance Engine Bearing series. Designed with our exclusive 2RU rubber seal technology. The High Performance Series were created specifically to eliminate fuel leakage problems and to provide better compression in your engine. If you are experiencing the dreaded spray out of the front of your engine, HP bearings will substantially increase your over-all performance.