195.6 OHV cooling system...

Quick Question,should i drill one or two holes in the T stat?and use 180 or 195 degree t stat?And 50-50 coolant mix?water wetter?

it is hot tempered,but then agin the water pump was going out,well see how it is now that i got a new one.

Remember on the older sixes and some V8 engines the heat selector should be in the high heat position to allow the refill of the cooling system to work its way thru the heater core.  We started th 2011 Hot Rod Power Tour going from Denver CO to the start in Detroit MI. About 75 miles into the trip the temp started rising.  We had refilled the cooling without opening the heater core.  Must have had a bubble.  We turned the heat up and stopped for 15 min.  Never had a problem from them on.  4000 mile trip, Denver to Detroit to Dallas to Denver.

raysinvegas wrote: Tom, could you repost the other mods to the cooling system? I have forgotten what they are besides the extra holes in the thermostat.

It's http://www.wps.com/AMC/195.6OHV/Head-cooling/

I need to update the page -- i think most of that work (the bypass hose etc) is completely unneeded. I am pretty sure that simply drilling a large-ish hole (say 1/8 - 3/16") in the edge of the thermostat, and orient the hole towards the radiator, is enough.

The real test requires no test gear -- with a COLD engine, start and idle it. Put your hand on the head where you can, and on the thermostat pod, and radiator top tank... on a 232/258, they all warm up more or less at the same time. On the 195.6OHV, the head sometimes/often/always(*) gets VERY hot MUCH sooner than the pod/tank.

(*)I was hoping someone else would do this test and 'report back'... because not every single OHV has this problem i don't think, and i certainly haven't tested any others. It might be that "most" or "many" thermostats leak a tiny bit -- which would be totally harmless! -- and that's enough to solve the problem "most of the time on most cars". 

American Frank wrote: ...While ethylene glycol lowers the freezing point & raises the boiling point of coolant,  it also has a somewhat less efficient coefficient of thermal transfer, so a given engine will tend to run warmer with coolant-mix than it would with plain water;  but then there is the freezing / corrosion issue.

Strictly speaking, the lowered heat-capacity of mix won't affect the operating temperature of the car, instead, it will reduce the capacity of the system to pull out heat, but so slightly i can't imagine any situation it would matter in.

The efficiency of heat removal depends on the difference in temperature inside (coolant) to outside (air). So in fact, the hotter the engine gets (or colder it gets outside) the better the radiator works. Remember that the cooling system is a *closed loop* -- the thermostat isn't wide open, in fact it's probably mostly closed most of the time.

A less-efficient coolant might mean a microscopicly more open thermostat for a given engine temperature, but it will still regulate at the same temperature, regardless of the coolant type.

You don't want to suck ALL of the heat out of the engine! It wants to run at a more or less constant temperature (for various reasons) which is why no-thermostat is a terrible idea.

HERE'S THE POINT --

If you're at the point where the engine is producing more heat than the cooling system can remove, THEN  (1) you're in trouble! (2) this is the point where the heat capacity of the coolant comes into play. But! even that doesn't really matter! It just means a very slightly higher inside-to-outside temperature difference. Another way to say it is, under these conditions given a constant outside (air) temp for a specific overheated engine condition, the engine temp will be a few degrees higher. BFD, the radiator STILL works better with higher temperature differential.

It is obvious to me, that this isn't the place to worry about -- a handful of degree difference at the point you're overheating -- but to prevent overheating in the first place.



Edited by tomj - Aug/06/2012 at 5:30pm