What about the "yoke seal" on the bottom of the hood, which seals the bottom of the hood to the core support? Is it there? What about the radiator cap?
YES! DO ALWAYS check Romper Room Engine Cooling fundamentals like these!! If the yoke to hood "gasket"
Before you spend money on a fan and its needed mechanisms, pop out the freeze plugs and wash the accumulation out of the block's passages. ANY older car can benefit from that, I suspect.
Sho' Nuff! I've given a couple thorough block enemas to my 383s. The one I'm running now was only modestly scaled in, while the boat anchor candidate had SEVERE insoluble deposits in the water jacket. I recommend drain snakes, pneumatic chisels, pressure washers and strong vaacuum cleaners all to achieve a CLEAN water jacket. then replace the expansion plugs with good brass, or, if working in situ on those plugs behind the motor mount brackets, expandable copper plugs. The rubber plugs will do for several years in a pinch, so long as one remembers they're present.
I concur with the clutch fan and fan clutch upgrade. Best of both worlds.
First thing I did to Mathilda's setup, though the original 6 blade 18 inch direct drive fan pulled plenty air that first hot summer, and worked admirably at the cost of the torque required to spin it. There was NO SHROUD on that original factory setup, and from what I saw in period nomenclature, this was common with that fan. I replaced this with a 20 inch 7 blade clutch fan, sans shroud, that did as well but no better.
Seems like the center mark on the gauge is about 200 degrees F, with the red zone starting at about 260 degrees F? Remember that a pressurized 15lb cooling system means the boiling point is raised to about 260 degrees F at sea level, so anything under that should not cause any issues. I know, it looks "like trouble", but really shouldn't be "trouble".
Right on! This is why I set my cooling fan mark at 200. One can run all day at this temperature. Its warm enough to boil volatile alkanes out of the lubricant, but not so hot as to dangerously thin the stuff. Watching oil pressure, I find mine get's under 10 psi at idle over 215F, so I like to keep the engine coolant temperature between 200-210, though on a hot highway, 220 does fine. In fact, i like to run her up on a good I-19 run here to boil more crap out of the crankcase. I run a 33% ethylene glycol summer mixture for coolant with a "wetter" which does very nicely for the 383 and my 225.
I've seen several "overheating" threads in the past month. Gauges reading about 220 degrees F, which might be a little bit warmer than normal, but not near "overheating" levels.
Just for general principles, you might try and locate a "Robert Shaw"-type thermostat in the 180 degree F variation.
I warn you ALL here: Holley/Mr. Gasket is a sino-copy of the Real Deal. I tried 2 of these. They work through one season. The original RobertShaw lasts through multiple seasons, with fluid changes done twice yearly. FlowKooler sells them, and I guess they own the patent now. I prefer the Old Stuff, and horded a lifetime supply. Knowing how finite such stocks are, I'd recommend first FlowKooler, and then Mr. Gasket as a distant second. I see other copies, but haven't experimented with them.
Seems like Edelbrock of Holley now sells them? Mr. Gasket brand? Not inexpensive, but what Chrysler used back then, generally.
Just some thoughts,
CBODY67
I pointed out to a certain person that this was indeed the production line standard from Chrysler, showing the FSM, but some fools insist on a Flat Earth. I also have tried a couple brass poppet thermostats with decent result. As a rule, those which open nice and wide at the designated temperature, permitting maximum flow serve us best.
