1950 Buick - starting hard when warm

Hi guys,
Hope someone can help shed some light on this problem. I have a 1950 Buick Special 248 6volt. It starts fine when it's cold. However after I've driven it awhile and it gets hot and I shut it off and go to restart it, it starts really hard. By that I mean the engine turns over and I have to hold the pedal to the floor for about 15-30 seconds of continuous cranking before it finally starts. I've tried not touching the gas at all (I also have a push ****on starter), tried holding the pedal half way down, and putting it to the floor.

As I said it starts fine when cold, but has a hard time starting when it's warm. Any advice from anyone would be greatly appreciated.
Thanks
Scott

 

sometimes it could be the float level in the carb,

 

Modern gas boiling off when warm and causing a over rich mixture most likely. You minght try lowering the float a bit 1/16 max.

 

How do I lower the float?

 

Hi Scott. You said it turns over fine, just won't fire at first. And you hold the throttle to the floor without pumping?
One of two things...too much fuel (flooded) or too little.
When the car finally starts, is there heavy exhaust-smoke?...probably flooded...needle-valve not seating and not shutting off fuel completely. When shutting the engine off after running, the residual fuel-pump pressure continues to dump fuel past the valve, and into the engine. If this is the case, it's because of debris in the fuel, or an old sticky valve.
Is the engine possibly starving for fuel? Does the engine tend to stumble on take-off? Verify if the accelerator-pump is working as it should. If not, it'll need replacing. If it's borderline, just pump the accelerator when starting.
If you have debris in the fuel, you know what you're gonna have to do...make sure tank, pump, and lines are clean, new filter, clean carb-bowl. If the accelerator-pump isn't working good, or you need to replace the needle-valve, just get a rebuild-kit for your carb, and rebuild it. Go on line to find tutorials...you can do it. If you have questions, ask here or PM me.
As far as fuel-float level goes, chances are that if it was running good before, the level is correct. However, specifications are usually included for checking this in the rebuild-kit, and it's a simple matter of bending the small tab that contacts the needle.
Good luck.

 

Vapor lock? Make sure the fuel lines arent touching any high heat source.

 

I considered vapor-lock too, but on any of the straight-eight Buicks I've had, the fuel-line is plenty far enough away from any heat-source. Good to take a look, though.

 

Another thought is the heat riser flap on the exhaust manifold working freely. Stuck in the closed position can cause hot starting/running issues.