Carb Heat Soak

@Dana67Dart I've had minor issues with gas percolating in my carbs here in northern CO, not enough of a big deal to warrant paying extra for ethanol-free gas but it's still there. I run a phenolic-body Street Demon on the 360 in my Duster with a 1/2" wood-fiber spacer and it still gives slight symptoms of fuel evaporating and the vapors collecting in the carb venturis/intake plenum (have to hold the throttle open a tad and crank for a few seconds before it'll fire on warm starts). I still usually pop my hood partially open once I park and my engine is fully warmed up to let the heat flow out of the engine bay instead of just collecting around the carb. Same goes for the Edelbrock 1406 on the 360 in my truck. The Duster's engine has Edelbrock heads so no exhaust crossover to speak of but I rarely miss it unless I try to drive the car in 20-degree or lower weather which is rare. The D200 has a regular Performer intake on factory iron heads but I blocked off the exhaust crossover on that. I've thought about installing a factory dual-snorkel air cleaner with a functional heat riser and warm-air intake tube on the truck as it can be a bit finicky the first few minutes in cold weather but I'm about to move to Georgia where it rarely gets below 60 degrees in the coldest months.

Exhaust crossover IMO just shouldn't be used with aluminum intake manifolds in about 90% of cases. They just get way too hot too quickly (speaking from experience). Warm air induction with some type of valve to switch to "cold" (non-heated) air when fully warmed up is much more effective. Since aluminum transfers heat much faster than cast iron an aluminum intake manifold gets warmed up to the same temp as the rest of the engine after 5-10 minutes of run time especially if it's a non-Air Gap type which I generally don't run anymore on street-going vehicles if I can.

I think after I move I will be upgrading the fuel system on the Duster to have a fuel return line with pressure regulator and an electric pump as I have a feeling once I jet up to compensate for the lower altitude the increased fuel demand will be too much for the current setup which is basically factory 5/16" line with stock-type mechanical fuel pump dead-headed to the carb with no regulator.