[DeTomaso] Exhaust Valve Not Closing?

[Dan Courtney]

Art,

I've had this problem in several forms, including one time when I missed a shift on the backroads to Montery one year.
The #5 lifters in a 351c don't get much oil.
I'd recommend first listening with a steel rod along the valve cover, until you find which cylinder it's coming from, the pop the valve cover and check for loose rockers and bent pushrods.
You can also check the adjustment of the valves (instructions attached)
If you think the valve is not closing a leak-down test should answer.
It's not too big a deal to pop the valve cover and change a lifter, but don't drive it hard if you think you may have a broken spring, been there done that before and a valve inside a piston is not an easy sight.
You may also have made valve/piston contact when they floated and bent something.
Hopefully you just bent a pushrod or have a collapsed lifter.

Dan
Dan F. Courtney

La Jolla, CA

(858) 551-5455 Phone
(858) 551-5456 Fax