I've experienced some cold-weather stalling (600cfm/VS). I noted this moring that it took some 6 minutes for the choke to fully open. As long as the fast idle is on, all's fine, but if I kick it down as I did this morning, some feathering is required. Staying on too long or not long enough? WTF?

JamesC

 

You're probabily experienceing some carb iceing.

Worst around 40F air temp. When gasoline vapourizes as it passes into the airstream it causes the surounding air to drop in temp. The water inthe air freezes and ices up the throttle blades. When the car is idleing there is only a small throttle opening that soon gets iced right up, blocking off all airflow and the car stalls. If you jaz the gas petal it keeps running and the ice is cleared of the blades.

Worst around 40F +/- with high humidity. Add some methanol to your fuel (methol hydrate) will help. ( gas line antifreeze.) So will using the factory heated aircleaner and
manifold plenum heat.
Aftermarket vortec intake manifolds have a water passage under the carb plenum that you can plumb into the heater water hoses to get some plenum heat for quicker warm up.

Once the car gets heated up from engine heat the problem dissapears till the next morning with the right weather conditions that allow carb iceing.

 

hey james i have been meaning to ask you about your fuel mileage with your new engine, as i am doing the same engine swap. I am going to use a larger carb but if that provides horrible mileage i will resort back to what gm ho deluxe had with it. sorry about jacking the thread. Ryan

 

Hey, Ryan,

I'm not sure what the city mpg is, but on the highway I've been getting 18.7 or so, which is quite respectible, I think. Compared to my previous motor, a modded LG4 (cam, intake, dual snorkel and L69 exhaust) which got 24 on the highway, the HO is a beast--I wouldn't consider going back because the HO is just too much darned fun. By the way, I'm content with carb.

JamesC