[jhein]

I'm confused by the sending units on the intake. The smaller one on the drivers side appears to go to my gauge. I don't know about the other one on the passenger side. What does it do?

[25stevem]

I can say what that sender does, but what I can say is that it certainly is not a original type due to the type of slip on connector used.

It appears to be a single terminal sender from what I can tell from your photo .

[redhawk44]

Do you have an add on temp gauge and the factory temp indicator?

[jhein]

No, standard factory gauges. The one on the DS is a small single post sender. If I disconnect that one my gauge does not operate. The motor is not in the car now so I don't know what happens if I disconnect the other one which is a larger sender that has at least two and maybe three terminals, don't remember.

[Held for Ransom]

Passenger side is the TCS (transmission controlled spark) temperature switch, part of the CCS (controlled combustion system) circuit.

[jhein]

Originally Posted by Held for Ransom

Passenger side is the TCS (transmission controlled spark) temperature switch, part of the CCS (controlled combustion system) circuit.

Ah, that makes sense. I don't have that system operational. I think I'm still gonna install the sender and connect the harness just to make it look more correct.

Thanks for that.

[Joe's Garage]

If the system is functional it energizes the solenoid that allows full manifold vacuum to the vacuum advance when the engine is very cold - helping with the choke system and idle during warmup.

It also energizes the solenoid if the engine gets too hot either at idle or low speeds - applying full vacuum advance and increasing the idle speed to help with cooling the engine back down.

In addition to this coolant temp sender activating the solenoid, it is activated by either a speedometer cable switch (on automatic transmissions) or a switch on the 3-4 shift lever (on Muncie transmissions) to allow full vacuum advance only in high gear on automatics or 3-4 gear on manuals.

So that TCS solenoid is a really busy little solenoid !

[jhein]

Originally Posted by Joe's Garage

So that TCS solenoid is a really busy little solenoid !

That's what I'm learning. Seems like if there's anything on the motor that's vacuum, temperature or electric that you're not sure what it is, it's probably part of the TCS system. LOL.

[tjs72lemans]

Someone on here mentioned leaving that unhooked for better fuel economy and it was more of an emissions device. Anyone else have an opinion on that?

[Joe's Garage]

It will just give you full manifold vacuum to the vacuum advance if you use a stock carb.

With aftermarket carbs, most of them have a ported vacuum nipple/fitting.

[jhein]

After this thread, I decided to just use full manifold vacuum.

https://forums.maxperformanceinc.com...15#post6286915

[Formulajones]

Originally Posted by tjs72lemans

Someone on here mentioned leaving that unhooked for better fuel economy and it was more of an emissions device. Anyone else have an opinion on that?

Correct, it is an emissions device.
There is no real reason to not have vacuum advance working all the time other than emissions purposes. There is no down side to having it always working.

In fact, when I bought my 70 Formula from the original owner in California, one thing he had done early on was bypass the TCS system. It got better mileage and ran cooler in stop and go or slow traffic with vacuum advance working all the time. However when I bought it, it had to be emissions tested, and there was a sticker on the inner fender that stated "Vacuum advance must be disconnected at all times". That's something the EPA test facility put on there many years ago. So every year he tested the car he had to remember to unplug the vacuum advance otherwise it would pump more hydrocarbons (I think that was the result)

So I unplugged it, pulled in and had it tested, passed easily, and before I left the lot I plugged that sucker back in

[tjs72lemans]

Thank you.