Cliff....I assume ICO = Idle Cut Off ? Yes, I've worked on many a car with that system, but certain models would still pull fuel from the main-jet, sufficient to maintain running...some designs had both the air-dump solenoid and the idle cutoff. the Fords sounded like an asthmatic, when you turned them off
Interesting to learn that Sodium filled valves were around then....it was quite a novelty in the 70's car repair business and, having been cautioned against cutting them, I often wondered what happened when a piston broke a head off when the timing went.....removed a few bent ones from Fiat twin-cams, but the heads stayed on
still awaiting the answer .....and this is still the best thread on proon
Thanks!