ORIGINAL: Stickbuilder
Here's a little helpful hint....If you have room in the cowl under the engine, find a tiny tank, or use a small asprin bottle, and fit it with a tank plug. use 2 lines, fit one with a clunk and inside line. Run the vent tube from the engine crankcase vent to the vent tube in the small tank, and run a piece of fuel tubing from the clunk line to where you can access it. When you are through flying for the day, pump the spent oil from the catch tank, and dispose of the gunky stuff properly. You would be surprised how much cleaner your plane stays, and how much easier the clean up is. Oh yeah, clamp the catch tank to the firewall, so it does not flop around inside the cowl.
Bill, AMA 4720
WACO Brotherhood #1
Bill, that may work on some engines, but other four strokes don't like the restriction even a little. One of our guys was using that setup on a Mag 52 four stroke. We just couldn't get the engine up to speed or down to idle. I finally had him just vent the crank and with out this minimual restriction, the engine run fine. I've seen serveral other post about restricting this vent and none claimed success.
If you don't want the junk dripping out of the bottom of the cowl, drill and tap a nippple in the intake like a lot of the 4 strokes are using now and vent it there. In addition, use a velocity stack to hold in the blow back through the carb. I put one off the new O.S 56 on my O.S. 52, Same carb, and what a differenct under the cowl. I'm making some for my 70 and 91s now. Don't know if it runs better, but it sure runs cleaner.
Don