Hello All,
Can any one tell me the best way to test for a burnt valve?
Thanks.

 

Remove the push rods from the suspect cylinder and blow air into the spark plug hole. Listen for air escaping. If it's leaking through the intake it's an intake valve. If it's leaking through the exhaust it's an exhaust valve. If it leaks into the crankcase it's the piston or rings.

 

Thanks so much Bdox, I have a 77 F100 with a 300ci and it has only 57,000 on her, I bought it two years ago with only 40,000 on her. I'm the second owner and it was never beat on but it did sit in the original owners yard for 12 years. If a valve did get cooked what would be the cause for one to burn at 57,000 and would a compresion test tell me if one was bad?
Thanks for your help,
Ken.

 

Sitting for twleve years, it likely got some rusted up valve stems and or valve seating surfaces. Once they start to leak they ususally just get worse.