Breathers blown off valve cover

[vrbka7v]

I pulled off the track after my heat race and noticed the breathers had fallen off. I put them back on for the A feature and made sure they were tight and they both came off again. Anyone know what would cause this? They are the short steel valve covers from Speedway.

[fast_crew]

Are the breather's fitting properly? Im guessing they are to big for the stacks on the v/c. Even excess blowby shouldn't push them off, unless they are completely clogged up or oil soaked rags restricting the blowby.

[powerslide]

Did you push them all the way down until the tops hit the stack and once pressure built up it blew them off?