Watch video link first!

After adjusting my pushrods trying to fix a front cylinder valve train noise I fired it up to check it idled properly. Can't say I've ever seen this before. I did install new OEM breathers after doing a big bore kit, and did verify that the front breather was installed correctly after seeing this. I couldn't find anything specificly about this on the forum. It seems weird that one would pull air and the other would push. Does this seem correct or is there an issue here?
I did check compression on both cylinders. Both are dead on 150 PSI.

 

Maybe the one on the other cylinder is screwed up?

 

What breathers did you install? Early or late "stamped" type? Rebuild or complete breather assembly? I am with Max, rear not working properly or perhaps rocke box gasket installed wrong; covered up breather passage? Pull it and take a look.

 

Finally had a chance to tear her down and see what was going on. You guys were correct in assuming I installed the rear breather umbrella upside down. Unfortunately the gasket bonded a little to well to the rocker support plate and tore on removal, so now I'm waiting on parts. I have been looking for a mysterious valve train rattle noise so maybe this will fix it? Who knows, only one way to find out.

 

Well that would make for some high crankcase pressure...