So I have 250 6cyl in my 75 comet, the day I bought the car she ran fine for most of the way home even with the engine light on.. Until I got on the open highway and it started stalling. We pulled over the old man took a look and saw a few wires loose on the distributor cap pushed them back on and away we went I did not see the issue again for another week... Until of course I went for some highway driving. Sometimes it would happen even jusr driving around town I couldn't go anywhere, it would stall and stop. Now it seemed on the days it would run perfectly were warm sunny days, and I haven't been able to test this theory because we've had 3 straight weeks of horrible east coast weather, and the car doesn't make it out of the yard. Now that I've winded myself, bottom line is, I got a few opinions and I'm told that its my carburetor freezing and I nEed a heatshield fabricated and that's the only issue. Can anyone shed some light on this ?
My '74 250 came with a heat shield. Its function is to keep the carburetor from boiling...not freezing.
I suspect I had carb icing one cold, damp day with the Holley 600 on the 302. I barely made it home but no problem the next day. Not sure if the exhaust heat paths on the Edelbrock Performer intake have been plugged and there is a 1/4" insulating spacer under the carb. Changing the 180* thermostat to 195* helped with a hesitation problem and might also help avoid icing problems. Some day the intake may come off to check the exhaust heat paths.
Use to see it a lot. The old cars even had a manual flapper on the snorkel to switch summer/winter. It directs heat from the stove on the ex. manifold to the breather. It got replaced with a vacuum servo and a thermo switch. Without the warm air carbs can start to ice up around that 0 Celsius mark when the air is damp. It usually effected low speed circuits the worse though as the ice would cover the bore of the carb. Stalling was usually the first symptom as the idle circuit was froze over. IF you shut it off for a few minutes the heat would rise from the engine and melt the ice in the carb and your good to go for a short run. Then it freezes again. These old cars really need a heat stove for cold damp weather. http://en.wikipedia.org/wiki/Heated_air_inlet I think this is a GM but you get the idea. The lower inlet goes to a flexible tube to the heat stove on the exhaust. The vacuum servo would be connected to a hose that goes to a thermal vacuum switch.
Ill post a picture up in a bit, but I have a pipe leading from my breather back to the carb to circulate the warm air back. Right now so that air isn't flowing into the card I have clothespins holding the valve shut and so that the warm air is going directly back to the carb
I guess I won't post a picture up, I don't have the permissions for that, but does anyone get the idea?
