i just bought a 3b with a f-head and it runs good but every few minutes it starts spewing oil out the exhaust and smokes real bad but then it mysteriously stops. i did a compression test to see if the rings were bad but all cylinders were great. Any advise on what this might be or what to try next. thanks

could it be your pcv not working correctly and its sucking to much oil out of the crank case?

Some f-heads don't have a true PCV valve. If you don't have the PCV valve from the factory the other style of ventilation is a metal tube on the driver's side of the motor that just hangs down with the open end towards the ground. The factory PCV valves usually aren't that great to begin with. It could be your exhaust valves. They are constantly needing adjustment and since they are in the block they are a pain to get at, it's easier if you take the driver's fender off. Have you tried these websites: http://www.film.queensu.ca/ConferWeb/CJ3B/Index.html , http://www.g503.com/forums/index.php . They are full of good information and they are very helpful there. They definitely know their shit. Good luck with it and keep us updated.

not the pcv because it just has a vent that goes to oil filler tube

Do you still have the oil bath air cleaner? if you do it may be too full.
This thread belongs in the non hard core section, you might want to move it befor you get more shit about it being in the hard core section.

no oil bath cleaner