Running rough when warm

[lnirenberg]

Finally on the road and the problems begin. Work this winter included new Edelbrock aluminum dual plane performer intake w/ new 600 cfm edelbrock electric choke carb, comp cam 1.6 roller rockers and new hydraulic lifters. Engine is a base 350 that has been bored .03 over and compression raised to 9.7-1 (that work was done by previous owner). Car starts right up runs great when cold and continues to run great holding a steady 6-700 rpm idle with a nice rumble. When I shut it down and then restart it, it turns over a while before it finally catches and the idle is very rough and will stall if I don't rev it a bit. Once it gets driven a few minutes it runs fine again. Any help would be most appreciated.

 

[cfour93]

Finally on the road and the problems begin. Work this winter included new Edelbrock aluminum dual plane performer intake w/ new 600 cfm edelbrock electric choke carb, comp cam 1.6 roller rockers and new hydraulic lifters. Engine is a base 350 that has been bored .03 over and compression raised to 9.7-1 (that work was done by previous owner). Car starts right up runs great when cold and continues to run great holding a steady 6-700 rpm idle with a nice rumble. When I shut it down and then restart it, it turns over a while before it finally catches and the idle is very rough and will stall if I don't rev it a bit. Once it gets driven a few minutes it runs fine again. Any help would be most appreciated.

One idea might be the electric choke element. Depending on how long you run it and then start back up the element may cool down and contract just enough to cause this problem, like i stated depending how long you ran it before. I experienced this on a previous car i owned and believe it or not the choke was adjusted incorrectly. Once the adjustment was figured out problem stoped. The other thing which you can determine is the fuel line does the fuel line get to hot and cause the fuel to foam in the line between starts just enough to create a short peroid of rough idle until liquid fuel flows again.
Just some theroy to apply to your question.

 

[jdp6000]

I'll agree with choke or float or gas line. I suggest next time you start it cold to observe the function of the choke and carborator. When you try it again warm check again. Note if it does anything different. It probably requires a simple adjustment.

Jim

 

[JohnZ]

The choke may be set too rich. When you shut if off, the thermo element inside the choke housing doesn't get power any more, cools off quickly, and it sets the choke for the next start, even if it's a warm day (the choke only remains open when it's getting 12 volts). Adjust the choke housing a notch or two toward "Lean" until you get the choke action you want when it's cold and it doesn't load up with a warm start.

 

[wishuwerehere82]

Do you have a "thick" heat insulator gasket under the carb?

 

[lnirenberg]

The choke may be set too rich. When you shut if off, the thermo element inside the choke housing doesn't get power any more, cools off quickly, and it sets the choke for the next start, even if it's a warm day (the choke only remains open when it's getting 12 volts). Adjust the choke housing a notch or two toward "Lean" until you get the choke action you want when it's cold and it doesn't load up with a warm start.

It appears another job well done. The choke was set up to rich the side of the center mark and I leaned it up a bit and it now start and runs fine @ operating temp. Thanks one and all.