Thermostat Housing Thread

Does anyone happen to know what the threads on the two ports on the thermostat housing are for a '60s 170/200? There is the barb fitting that the carb spacer/heater hose attaches to, and then a spot that's been plugged. I only have one thermostat housing, and it's on my car and filled with coolant. If anyone knows the thread size/pitch of both spots, it'd be helpful!

I'm confused. You are talking about two different things and neither one of them have any threads in them other than the pipe threads for hose barbs.
The threads in the thermostat housing are 3/8" pipe thread IIRC.

Yep, I am talking about two different things. I think the confusion is that I mis-represented the location of the carb spacer/heater outlet... it's on the water pump, not the thermostat housing.

In any case, both are probably pipe threads, and both could be 3/8" - but I have no way of checking them without draining my radiator, which I'd rather not do if someone can tell me what they are. If they're 3/8" NPT, that would be positively super.

You wouldn't have to drain much if any.
I don't think there's much coolant in the upper hose when it's cold.

There may not be much in the upper hose, but it will be the same height as the fluid level in the radiator and once the hose is removed all antifreeze higher than that new leak will come out the hole.

He would have to drain the radiator down to a level that is lower than the fitting he wants to check out.

Yeah, and that's what I'm trying not to do - yet. I'm going to have to do it at some point soon to install what I need to install - I'd just like to have the parts on hand before I dismantle. 3/8" NPT seems plausible, so that's what I'm going with. Got some fittings, a new heater core, and some hose incoming!

I guess my related question is how the heater in the car works, as my car doesn't have one at the moment. I assume the system is constantly circulating through the core, and it's just the door that keeps the heat out of the cabin, yeah? I ask because I am going to use the heater core "circuit" to take an coolant temperature reading from, and that'd be less effective if there is some sort of heater valve in there that blocked circulation. I'm assuming it must keep circulating, or the carb heater/spacer would be fairly ineffective.

CoupeBoy":2zvzsmpq said:

There may not be much in the upper hose, but it will be the same height as the fluid level in the radiator and once the hose is removed all antifreeze higher than that new leak will come out the hole.

He would have to drain the radiator down to a level that is lower than the fitting he wants to check out.

Click to expand...

Yah although it seems my coolant level always ends up a little on the low side.
It's really cold up here. -20C. I have to put cardboard in front to help the warming, often the thermostat doesn't even open up.

You probably already figured this one out sameguy, but it should be 1/2" npt...
http://www.mustangsunlimited.com/itemdy ... 1=18599+01

Based on the wrong description @ MU ("threads into the intake manifold"=bent8), it might be a HELP aisle item at the parts store, but DIY npt fittings work too.

Yes it should be a constantly circulating system based on your mention of a carb base heater (I forget what year the valve comes in, but pretty sure it's after the carb base heater delete).

You also might want to play with an IR temp gun to make sure you'll get an accurate enough read at the heater core. Shouldn't drop a lot, but the cooling effect of intake air at the carb base and the distance from the heater outlet on the side of the head (inlet is at the pump), could make a difference.
Good luck

"...if there is some sort of heater valve in there that blocked circulation...."

There's a knob on the dash...U push it in/pull it out & a cable goes thru the fire wall to open & close a valve mounted on the engine side of the wall that has the hose "in-line" mounted to it. It shuts off/opens the flow so just as U say it is constantly cerculating. Many loose the valve &/or the h. core (may B live in Fla or Cal, the sob.s) and just but the ends of the hose together. When U turn that same knob it starts a fan that blows accross the h. core. Some yrs U hadda lean down & maunally open a lill door. Other yrs a 2nd knob would open a door (as U say) that would switch the air stream from dash to cabin or "floor". Lot simpler (less expensive, easy to repair) than today's vac systems. We kept em running w/ "chewin gum and bailing twine" (till balin wire came out, even better!).