Classic/Antique Car Repair: 1951 GMC Chevy Pickup Truck, chevy pickup truck, aluminum pistons

Question
Hi, Could you tell me the valve lash adjustment for a 1951, straight inline, overhead valve, 6 cly, 231gmc pickup?  Thanks.

Answer
Chevrolet valves have always be .006" for the intake when the engine was hot and .013" for the exhausts. However when the 231 cubic inch engine came along they put hydraulic lifters in it and used it on the Powerglide equipped cars. In the pick up trucks with the 236 I would assume that the same features as the Chevy car engine prevailed, the aluminum pistons, full pressure lubrication and the hydraulic lifters. They are adjusted by bring the cylinder to top dead center on the firing stroke, meaning that the rotor is pointed to the terminal in the distributor cap that runs to the cylinder being worked on, loosening the adjusting screw on the rocker until there is a little free play, tightening the screw until all the free play is just gone, and then turning the screw down an additional one and one quarter turn. Good Luck.
Brad