Last December the truck started blowing white smoke while idling, but pretty much went away while driving it. I thought initially it was flooding, running rough, and the bolts that hold the top air horn on the carb were loose. So I tightened them up (at least a full turn each) and it ran better. After that I decided to do a Weber 32/36 and Offenhauser intake swap. I just finished up the swap this past weekend and went to change the oil before I started it and at least a 1/2 quart of coolant came out first. I filled it with oil and started it, and the temperature rose really quickly, about 3-5 minutes after starting it, it was way past the normal operating temp. Thinking the problem is a head gasket I just ran a compression check and got the following readings: #1: 168 psi #2: 138 psi #3: 143 psi #4: 169 psi The threads on the #2 and #3 spark plugs were wet. Although these readings indicate something is wrong with #2 and #3 I would have expected much lower readings for a blown head gasket. But, I guess if one of the water jackets between #2 and #3 blew out on both sides that would explain this. The timing chain and guides were replaced about 20K miles ago, so I don't think that is the coolant leak. I just wanted some confirmation that the head gasket is the problem before I go take it apart. Thanks for any help.

 

If you have a lower comp in the center 2 cylinders and water on the plugs, then you have a leaking head gasket or a head problem. I would take the head to the shop and have it checked and put in a new head gasket.