1969 Road Runner tach

The factory tach is reading much too high. Is there a simple DIY adjustment to make on the tach from under the dash, or do I have to take it out and send it to someone. If the latter, who is recommended?

Thanks in advance.

Standard dash or Rally dash? I don't think it really makes a difference, there are no adjustments that I know of. There are just connections for battery, ground and tach signal.

The tach in my 69 GTX reads high by over 1000 rpm also.

If you are running the factory tach and have installed an electronic ignition, it will be out of whack until you convert the tach to electronic internals.

Standard dash & still running points. At idle, it's reading about 1,200 & around town driving about 3,500- 4,000.

Richard Cranium said:

Standard dash & still running points. At idle, it's reading about 1,200 & around town driving about 3,500- 4,000.

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Shannon at Redline is a good one and probably my favorite. I have also used Instrument Specialties before with no problems.

Instrument Specialties is a mass production shop in my opinion. I sent one cluster there and it returned in so so condition and the tic toc tachometer had to go back 3 times before it was finally fixed. Red Line gauges for my money.

Jerry Hall said:

Instrument Specialties is a mass production shop in my opinion. I sent one cluster there and it returned in so so condition and the tic toc tachometer had to go back 3 times before it was finally fixed. Red Line gauges for my money.

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Yeah, it's been 15 years since I have used Instrument Specialties, so don't know what they are like now.
Everything since I have used Redline for. Big plus to me is that Shannon is a Mopar guy and is always available to talk.

4mulas said:

https://www.rt-eng.com/index.php/RTE_67-74_Tach_kit.html

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Have you used this?

I have the rte conversion board on my tach because I went to electronic ignition.
Mine is over 20 years old and works well, only has one adjustment, I think the new ones have 2 adjustments.
Mine is pretty accurate but doubt it's perfect, the tack itself is still over 50 years old.

Richard Cranium said:

Have you used this?

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For my 66 formula S b-Cuda yes, not for our cars. I was happy.

The re-pop electronic ‘factory style’ tach (no longer available I think) in the Belvedere works accurately above 1000 rpm. When the car is idling at 800 it reads 550-600.
This is the one I have (not from year one but as many of these parts they are all the same sold by many) https://www.yearone.com/Product/chrysler-b-body/tac120#prettyPhoto

This is classic industries one I think they have in the works. Been saying coming soon for quite some time now. I imagine the guts RTE sells are the same or similar. https://www.classicindustries.com/product/1969/plymouth/roadrunner/parts/mb321.html

The Belvedere tach installed in the 69 cluster is pictured below bit blurry of a pic but…

Mine works like yours, Richard.

Mine works I believe remarkably well for a stock '69 tach? I wouldn't use it to fine tune a performance build? But idles around 1000 rpm. And on a lonely HWY stretch pushed to 6000 RPM while 150 speedo saying buried. (Phone's GPS captured more like 140 MPH.) Doing the math with 3.54:1 rear gear on 28" tall tire? Close enough. What was more remarkable? How stable a ride a 50+ year old GTX was at that speed? My fear was tire performance. The car was saying. "Is that all you got?" The car, engine and tach saying "I still have a couple hundred more R's left whimp!" On a mild hydrologic cam 440 build with an old orange electronic ignition module. Sometimes the stars just line up?

Comparing to my first '69 GTX of years ago? VERY similar build and 4-speed/rear gear Dana? This guy is not quite as quick thru the gears. But certainly better HWY commando. First GTX would have a very noticeable vibration at 130 MPH. The difference? First GTX had shorter/wider rear tires on 14" rim. This guy has 14" Rally rim fronts. Matching 15" Rally rim rears. Thus sporting a 2" taller tire. Because the rear of car sits about an 1 1/2" higher? I believe stabilizes car better at higher speeds? I have no real science to confirm. Just observation. (Of course output from clutch thru driveshaft could also be better balanced? But again, no real drivetrain dyno data to confirm.)

I guess my point is? That with first GTX. Because it was less stable? Both speedo and tach bounced around more. I noticed nether settle down quick enough to be any where near accuracy of today's electronics.