What is this??

Texican

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I have seen these on several old Cruisers, this one came off a 68 or so Pig.....it is connected to the transer case via the speedo cable and the 2 wires are routed with the cable to somewhere in the dash loom.........So I was jacking around with it, gorunded one side and hooked the other into the VSS input on the TBI conversion I'm doing, and it reads on my Snap On scanner, seemed to read fast. I spuin it with my hand and it bounced around between 50 to 120 mph......

We'll see if it works.........
Mvc-010f.jpg
Mvc-011f.jpg
 

Landpimp

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hmmm, not on a 55 but on a 75-76 fj40 there is the thingy that goes inline with the speedo cable and is a emission counter thingy a ma jiggy
 

Texican

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Landpimp said:
hmmm, not on a 55 but on a 75-76 fj40 there is the thingy that goes inline with the speedo cable and is a emission counter thingy a ma jiggy

I have one of those that came off my 40, have you ever took the cover off?
It has an odometer just like the one in the dash, mine reads 83455........

So WTF did this little demon do on the truck you pasted the diagram?
And don't just type detects speed........ :D :D :D
 
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As I understand it, the speed detector tells the speed marker "computer" when to adjust the vacuum retard according to the speed via the VSV switching valve for a retard distributor system!

Here, I'll quote from the manual:

Speed Detector

Speed detector, installed at the speedometer cable on the transmission side, is an A. C. generator which induces voltage proportional to vehicle speeds. Voltage generated at the speed of 37.5 mph is 6.1 volts for F....Vacuum switching valve is actuated by the switching operation of the speed marker when vehicle speeds exceeds ... 14 mph (F engine) and leads atmospheric pressure to the positioner diaphragm at the carburetor. As the accelerator pedal is further depressed, the positioner is pulled away from the diaphragm by a return spring, and its lower end moves downward to a set position, which keeps the throttle valve slightly open at deceleration. In this way vaccum underneath the throttle can be reduced. This in turn retards ignition timing in order to compensate for loss of engine braking effect which is caused by an open throttle valve....concurrently, intake manifold vacuum is let to the retard chamber of the distributor diaphragm unit....Further deceleration of vehicle to below 14 mph (F) will cause the vacuum switching valve to return to the original position...."Toyota Improved Combustion System" reduces emission of unburned hydrocarbons and carbon monoxide to minimum.


That's edited and rearranged from the manual. Gives you the idea. My truck came with the VSV and the Speed Marker (don't really know if it works). I had never seen the speed sensor, since it had gone missing along with the speedometer cable.

If you are highly motivated I can scan and send you all of the pertinent pages and text, with the circuit diagrams and so forth for the Speed Marker. Here's another more functional schematic.
TICS (Small).jpg
 
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Your quick

How did you dig that up so quick? Do you have all the manuals? I knew what it was, but did not have the info you do....I am impressed ;p
 
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Bill, I have the manual at home here. The first diagram I've posted before, so I called it up and reposted. The other I scanned in. If you or anyone wants the pertinent pages, again, I'll be happy to scan and send it.

I have 2 VSVs and 1 Speed Marker computer that I'll never use, because I've gone to a non-USA vacuum advance system. So if anyone is desirous of those parts they are welcome to them. :D
 
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Can someone tell me what I'm doing to my truck then and what's the best way to run it. I have exactly what's described by IDave. My speedo cable is one peace though. the vsv also went away with the charcoal canister when I got a newer gas tank. Now my dizzy which I assume is retard is plugged in below the carb on the drivers side (vacuum line at bottom of carb). I set timing at 7deg without dizzy plugged in, when I plug it in it retards timing to about 0. should I unplug dizzy vacuum, replace dizzy and carb (to get ported vacuum), or what is my best least expensive option or at least your opinions. Thanks for the info.

Les
 
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jikser, what year is your truck? I tossed the retard dizzy I had on my 73 and got an early one, I think 68/69, which is advance. I sent my carb to Jim Chenowith for a rebuilt off the LCML. He ported the carb for advance vacuum. I have run that setup for 5 years + now. I also use a Petronix setup You can see it here http://www.wejacks.com/pertronix/index.html
 

65swb45

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jikser said:
Can someone tell me what I'm doing to my truck then and what's the best way to run it. I have exactly what's described by IDave. My speedo cable is one peace though. the vsv also went away with the charcoal canister when I got a newer gas tank. Now my dizzy which I assume is retard is plugged in below the carb on the drivers side (vacuum line at bottom of carb). I set timing at 7deg without dizzy plugged in, when I plug it in it retards timing to about 0. should I unplug dizzy vacuum, replace dizzy and carb (to get ported vacuum), or what is my best least expensive option or at least your opinions. Thanks for the info.

Les
If your diaphram is pointing towards the rear of the truck, then it's prolly vac retard. Plug it off until you can afford to get a vac advance distributor.
 
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Thanks for the inputs, it is pointing towards the rear of the truck, only one vacuum fitting. I'll try it both ways, plugged and unplugged and post how it works. I know the engine gains about 100rpm when unplugged. Ideally want JimC and advanced when I can afford it.

Les
 
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