I have the 305 V-6 in my '68 GMC. My original Bendix-Stromberg carburetor is long gone due to serious mechanical problems and missing parts.
I have replaced it with the ubiquitous Rochester 2-barrel using a custom machined adapter plate. This Rochester was factory automatic choke, equipped with vacuum and temperature coil spring setup. Because the truck was originally manual choke, I have attempted to modify the Rochester by removing the aforementioned auto choke goodies and splicing in the original choke cable brackets. I'm sure that is where the trouble began.
I can't seem to figure out the idle with the engine cold and on full choke vs. idle with a hot engine and no choke.
With a cold engine started with full choke, I set the idle where it sounded right to me. Then allowed the truck to warm up, opened up the choke butterfly, and drove it a little. Everything seemed to run fine.
Driving down the road, thermostat open and engine good and hot, I step on the clutch to coast to a stop. The engine dies and will not maintain idle where I have it adjusted. It starts and runs fine, but only if I keep my foot on the gas.
I obviously know only enough about carburetors to get myself in trouble. Any help with this would be greatly appreciated.
1. Any ideas what the rpms should be for a full-choke cold start idle?
2. What would cause it to run with the choke open and engine cool, but die once the engine is hot?
3. Vacuum port (originally for the auto choke) was reassigned to run the vacuum advance on my distributor. Could this be a big problem?
Very Confused,
JC
