survivordemon
Well-Known Member
I have seen this on a few 71 A-bodies, what is it? The speedometer cable goes to it. Thanks
Can anyone tell me what this is?
- Thread starter survivordemon
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dirty white boy
50 yr old Juvenal delinquent
its a speedometer gear ratio box, to correct speedometer
It's an emissions speed switch...
survivordemon
Well-Known Member
What is it's purpose and why don't I see many of them? Everyone that looks at my car asks what it is? Thanks
Red's '72 Dart
Well-Known Member
I have one on my 72 Dart Custom. I also would like to know what it is called and its purpose.
Can I remove it or just leave it there?
Can I remove it or just leave it there?
yep, and I'm pretty sure it was a one year item, 2 years at most. Most owners cut the wire anyway.
This is right, only used for a couple of years. Thought it was part of NOX system
No sir, its just a centrifugal switch. It aint big enough to hold gear reduction or anything more really.
ScampMike
Despicable Damn Yankee
use it to activate your NOS!!! 
survivordemon
Well-Known Member
So if I change my transmission I can keep it?
If you wish. A plastic gear in the trans alters the speedometer cable speed. That plastic gear selected per rear gear ratio, and tire diameter. This centrifugal switch will still spin the same and speedometer will read the same.
Gm offered an adjustable speed alert that would buzz when you exceeded your preset speed.
In the late 70s I worked at a Holiday gas station in Minneapolis and we were the last stations to carry high octane premium gas.... so we saw a lot of muscle cars.. one was a 68 Camaro RS/SS 396 with 8k miles on it and it had the speed alert option. Along with just about every other option !
In the late 70s I worked at a Holiday gas station in Minneapolis and we were the last stations to carry high octane premium gas.... so we saw a lot of muscle cars.. one was a 68 Camaro RS/SS 396 with 8k miles on it and it had the speed alert option. Along with just about every other option !
Red's '72 Dart
Well-Known Member
Thanks for all the info guys!
I am going to trace the wire down, and see where it goes.
I am going to trace the wire down, and see where it goes.
?
Here's more info on the speed switch...
survivordemon
Well-Known Member
Thanks for all the help guys!
kaytbugsdad
Well-Known Member
My 75 318 Swinger had one of those........ I don't remember what they used it for, but it had something to do with emissions..... I probably still have it, along with all the other emissions parts I removed!!!!!
In 74 or 75 they came out with a "Fuel Pacer System". It is vacuum operated though I believe!
This was strictly NOX and likely just a Cal car or maybe NY as well.
This was strictly NOX and likely just a Cal car or maybe NY as well.
kaytbugsdad
Well-Known Member
Mine has an electrical connector on it...... I want to say they used it for the EGR, but I'm not sure......
Basically yes. EGR was developed to control NOX but was not introduced in 71. Later years combined all this "EGR" included and more to rob us from power and save the Earth. Today they have refined it to the point we have the SRT Demon with more power than we ever dreamed of in the 70's!
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