Thermostat Ignition Fast Idle

Electrical & Ignition

  1. AJC

    AJC Member

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    Are these part or the thermostat ignition fast idle? There not on my vacuum diagram. If they are it's just switching from port to manifold vacuum right? There are 2 of them. 1 has 3 ports the other has 2.
    IMG_20190514_192750818.jpg
     
  2. Davea Lux

    Davea Lux Senior Member FCBO Gold Member

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    Those are ported vacuum switches. One of them is usually hooked to the vacuum diaphragm on the distributor so that vacuum is supplied to advance the timing once the engine has warmed up. The other ported vacuum switch is usually hooked to the EGR valve so that it does not open until the engine is warmed up. This was done to prevent manifold detonation, farting back thru the carb. The vac diagram under the hood or in the FSM should show the proper hose routing. The single lug sensor on the water pump housing is hooked to the temp gauge or the temp idiot light. Most mopars of this era had a fast idle cam on the carb that was activated by the closing of the choke. The choke is full closed on a cold start and the cam is hooked to the choke and deployed with the closed choke by a small linkage rod. As the engine warms up the choke relaxes and the fast idle cam is disengaged.

    Dave
     
    Last edited: May 15, 2019 at 4:56 PM
  3. 71NewYorkMan

    71NewYorkMan New Member

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    Your picture shows a two port version. This is for the EGR system as Davea Lux stated. (These were also used for air injection pump systems). The three port one is the Thermal Ignition Control (TIC) about which you asked. If you post the year, engine size, and ignition type (electronic or leanburn) I may have a vacuum diagram for you.
     
  4. AJC

    AJC Member

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    My vacuum line diagram shows the egr hooking up to the one on the radiator. Its a 76 440 no lean burn, but is a ca emissions engine.
     
  5. 71NewYorkMan

    71NewYorkMan New Member

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    I don't have anything for a 76 440 in my collection, but I did find a reference to a couple of different 75 versions on this site:
    http://newyorkeronline.org/m-r/engine/VacuumRouting/Non-ELB.jpg
    http://newyorkeronline.org/m-r/engine/VacuumRouting/1975.jpg
    (Thanks to @commando1 for the reference)

    Hopefully this will help with the TIC. EGR vacuum routing remained fairly consistent from 75-78, with one or two 2-port switches. Does your engine have two switches on the engine, and one on the radiator?
     
  6. AJC

    AJC Member

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    Yes 2 on the engine one on the radiator. So now that I know TIC stands for Thermal Ignition Control I see how its routed. If it doesn't hurt performance; is it worth putting it back or was it just emissions related.

    IMG_20190221_161950462 mod.jpg
     
  7. Davea Lux

    Davea Lux Senior Member FCBO Gold Member

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    TIC is primarily a delay mechanism for the vacuum advance. I would route the vacuum advance directly from the throttle plate port on the carb to the distributor. The car will probably run better and get slightly better fuel mileage. Do you intend to keep the EGR valve and the smog pump? With ethanol blend fuels, the EGR valve will likely carbon up and eventually fail to close properly leading to poor engine performance. From what I could see on the photos, it looks like much of the emission stuff is already disabled.

    Dave
     
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  8. 71NewYorkMan

    71NewYorkMan New Member

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    Yep- TIC and EGR systems can go away without any concerns.
     
  9. AJC

    AJC Member

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    None of the emission stuff is plumed up. Air pump has the belt unhooked. Initial timing is set at 12° and is ran off manifold vacuum. The EGR is in place with no lines to it. Should this be removed and caped or left like this? I need to get the evap system set back up along with the stove pipe to help with winter starting.
     
  10. 71NewYorkMan

    71NewYorkMan New Member

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    If the EGR valve itself is seating well (thus not leaking into intake) you can leave it be. Any doubts- remove and blank it. The evap canister and purge system won't affect MPG or performance, so getting it functioning again won't hurt. Running the distributor from manifold vacuum defeats the intended purpose of the vacuum advance- a gradual increase of advance curve (in conjunction with mechanical advance) which affects economy and throttle response). (This is a lengthy subject matter which has to do with basic combustion principles). The Heated Inlet Air System (stovepipe) is definitely worth fixing. It requires a functioning thermostat on the air cleaner as well as the stovepipe and associated tubing. The air pump was required for proper catalyst operation. If you no longer have your exhaust cat, it too can go away. (If you still have your exhaust cat, the chances of it being functional after 40+ years are nil). One concern with all of this- Some states do not forgive emissions systems requirements even for antique vehicles. I am not familiar with statures in Minnesota. Food for thought before you remove/bypass all of these systems.
     
  11. jct

    jct Senior Member

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    High flow cats are the way to go if need be
     
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  12. AJC

    AJC Member

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    We have no emissions tests or even an inspection here in Minnesota.

    I thought ported vacuum was another emissions related thing. There are a lot of opinions on weather to use ported or manifold vacuum for the vacuum advance.
     
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  13. 78Brougham

    78Brougham Deplorable FCBO Gold Member

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    Most all Mopars run on ported vacuum even before emissions were even a consideration.
    My advice is to disconnect the vacuum advance, set your idle speed and timing to spec. Then hook your vacuum to ported vacuum. Your car will run a thousand times better. Brighter minds than mine on this forum can explain on how the advance curves in a distributor work better than I, just ask.
     
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  14. 71NewYorkMan

    71NewYorkMan New Member

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    Not emissions related. EFFICIENCY related. Not opinion based, SCIENCE based (Physics of flame travel, engine speed, volumetric efficiency, on and on.)

    True for all cars in general. Proper advance curves for street driven engines are (were / will always be) important.