Factory cruise

[1970Custom]

I've been slowly going over the '71 F-100 that I picked up (traded my '93 F-150 for it) and came across this...



I've been told that it's part of a dealer added cruise control. Only problem is that, if that is in fact what it is, the rest of the system is missing from what I've seen for cruise systems...

Any thoughts or information?

[fordman]

ive seen one of those on a dentside that had cruise on it.

[1971ford]

what does your turn signal look like exactly? i think it should have a twisty thingy on the end if its cruise control

[71murd]

That is a dealer add on cruise from mid 70's ford you cancan get most parts at ayard off a dent turn signal switch arm with set button and resume switch and you will need vaccuum accuater for throttle linkage also the brains

[FORDification]

Sorry guys....this has nothing to do with cruise control, although it does look almost the same as the cruise control speed sensor. Actually, is IS a speed sensor, but in this case it's simply an emission control device...or rather, one component of a system called the Distributor Modulator System (sometimes referred to as the Dist-O-Vac system).

This NOx setup only allows the vacuum advance to work under certain conditions. When the outside temperature is below 60 degrees or so the vacuum advance is allowed...when it's above that temp, the vacuum advance is only allowed when the vehicle is traveling around 30mph or faster. The hardware and wiring to do this varied from '70-'72 but basically you have a temperature sensor on the driver's door pillar, the speed sensor (pictured above) and a control module with a solenoid valve for the vacuum (found on the inside cab firewall by the steering column). The control module switches the vacuum source on or off to the vacuum advance depending on the temps and/or speed. This emission system is a 'tack-on' (meaning it can be easily removed) and was standard on some cars, Rancheros, Econolines and F-100 trucks with an automatic transmission and a 240-1V, 302-2V, 390-2V or 351-4V.

I've got a special 26-page troubleshooting manual on this setup that will be scanned and posted to the site in the near future. Until then, here's a scan of the setup:

[1970Custom]

THAT'S what the little silver thing is midway down the front of the jam, seen so many of them but never knew what they were...

Next question, is the stuff worth anything? This truck is almost all original (minus the tank being moved under the bed, the exhaust and the mirrors) with 130k. This is the first truck I've owned that I'm can't bring myself to screw with, I know the trucks aren't really worth that much but it's odd for me...


Also, would the system have something to do with the stumble above idle through all the gears (C4)?

[FORDification]

I can't imagine anyone wanting any of that setup....but if you you remove it, it sure wouldn't hurt to list it on E-bay, just for kicks. Don't hold your breath though on getting a bid. The only time I'd think someone would be interested in installing smog equipment would be for a concours restoration, and then they'd probably want NOS parts.

As for your stumble, why not just disconnect the system and see what happens? But I'm guessing it doesn't have anything to do with it.

[1970Custom]

I don't think it is either BUT I've never had this on any of my vehicles so I'm covering my bases...

[papabug71]

I would pull it & list it on ebay. Who knows, you might get lucky. Since your missing pieces, it would make more sence to pull the remaining pieces & try to sell them rather than try & hunt down the rest of the unit.

Its smog equipment after all !!

[Happy_Camper]

Any chance somebody has a part number for the two speedo cables on this system?
I'm thinking they *may* be just right for use when installing the later model cruise control speed sensor
Thanks!

[FORDification]

Just thought I'd let everyone know that I finally posted the book I was referring to to the site. This is a 28-page training filmstrip review book discussing the 1970 Distributor Modulator System.

1970 Distributor Modulator System Film Review Book

[mr_josh]

That is really cool, good work. NO one knows anything about that, everyone assumes that sensor is something to do with the dome lights (in fact, the nitwit that owned my truck before me had it wired to the dome light...) Bravo, sir.