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Inaccurate tik-toc-tach


FBBO Gold Member
FBBO Gold Member
Local time
12:20 PM
Aug 24, 2022
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Frankford, DE
Hi all,

In my continuing quest to address issues with the Super Bee, I see that my tic-toc-tach seems out of whack. I think it’s ok down low, but where the gear/tire calculator says I should be spinning about 2600 rpm at 60 mph, I’m at 3000 or a little over. Plus the needle tends to bounce around.

I’ve done a bit of research and want to pass this by you kind people.

Apparently a 1N4005 diode inline on the wire between coil negative and the tack will settle the tach down. Does the below look/sound right? Does anyone have a picture or two that shows this implemented?

Thanks again as always for your help!



Interested in seeing the responses. My tach needle does little fluctuations also.
Do you have electronic ignition ?? If so, your tach needs a conversion to properly read accurately.
I have MSD ignition. What kind of conversion are we talking here?
MSD Ignitions need a tach adaptor to run correctly - Part number #8920

You can rotate the tach body inside the housing to get zero RPM....

Is your speedometer correct ???? You may also need to change the speedometer pinion gear if the rev range is out on all gears.

Another question - is this an original Tic-Toc-Tac......or a later model Reproduction unit?
Has anyone ever actually thought their 1970 vintage factory tach is accurate??? :lol:
I measured mine against another good tach, and it was pretty darn closeup to 5,000 RPM....then the needle got a little ambitious after that.
My Tic-Toc-Tac had been worked on at a Specialist Shop many years ago for the clock, and they also checked the Tach part.
I put one of these in my 69 tic-top-tach, and set the calibration against a bench tachometer.

RTE 67-74 Tach kit - rte
ABSOLUTELY....i installed the RTE tach board in my origional MOPAR TIC-TOCK-TACH in my RS23V0A****** GTX and it operates more accurately than the original.....but...I have a Prestolite dual point distributor with points....no electronic anything.....
Even with the correct MSD tach adapter the factory tach in my GTX wasn’t very accurate. I swapped it for a reproduction from Redline Gauge Works that uses VDO internals, problem solved…