Water through Intake Manifolds
AJ, Did you mean to quote me or Lonnie?
I meant you,lol, Yeah I messed up
Assuming no headers;
If you put an IR gun on the manifolds at the ports, with a stock cam and proper ignition timing, and at idle, I think you are gonna find the temps at the exhaust ports is gonna be ~350*F or less. Some ports could be closer to 250*
Now,If your heat crossover was still operational, And the oil-shield underneath the plenum was NOT full of coke,then you could shut the engine off,whack open the secondaries and shoot the plenum floor. And I haven't tried it, but I am pretty sure it will be less than 240*F ... cuz if it was 240*F, or more, it would be heating the oil to the point of smoking; and the PCV would be inhaling that smoke, and it would be condensing on the back of your intake valves and plugging the ports up. Since you didn't mention this, Ima thinking the temp is below 240, maybe closer to 200/220 or so.
Now, when you put it in gear and start blasting down the road, if the heat-riser is working right that crossover is not gonna see a lotta action, because; a) the heat-riser is wide open, and B) the exhaust system is gonna be under a bit of pressure, keeping the shuttling to a minimum. And so the temp will be fairly stable and low, cuz additionally,the incoming fresh air is gonna cool that plenum off some, by process of evaporation.
But if your carb is inhaling hot underhood air that is being heated by the radiator and the exhaust manifolds, well put a thermometer in there and see how hot it's getting.
Now, if that airgap under the plenum, between the intake and the splash-shield is full of coke, then that coke, with a closed heat-riser,and a functioning crossover will become a heatsink, keeping your intake plenum hot all the time.
But with a blocked crossover, it will just maintain about whatever the water is doing same as what the iron intake is running at.
The bottom line is that the iron intake, with a NON-fuctioning system is only gonna run maybe 20/30* or so cooler, at or near idle and at PartThrottle, than if everything was working right.
BUT
You can reduce your inlet air temp from 200 or more degrees, to ambient by ducting some fresh air to the carb. That's probably more than a 100*F difference, maybe as much as 150*.
The lightest compounds in your gasoline want to evaporate at or near 85/90*F. Great for cold starting. Not great when you shut a hot engine off, and the carb is surrounded with hot air that is at or near 200 to 300.
