Vapor lock? What does a T act like if there is vapor lock? What is the cure?
It would behave as if it was running out of gas. It is usually caused by the fuel line being too close to the exhaust pipe. The pipe should cross the exhaust either over or under the exhaust with a couple of inches clearance and then run along the frame rail. Also there should be no place in the line which is higher. That is the pipe should go down from the gas tank to the lowest point and then up to the carburetor. That way any vapor will rise either to the tank or the carburetor. If there is a high point in the middle, the vapor will rise to the high point and compress, but the fuel flow will stop.
Thank you Norm! My gas line needs to be rerouted. I can easily see now where my trouble is. Now I'm somewhat gullible. A friend of mine said back in the day they put snap clothes pins on the gas line to help with vapor lock. I thought I would throw that out if anyone wished to opine.
Aluminum clothes pins
A properly routed fuel line should have no problems with vapor lock. Clothes pins are at best a bandaid on the problem and could even pick up more heat an worsen the problem.
Search the forum, there are many posts on gas line routing. I would strongly suggest your gas line go under the exhaust, not over. That lowest point Norm mentions should be under the exhaust pipe.
Earlier thread on fuel line routing:
I had a lot of trouble with my Centerdoor vapor locking. I put FIBER WIRE LOOM on the entire distance and have never had one problem since. I also put fiber wire loom on all my other 'Ts and again have never had any problems.
I had this problem several years ago and fixed it by rerouting the gas line. However, getting to the realization that vapor lock was the problem was not quick. I analyzed the problem to lack of fuel but more of a time of day thing. I had no problem during the morning drive on tour but seemed to have a problem in the afternoon. Answer, during the morning I had filled the tank before starting the day and by the afternoon I was usually down to half a tank. Less fuel pressure from a half tank. Then the thought of vapor lock set in. The morning drive with more fuel pressure pushed the gas through the line but the lower pressure in the afternoon caused the heat to vapor lock the gas line.