Fuel lines-vapor lock

I'm having the same problem. I was wondering why all these slant 6's likely ran well in the olden days of leaded gas, my dad's 62 Valiant station wagon had no problems ever with it even on the hottest days, and it was routed very close to the engine. But it's the unleaded gas of 2009.

The exhaust manifold is so close to the float(right under it as opposed to any Mopar V-8 setup). When my 70 slant 6 Duster was bought in December it had the fuel line mod as described in earlier posts. It worked great in the cold of Ontario for just starting the engine up in my garage, started instantly. But once I got it on the road in late April it would idle and run well for about 10 minutes until the engine got hot. Then it would almost stall at idle and when in gear but not on the pedal,like making a turn or stopped.

It helped a bit to move the fuel line away from the engine. Then to cover it with the pipe insulation helped a little bit more. But now that we're into the real summer heat it starts to run bad very soon after startup. And starting it up is also harder now hot or cold.

I think my main cause must be that final bit of fuel line and carb in a very hot spot. I'm thinking like others that a heat shield and spacer may be the best method. Could the octane level of the regular unleaded gas be a difference too between our Canadian gas being 87 and it being maybe a bit higher and better in the US???

The Big E