Thermostat for 1967 XR7 (390)

Cougar Community
1

Hello Gents,

What’s the preferred thermostat for my 1967 XR7 (390)? I notice that there are several temperature ranges available. My existing unit appears to be working but is way over five years old, and was on the car when I bought it. I’m doing a flush and a few upgrades so thought I would replace the thermostat at this time.
In addition, my original seat belts are very tatty and stained. I was considering replacing with more modern belts. Any recommendations?

2

The factory installed a 193 degree thermostat and IMHO it was the right choice. Drill a #40 hole in the new thermostat so the hole can vent trapped air when you fill the engine with coolant.

There were two sizes used in 1967 390’s depending on the build date of the engine.

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3

I believe mine was an early 67. Not sure how to check the manufacture date. Also, it’s always possible the engine might have been changed over the years. I don’t think so but who knows. Thanks for your help.

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The engine would have to be assembled earlier than the car. The car’s scheduled date is on the LH door tag. The VIN is also a good thing to tell the build date approximately.

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:+1:

6

Ok March 24 is several months after the change from large to small thermostats.

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BTW it’s near the end of 1967 production. The factory began to change to 1968 production on July 4 1967.

8

OH I apologize - March 24 is today’s date and my phone slipped that into your post. When I look at my computer I only see the thumbs up.

9

No problem, Thanks for your help.

Les

10

Motorcraft RT-1139 is 192 degrees, fits and already has the jiggle valve (no need to drill a hole in it). The jiggle valve should be oriented at the top when installed.

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Thanks for that tip. I wasn’t sure where to drill the hole anyway. I assume these thermostats only fit one way anyway. I appreciate the help. Les

12

You can install any thermostat backwards. The spring needs to be towards the engine and the jiggle pin at 12:00.

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13

Got it. Thanks.

14

Hello again gents,
Well I bought the RT-1139 in advance and of course according to Murphy’s law, it turns out (that now I’ve removed the housing) that I have the larger version (bigger diameter). I assume that it’s therefore an earlier model engine. Do you have a part number or type for a 193 deg. thermostat that will work for this engine? I’m trying to find something locally to avoid a shipping delay.
Thanks again.

15

The Edelbrock part number is 8605 Small Thermostat 195 degree

16

Oops you need the large thermostat which is eqiuvalent to the Tuff Stuff TFF-900195 Large diameter thermostat 195 Degrees

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17

That’s more like it! Confused me a bit there :thinking: Couldn’t find anything locally. They are all small diameter flange, so have to buy online. Thanks again.

18

Have freshly built (<3 hours run time mostly in the garage and maybe 25 total driven miles) 67 GT 390 w/C6 that is basically stock rebuild w/refurbished S intake and exhaust manifolds with the exception of the cam (Comp 268H).

Has original 390 radiator (cleaned, rodded and pressure checked) with replacement stock fan/fan clutch and shroud as well as water pump. The rebuilt C6 is plumbed into the built-in transmission cooler in the radiator.

I’ve also added a puke tank with purge tube for any overflow that exceeds its capacity but left the vented cap w/Lever release (also new).

I installed a 160 thermostat which after reading information above may have bee the wrong choice given the tightness of the engine bay (a lot of heat in there).

I also have replaced the radiator core support rubber seal for blocking the air from running over the radiator instead of through it.

The car never runs hot but hotter than I’m used to seeing with a 160 thermostat.

After warm up, it starts out where I expect at about 170-175 and then slowly creaps up to about 190-195 after about 10 minutes of driving around town where I’m generally steaming along at about 45 or 50 MPH between stoplights.

The temperature gauge is Autometer electric type (retrofit) with the sensor location same as factory. Have validated gauge indication with thermal temperature gun.

I’m here in Southern Arizona and need confidence in the cooling before I strike out on longer distance drives.

So, question is, will the195 thermostat be the correct choice for my needs?

Anything else in terms of lessons learned?

BTW - not a fan of electric fans so that isn’t where I’d want to go.

Thanks, Jim