Mystery Solved!!!!!
 

7 years I tell you, 7 years. My turbo 337... wonderful plane, but you get it above 12000 and 23" and the sucker would vapor lock. Yep, tried everything... you name it. I tried it. Got it so I could go to 25", but then.... vapor lock... dang!

So... we tried one more time. I was sceptical of all the media hoopla, but we put it on. Here are the results:

Cost: $15
Material: 08-00602 THERMO-SHIELD 1 1/2 X 15FT RLL
Time: 30 min
Supplier: Aircraft Spruce
Location of use: Fuel line from gascolator to fuel pump.

Results: Went to 16000', 32", 2hrs. Guess what..... no vapor lock. It's a miracle!

same here, four years ago insulated every gas line that was exposed f/r never had a vapor lock after that