Valve geometry, valve rotation??
Thread Starter
Racer
Joined: Sep 2005
Posts: 330
Likes: 0
From: Lurkerville
Valve geometry, valve rotation??
Car has been running real ruff lately, like it is down a cylinder. Tried playing with carb and timing with no possative results. Can not get manifold vacuum above 6 so I did a bubba leak down test. 40 psi to each cylinder found an intake valve that wouldnt seat, hear air blowing out carb. Removed rocker and the marking on top of the valve seamed odd to me. First one is the intake that would not seat, second one is on a different cylinder, its the only two marked like this. Is this normal? Sorry but little blurry.
Pro
Joined: Jan 2009
Posts: 576
Likes: 3
Wouldn't be able to give you any usefull answer if I tried but it reminded me of the following video:
http://www.youtube.com/watch?v=_REQ1PUM0rY
Around 3:25 you see the valve rotating.
Possible that you over revved it some time ago hence the two marks?
http://www.youtube.com/watch?v=_REQ1PUM0rY
Around 3:25 you see the valve rotating.
Possible that you over revved it some time ago hence the two marks?
Last edited by Imo Apita; Jul 7, 2010 at 04:22 PM.
Burning Brakes
Joined: May 2008
Posts: 860
Likes: 0
From: Stratford Ontario
Those marks are where the rocker is pushing or scrubbing the top of valve as long as it is not grooved at all it is OK. the reason it does this is You do not have rotaters so the valve seldom turns, but thats OK. I would go back to the valve that won't seat and put air pressure back in and tap square on top of valve to slightly and quickly open and close valve. Do not hit top of piston with valve. It may be enough to get carbon buildup off edge of valve, if not it may be time for a valve job. Good luck.
