47-55.1 Original Heat/Defrost Box W/ newer Engine

[fauXGT]

Starting the original heater box restoral, and keep running into the info that the old systems are very low pressure....about 4lbs. I have found an aftermarket replacement core for about $300 that works with higher pressure systems, but has anyone figured out some sort of a pressure regulator for a modern 12lbs+ system to a old stock core? Can't find anything on the net other than getting directed to Mustang sites. lol.

[joedoh]

you couldnt change the pressure through just the heater core, even though the idea is a unique one. you are probably thinking of dropping pressure the way a regulator does for air tools, but this isnt air this is coolant, and the reason it is under pressure is to raise the boiling point of water. if you lowered the pressure in just the heater circuit, the temp of the water/coolant mix would be way over 212, even if it was only 200 in the engine loop. but there is no way to affect this change in pressure localized only in the heater core, it would be delta p (differential pressure) on BOTH ends, heater inlet and outlet, which would only let the pressure equalize between the engine and the heater core.

my advice? buy a heater for a tractor, new fan, new core, new valve, capable of high pressure systems and much more efficient. put the old cover on top. it wont cost anywhere near 300

[dsraven]

yeah, joedoh is right again, just replace the heater guts with something that fits nside the original heater housing so it looks stock on the outside. I had to do something similar for my boat heater. I went to red dot's site and looked at the dimensional charts and then the drawings to see how the tubes exit the core and what size they are. just bear in mind that the sizes they give are the core without the tanks so the actual outside dimensions are bigger. you could also try MEI, ATC or SPECTRUM's sites as well.

[47 Fasttoys]

OK, ill put in my opinions on this matter. The heater cores made in the 40s or 50s where not made any weaker then what was made later. I have built 3 of these trucks where I reused the original heater including my current daily driver. Just because the original system ran a lower pressure does not mean the heater core cannot handle a much higher pressure. If your heater core leaked before, it still will with higher pressure. I personally have had more issues with aftermarket aluminum core then any factory units. I currently have 185,XXX miles on my build and I would guess another 100,000 on the heater core. I have converted all three to 12 volt motors. I have used the original cores with a 4.8l, 5.3l and a 350.
Rob

[fauXGT]

The other issue I discovered is the Ranco heater thermostat.
Looking at all the pics I could find online, mine looked a bit different. I thought I had an internal temp sensor until I tore it apart. Nope. The little copper tube had snapped right at the bellows and is done. And apparently no one sells just that part...as far as I can find. "If that part is broken and the mysterious chemical/gas is gone... it's done, and the rest is salvageable for parts for other rebuidable stats." I was going to order the valve seal kit to rebuild it and get it functioning fully stock, but might just put the $10 seal part in, put in a manual coolant shutoff using the stock 'T' cable (for temp) and call it done. Looks stock but still functions as heat/defrost when needed, being will mostly be a non-winter driver (until I retire to Montana, which has the 4 seasons. Winter, winter, winter, and road construction).

[joedoh]

fasttoys is right, i personally havent ever used an old heater on a new engine, mostly because they are ub sych terrible shape to begin with that replacing every part except the core and the cover offends my frugality haha. i have only heard of people having the core leak or not surviving the pressure test at the rad shop. good advice!