65 273
On my dart, I can hear mine clanking when I let off the gas and let the engine slow the car down. Got that mopar heat riser sound you hear on all these old cars with the original exhaust Manifolds.
I seem to recall the 70's cars had an outer flap you could use to turn the riser. I havent noticed such a thing on my dart.
So no way I've seen to verify if it is opening all the way. Just knowing that when I hear the clanking that the car is warm and the thing is moving freely as needed.