Sucked a Valve in 350 Chevy OMC

Merdoc

Cadet
Joined
Jun 25, 2004
Messages
15
I have a V-8 chevy Omc Cobra and #8 cylinders sucked a valve in last year, it was taken apart and the heads were done and reinstalled. Just ran it again the other day to the slip for 25 minutes and was ok, After sitting for hours we took it back out and after runnong it up for 10 minutes the rpms dropped we babied it back in and took it apart and the same cyl sucked a valve? Manifold? Riser?
 

Boomyal

Supreme Mariner
Joined
Aug 16, 2003
Messages
12,072
Re: Sucked a Valve in 350 Chevy OMC

What does 'suck' a valve mean?
 

Merdoc

Cadet
Joined
Jun 25, 2004
Messages
15
Re: Sucked a Valve in 350 Chevy OMC

The valve gets sucked farther in to the head, instead of the top being flat it now dishes down in the middle and the stem is about 1/4" higher from doing so....
 

Reel Poor

Vice Admiral
Joined
Jan 29, 2005
Messages
5,522
Re: Sucked a Valve in 350 Chevy OMC

For some reason the cylinder combustion chamber temps are above normal.

Running lean
Ignition timming - total advance
Cam lobe problem
improper valve adjustment
improper valve spring tension
Wrong spark plugs
vacuum leak
 
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