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Factory Tach accuracy

Big O

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Currently have 72 Dodge Charger Rally w/factory tach (rally dash) and the tach works, but is not reading correctly, shows about 750-1000 RPM more than I know it should be and sometimes it will stick. I need to start trouble shooting and was looking for some suggestions on where to start?
 
If it sticks it needs a rebuild, thats a mechanical issue. They do need calibration sometimes, unfortunately sounds like it needs to be sent out.
 
Some aftermarket ignitions do not drive correctly or at all in some cases. These guys should have what you need. MOPAR Products
 
I have a 340 Challenger Ralley. The tach isn't very close. I use a shift light when really hammering on it.
Doug
 
I’m not sure if applicable as late as 72 but I put a new, modern circuit board in the sender for my 66 Satellite console tach. It has an adjustment screw to use with a calibration tach to fine tune it. I adjusted it to match an Autometer tach and it stays with it. Only problem is looking down on the console tach it from my eye height, the needle at low rpms appears to read a couple hundred rpm’s low against the scale on the face due to the angle. Due to the angle, at the upper end of the rpm range it would also tend to read high. Console tachs were not one of Chrysler engineers better ideas.
 
Thanks guys for the information and website. That gives me a good starting point.
 
The real time tach kit is a winner, my factory tach was way off, installed the RT insert and it is dead nuts on the money. MSD Magnetic pickup distributor and Rev-n-nator controller. The sticking issue could be another problem on top though.
 
I still have 2 holes in upper dash where a Moroso mechanical tach sat from the late 70’s. Very accurate.
 
Why we installed aftermarket tachs & gauges back in the day ad infinitum.
When i had my 71 Hemi GTX car, i purchased it with the SUN Tach, on the console.
Sometime early in my ownership, i decided to install a factory tach, in the instrument cluster.
Surprisingly, they were always close to one another, in their readings.

GTX Interior Picture (Small).jpg
 
When i had my 71 Hemi GTX car, i purchased it with the SUN Tach, on the console.
Sometime early in my ownership, i decided to install a factory tach, in the instrument cluster.
Surprisingly, they were always close to one another, in their readings.

View attachment 1382648
you had an inviolet/or blue , white interior, 4spd 71 hemi GTX ?
 
InViolet.
Owned it for 28 years.
When i was in the Air Force, at Mather AFB, a B-52 Navigator Captain was finishing up his training, and had it for sale on the base "Lemon Lot" as we called it.
Back in the dinosaur days, would you believe i got it for $2,950.00 dollars.
Jim V.
hemi71x
 
InViolet.
Owned it for 28 years.
When i was in the Air Force, at Mather AFB, a B-52 Navigator Captain was finishing up his training, and had it for sale on the base "Lemon Lot" as we called it.
Back in the dinosaur days, would you believe i got it for $2,950.00 dollars.
Jim V.
hemi71x
Absolute wow. What happened to the car ?
 
Absolute wow. What happened to the car ?
I sold it off to a well known, big league collector, down in Long Beach, Ca.
He had it in his collection of cars for probably 10 years or more, but i never really kept track of how many years that he had it.
A couple of years ago, i found out that he since has sold it off to another collector, a dentist, in middle America somewhere.
That guy put it up for auction at one of the Mecum auction cities, 2, 3, years ago, but didn't sell at his reserve price.
Don't know if he still has the car, or since has been sold off privately, to someone else.
The car has been in numerous magazines throughout the years, when i still owned it, and after.
When i purchased the car, i never knew that it was one of 11 1971 Hemi GTX, 4 speed cars built.
19 others were automatics, so 30 total.
Now in my old age, the selling price that i got for it, is my living on money, in my old age, before i take the permanent dirt nap.
hemi71x was the personalized, California licence plate that i had on the car.
Just kept using that as user ID's, on all the web sites, all these years.
Something easy for me to remember.

Edit
Look here.
Found i had this bookmarked in my computer.

1971 Plymouth Hemi GTX | S160 | Indy 2020 | Mecum Auctions
 
Last edited:
I sold it off to a well known, big league collector, down in Long Beach, Ca.
He had it in collection of cars for probably 10 years or more, but i never really kept track of how many years that he had it.
A couple of years ago, i found out that he since has sold it off to another collector, a dentist, in middle America somewhere.
That guy put it up for auction at one of the Mecum auction cities, 2, 3, years ago, but didn't sell at his reserve price.
Don't know if he still has the car, or since has been sold off privately, to someone else.
The car has been in numerous magazines throughout the years, when i still owned it, and after.
When i purchased the car, i never knew that it was one of 11 1971 Hemi GTX, 4 speed cars built.
19 others were automatics, so 30 total.
Now in my old age, the selling price that i got for it, is my living on money, in my old age, before i take the permanent dirt nap.
hemi71x was the personalized, California licence plate that i had on the car.
Just kept using that as user ID's, on all the web sites, all these years.
Something easy for me to remember.

Edit
Look here.
Found i had this bookmarked in my computer.

1971 Plymouth Hemi GTX | S160 | Indy 2020 | Mecum Auctions
1670219747796.jpeg
Which is an understatement.
 
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