Exhaust diverter valve open or closed?

In the fuel/exhaust section of the TSM there's a side-on illustration of the diverter valve, the one that sends the exhaust through the intake manifold while the engine warms.

Lever up - closed
Lever down - open.

But what is open or closed? Is it the exhaust or the diversion?

I ask because the lever on mine is always Up. It never moves, even though it's free to do so.

If it's going to stay in one position, I'd prefer a longer warmup and a free exhaust so the carb doesn't overheat.

So where does the lever need to be? Up or down?

Ivor

Haha.
Cunning plan.
But it has a single exhaust.

Ivor

the valve it controlled by a thermostatic spring . yes lever up is closed and as things heat up it open by weight of the pendulum lever

Another cunning plan is to remember that somewhere..... I have a remote point-and-shoot thermometer.

So, I start up and almost immediately the crossover is at 80F and rising. The exhaust pipe is nearer 60F.
Pretty soon, the crossover is over 100F.
Push the lever down, although it's free it doesn't want to fall by itself, now the crossover goes down to 70F and the exhaust is rising past 110F. After three minutes or so, I stopped.

I left it down. Not all the way down I don't think, it jams somewhat and I could probably tap it further. A bit of heat below the carb won't hurt.

Could be why the car didn't like to idle a long time in traffic. The fuel in the float chamber must have been near boiling.

Another little problem solved. The power of the forum.

Ivor

Edited by 990V8 - Jan/23/2018 at 2:07pm

Back in the day, AMC marketed an aerosol Heat Valve Lubricant for such purposes.