Ok guys, here goes another newbie question!

Have a 1973 with a 340 in it, has edelbrock performer intake with a 600 edelbrock carb on it.

Starts up cold like a dream, and electric choke works great! When hott and after sitting for at least 30 seconds, starter is cranking fast and hard, and choke is working properly. I have to put the pedal down to about half throttle and cranks over about 6 times when warm then starts.

I put a one inch carb spacer on thinking I may be boiling the fuel, but no help. Fuel filter is clean and flowing gas well. Tried different ignition coil thinking it was heating up and same results. Many cranks then start.

So I now have NO idea of other things to do lol ANY IDEAS will be greatly appreciated!

Thanks again~ Sean

 

duster3 -

It really can only be vapor lock (which you may have checked for) or timing. Th3 73 should have an electronic ignition, so that might rule out a points problem. Most ecu problems happen cold and not hot.

Archer

 

Retune carb idle screws HOT with vacuum gauge. Take 2 degrees out to establish base line and eliminate the issue. Make sure fuel lines ( rubber ones) have been replaced within last couple years and they are wrapped or routed away from heat. What plug are you running number wise and how big is the gap? Is gap closing on you? You can try one heat range colder.

Also, choke should NOT be closing when warm after a 30 second shut down nor should it need a pump of the gas on a hot restart if set up right. It may need a crack of the throttle blades but not pumping the gas.

 

@pk1, Thanks

Thats a good idea about the plugs, I cant belive it didnt cross my mind. I also plan on retuning the carb on dyno with o2 sensor in spring to see how lean it is. I will let you guys know asap. Out here in lower Michigan you never know when you can drive, could be months..or days lol

@Archer, yeah I went through the whole points thing on my 64' Rambler..Nightmare trying to learn it on my own lol But now Im an expert!! kinda

 

Also check when hot.. pull air filter off run the engine when hot turn it off and see if you get smoke out of carb.. If so your floats are not set correct or its not cutting the fuel off and draning the fuel. This will cause hard cranking when hot. Seen this a bunch on e-brock carbs

 

Unless there is actually something mechanical wrong, IE fuel leak, etc, this type of problem is almost universally caused by

modern alchoholized fuel

fuel boiling in the carb bowl and fuel lines on hot shutdown.

Us an insulated carb spacer

Convert to a rear mount electric pump

Setup a vapor return system, IE Wix 33040/41 fuel filter with return line.

Go over fuel system from "stem to stern" and make sure lines are away from header heat, etc. Move lines, construct shields, use insulated sleaves.