1 hour ago, siteunseen said:

https://www.ztherapy.com/technical_stuff/spotterguides/zcar/240spotter.htm

The 72 intake was water warmed to help atomize the fuel faster when the engine was cold.

Which would promote better and more complete combustion of the air/fuel mixture, resulting in lower exhaust emissions.

Once the engine is at operating temperature, the  thermostatic valve closes and blocks the flow of coolant through the manifolds. At that point the engine is warm enough to more completely consume the incoming fuel.

 

Edited August 1, 20222 yr by Racer X

Racer X

Thanks for the link.  Good to know.  

Having said that, I'm left unsure as to whether the coolant line through the manifolds began with the 1972 model year, or with the so-called Series 2, mid-1971 cars that among other things removed the rear hatch lid vents.  Any idea?  Reason I ask is that I have a manifold with the cooling line currently on the car (4/71), but two others, one of which does not have the line lying around taking up space.  

Thanks

The "series 1" cars have the water through the intake manifold, just not into the carbs. The picture posted by @siteunseen (the librarian) of the 2 intake manifolds shows the water line on both the early 70-71 cars (4 screw carbs) and the 72 cars (3 screw carbs) the big difference is the 72 manifold has an additional loop in each carb mounting to route water through the carbs themselves.

That's what I was thinking too. I I rember a thread about the difference in phenolic spacers. Some have holes that let coolant into the carbs if I remember right. You could go to zcardepot.com and see the different spacers?

This may be it...