[MagmaJct]

Gasoline has undergone changes over the years that old carburetted engines are just unable to adjust for. The major change is the oxygenation of the gasoline. Not only is that gas "leaner" to reduce CO emissions, but it also has a lower vapor point than gas of 30 - 40 years ago.

When the engine is running the carburetor gets a sufficient supply of cool fuel from the tank with minimal heating from the engine and related components. However, when the engine is shut off, and the cooling system is stopped. The heat is allowed to soak into the carburetor and the fuel system around and including the pump. This makes the gas vaporize and even "boil" out of the float bowl and into the intake manifold.

Not only does this flood the engine, but the vapor build up in the air cleaner causing a very rich mixture. In many cases the easiest way to get the engine started is to gradually press down the accelerator while cranking the engine. As it starts let off enough to maintain a stable RPM to purge the engine of the rich mixture.

This is the procedure I've used for years. Ideally, I'd like to find a phenolic spacer for my VW, but it seems I'll eventually have to make my own. I eventually found one for my truck, and it seems to work well. However, I will eventually install the Quadrajet.