My 1971 Corvette has a 350 4BL with 750 Holley Carb. And it will start up Great! Idle Great! and after it's been running awhile in the driveway I take it out on the road. Once I'm out for about 15 minutes I start to get a hesitation in the acceleration and after another 8 minutes or so of driving the engine is sputtering and clunking along till I put it in park and then it slowly stalls out.

Sounds like and acts like Vapor Lock to me? Cause I let it sit for about 25 minutes till the engine cools down and the Vette starts right up and drives nicely straight back to my garage.

Your thoughts and Suggestions?!?!

Thanks Ed

Sounds more like a fuel filter stopping up, either the "sock" in the fuel tank, or the filter for the carb. Vapor lock, if it was actually happening, would likely be more pronounced after the hot engine sits for a few minutes....and everything under the hood started baking. Real vapor lock these days is hard to happen, given the crappy fuels available....just not as volatile as they were back in the days of real fuel. 

I would start by checking the filters first.

Joel Adams
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If this happens on muggy days, it could be carburetor icing.  After sitting for 5 or 10 minutes the heat from the engine will melt the ice and it will run fine.

Next time it does this, pull the air cleaner and look down the carb and see if there is any icing there.