Exhaust Valve Caps

TobbyT

TobbyT

Member
exhaust-intake.jpg vlave cap.jpg

Why would Ford put a cap on this Valve? It must have some purpose. I've never seen a valve with a cap before. Without the cap, the exhaust valve is about 1/8 inch shorter than the intake valve. It's the same length with the cap on.

I'm having engine trouble on my 1950 F-3. I pulled the intake on my 1950 F-3 and noticed the Intake and Exhaust valves were different. The 1st picture shows the 2 styles. The Exhaust valve has the cap and it’s the one on the left. The 2nd picture shows the Exhaust valve disassembled. Notice the cap on the right of the picture.
 
I believe that the cap is an early version of a roto-cap it allows the valve to rotate slightly on every exhaust cycle to help prevent the valve from burning and mininizing the chance of getting carbon between the seat and valve face. A lot of truck engines with stellite valves in the 70 and 80 used this. I worked in an automotive machine shop 30 years ago so this may not be true today. Regards, Brian
 
Dec 211975 is correct, that is a rotor valve assemably from some industrail engine. I don't where that valve came from but I've never seen one in a flathead. Walt
 
Thanks for the info. I can understand the theory behind the cap now. It makes sense. I assume in practical use the cap didn’t make much of a difference in performance.
 
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