Winter is here and the carbureted vehicles that had a great lean burn turn in them are running very badly on start up.
Right now the air cleaner just draws warmed air from under the hood, it warm up eventually after everything else is hot. With the air heater tube going between the exhaust manifold and air cleaner I can have warm air less than 30 seconds.
The factory air cleaner is set up to run warmed air. All I have to do is hook it back up.
The way GM did it there is a pneumatic thermostat that opens and closes a flapper on the air cleaner intake tube. So it would go back and forth between 600'F air and cold air. You cant tune for that.
So I found a use for my
http://ecomodder.com/forum/showthrea...ake-27400.html. Instead of running raw scorching hot exhaust manifold air to the air cleaner I will temper the air with this. Then the engine will have warm air that is about the same temperature all the time. I can tune for that.
Only problem is this thermostatic valve was built for a 1.6L gas engine, not the 7.4L that its going on.
So I will need to retain the cold air function.
I have a small 3 way vacuum solenoid valve to control this with.
I figure I will run the common port to the flapper valve actuator.
Run the normally open port to a vacuum source, likely a tee on the distributor vacuum advance. I figure this will be how its ran roughly 99% of the time.
Then run the normally closed port to atmosphere.
That way when the solenoid is deenergized the flapper valve in the air cleaner will actuate allowing in warm air, power on will close the flapper valve and allow full cold air to the engine intake.