What is this "sender" ?

I try to see where the two vires go but i can't follow them .. But i've found this wiring and the position of the thermal switch is exactly as mine. But what is the function of this "modulator" ?

 

It's well a part of this "modulator". I found this on http://forums.vintage-mustang.com/v...549-distributor-modulator-system-70-351c.html

And i've also the "speed sensor" on the speedometer cable, i'll put a pic tomorrow. Nobody here can understand what what this sensor on a car without cruise control ! Now i know ...

 

I thought it could have something to do with your hesitation problem once I saw the pic diagram. But it shouldn't be too hard to remove it and replumb the vac to go with a Pertronix setup.

 

I compared my underhood and underdash setup with the pic,but maybe that pic isn't exact for a '73. Anyway,the PVS Valve on mine is attached to a metal extension of the heater hose. The larger vacuum-type hose from the PVS goes to the base of the carburetor next to the left side idle mixture screw. The smaller hose goes to a device next to the EGR. That device has wires going somewhere,maybe to the speed sensor. The distributor gets its vacuum only from the pipe at the right side of the carb base (no VDV). The red box underdash above the steering column doesn't seem to have had any vacuum hose attached, but I still think it was wired to the ambient temp sensor (which I haven't seen). Anyway,since the whole arrangement is not factory-correct,maybe some of the ways it was changed are wrong. Or maybe the vacuum from the carb base is allowed through the PVS when the thermostat opens to go to the device next to the EGR,and with the speed sensor,controls the EGR.

 

Time after time i think i follow the routing and components of this "modulator" device. I found a fitting on the Autolite carb which wasn't on the manual. From this outlet ther's a small tube which ran along with another (coming from "T" fitting near distributor) and go through the firewall, i suppose, to the "black box" modulator that i can't seen even with dash pas removed ! Here are some pics from my engine. Red line comes from carb base, yellow line from T fittin g (so from intake manifold)









The speed sensor on the speedo cable

 

Since EGR opening can affect idle (even stall the engine) or cause misfiring at cruise, this would explain this unit's reason for existing. Combining spark control and EGR rate predates OBD I by over a decade. Too bad it didn't work well enough.

 

I've no EGR on my car. The modulator works as only retarding th sparks to have a hotter temperature et better burnt of fuel when some speed and external temperature are reached. http://www.autozone.com/repairguide...ulator-Dist-O-Vac-System/_/P-0900c15280053ca7
The complete booklett is there, 25 pages (pics can be elarged) http://www.fordification.com/library/main.php?g2_itemId=2324

Note also that




So 'ill soon plug some lines... I haven't also the dual diaphram vacuum advance on distributor so even if the system is in working condition it can do ...nothing

 

You wanted a better pic, Phil so see if this one is better for you:

 

Sorry about the shadow at the bottom. I attempted to move back before snapping it. The carb in the pic looks to be a Holley/Motor craft 4300 carb.

 

Here's a few more pics, just in case something can help someone:

 

Thanks for the pics, my system is exactly like the first pic below (except i don't have neither a dual diaphragm vacuum advance, not the correct distributor for this, on my car ).
Where i must put the distributor vacuum hose ? At the fitting on the intake manifold (where is the hose to brake booster) or rather at the carb base fitting ? I think it's the second proposal, see my schematic at the bottom.
My carb is an Autolite 2100.

Actual system (i've found the schematic in the "engine" volume of the '70 manual)






What i'll do

 

Yes. You have it correct. The distributor advance vacuum source is in the base plate on the passenger side, up front.



This is a 2150, but the basic items are the same. This port does not allow vacuum at idle; only at part-throttle to wide open throttle (WOT). This is where you hook up your distributor advance; if you were to install a dual-diaphragm advance unit, the retard (vertical nipple) goes to manifold vacuum.

 

Why agonize over this obsolete, probably non-functioning emissions device?
Me? I'd disable it all. You'll have better drivability and probably better fuel economy as well.

 

It'd sure be nice to "disable it all",but EGR,ignition,speed sensor,& various vacuum devices are so interconnected,how could you do it? On mine,the distributor vacuum advance comes direct from the carburetor,but the ignition wiring from switch to coil is all deeply buried underdash and connected to goodness knows what!

 

42A above is my setup. The "amplifier" seems to have suffered a burned resistor. Note that this "amplifier" is the one without any vacuum hose going to/from it. I am not sure if the EGR system is working!