Tic toc tach accuracy

Posted By: Edahlke

Tic toc tach accuracy - 01/31/15 11:48 PM

Hi all,

I just installed the tic toc Tach into my 68 charger 440. Install was pretty simple, just power and the negative output from the coil. I have the mopar performance electronic ignition installed as well.

With the engine idling, the tach reads 0. It does increase as I give it gas, however the reading is always low.

I was under the impression the tach would work fine with the mopar electronic ignition. Is this true? Are these tachs just not very accurate?

Posted By: Sinitro

Re: Tic toc tach accuracy - 01/31/15 11:54 PM

Are U running a stepup electronic ignition box?
If yes, the OE Mopar tach will not read accurately..

Just my $0.02...

Posted By: 6PakBee

Re: Tic toc tach accuracy - 02/01/15 01:35 AM

Quote:

Are U running a stepup electronic ignition box?
If yes, the OE Mopar tach will not read accurately..

Just my $0.02...

What is a electronic ignition? Mopar electronic? Pertronix? MSD? All of the above? ?????

Posted By: Sinitro

Re: Tic toc tach accuracy - 02/01/15 03:33 AM

Quote:

Quote:

Are U running a stepup electronic ignition box?
If yes, the OE Mopar tach will not read accurately..

Just my $0.02...

What is a electronic ignition? Mopar electronic? Pertronix? MSD? All of the above? ?????

All of the above...
Beyond a standard points system..

Just my $0.02..

Posted By: 1970A66

Re: Tic toc tach accuracy - 02/01/15 03:49 AM

The tach will work fine with Mopar electronic ignition. It does on my 70 Challenger. Those factory tach circuit boards are NOT accurate.

Also the tach needle is press fit on and should read zero with the ignition key off.

Your tach has 2 parts: 1)the meter movement and 2) the circuit board.

Either one could cause your problem.
This is the best option for new circuit boards: http://rt-eng.com/rte/index.php/Main_Page
There are 2 67-74 boards. The more expensive has an on-board calibrator ckt.

Is your needle on zero with the car shut off? If so then I think your board is most likely bad. They have capacitors that often fail. But it could be a dirty/sticking meter movement causing the needle to remain on zero until you rev it to get it un-stuck.

Posted By: 1970A66

Re: Tic toc tach accuracy - 02/01/15 03:55 AM

http://www.forbbodiesonly.com/moparforum/showthread.php?61170-Factory-Tach-with-Electronic-Ignition

Posted By: denfireguy

Re: Tic toc tach accuracy - 02/01/15 07:17 AM

Quote:

http://www.forbbodiesonly.com/moparforum/showthread.php?61170-Factory-Tach-with-Electronic-Ignition

There is some confusion in that thread and it stems from the different types of electronic ignitions.
Mopars ignition system using the black box, orange box, chrome box, etc. uses a reluctor to replace point signaling and a large transistor switch to ground the coil to start the spark sequence. As a result, the switching voltages are the same as the old points system so there is no difference in tach signals.
MSD, Mallory and others are what use to be called capacitive discharge systems. They use an inverter to generate around 400 volts to discharge through the coil with a charged capacitor and attaching a tach without the adaptor will destroy the factory tach. IF it did not destroy the tach, it would also be inaccurate as most of them employ multi-spark events on each plug firing at low speeds to insure fuel burn. The adaptor for the tach solves both of those issues.
Craig

Posted By: Sinitro

Re: Tic toc tach accuracy - 02/02/15 09:33 PM

Quote:

There is some confusion in that thread and it stems from the different types of electronic ignitions.
Mopars ignition system using the black box, orange box, chrome box, etc. uses a reluctor to replace point signaling and a large transistor switch to ground the coil to start the spark sequence. As a result, the switching voltages are the same as the old points system so there is no difference in tach signals.

Incorrect...
An OE Mopar tach (up to 71) will not read accurately with a Mopar electronic ignition, electronic distributor w/orange, chrome or gold box. The tach will indicate some RPM level but it is not accurate.

Regarding other aftermarket systems, Mallory, Pertronix, MSD U better check with the respective manufacturer about compatibility with the various tachs be it OE or aftermarket.. As some external dongle adapter may be required.

Just my $0.02..

Posted By: denfireguy

Re: Tic toc tach accuracy - 02/03/15 04:16 PM

My mistake not addressing accuracy. I was only talking about the proper voltages and damage to the tach itself.
Just to clarify, the voltages present with capacitive discharge systems are too high for factory tachometers to handle and will result in permanent damage. Conventional Mopar systems, points or electronic, will not damage the tach. It still may not read right as the wave forms are not what the tach expected. Dwell on points systems was usually much longer and adjustable. On electronic systems, while somewhat adjustable by adjusting reluctor gap, it is much shorter and presents a different duty cycle to the tach than it was expecting.
Craig

Posted By: DPelletier

Re: Tic toc tach accuracy - 02/03/15 05:31 PM

OK, for those of us running the Mopar electronic distributor and orange box, can you make the factory tach read accurately?

Dave

Posted By: Sinitro

Re: Tic toc tach accuracy - 02/03/15 09:03 PM

Quote:

OK, for those of us running the Mopar electronic distributor and orange box, can you make the factory tach read accurately?

Dave

No...
On my 70RR, I swapped out the Tic/Tac for a tach using the VDO insides from RedLine. RedLine custom makes a front plate using the same fonts as the OE Mopar so it matches the other guages. My ignition system is the Mopar electronic distributor and chrome box. I also have run an MSD box without issues except the tach is driven from the MSD box rather than the coil.

Just my $0.02...

Posted By: DPelletier

Re: Tic toc tach accuracy - 02/03/15 10:48 PM

Quote:

Quote:

OK, for those of us running the Mopar electronic distributor and orange box, can you make the factory tach read accurately?

Dave

No...
On my 70RR, I swapped out the Tic/Tac for a tach using the VDO insides from RedLine. RedLine custom makes a front plate using the same fonts as the OE Mopar so it matches the other guages. My ignition system is the Mopar electronic distributor and chrome box. I also have run an MSD box without issues except the tach is driven from the MSD box rather than the coil.

Just my $0.02...

Thanks but I already paid $425 for the tach from Charger Specialties (plus duty, shipping and exchange so probably really about $750.00).

I can't see ripping it apart and paying another $300 - $400 so I guess I'll just go by ear for now. ....maybe a hidden rev limiter for safety..

Dave

Posted By: Sinitro

Re: Tic toc tach accuracy - 02/04/15 12:04 AM

Quote:

Quote:

Quote:

OK, for those of us running the Mopar electronic distributor and orange box, can you make the factory tach read accurately?

Dave

No...
On my 70RR, I swapped out the Tic/Tac for a tach using the VDO insides from RedLine. RedLine custom makes a front plate using the same fonts as the OE Mopar so it matches the other guages. My ignition system is the Mopar electronic distributor and chrome box. I also have run an MSD box without issues except the tach is driven from the MSD box rather than the coil.

Just my $0.02...

Thanks but I already paid $425 for the tach from Charger Specialties (plus duty, shipping and exchange so probably really about $750.00). I can't see ripping it apart and paying another $300 - $400 so I guess I'll just go by ear for now. ....maybe a hidden rev limiter for safety..

Dave

Dave..
The tachs from Charger Specialties have later internal electronics in them, so they are compatible with the older point systems, Mopar electronic systems, MSD and most
aftermarket ignition systems.

Just my $0.02...

Posted By: DPelletier

Re: Tic toc tach accuracy - 02/04/15 01:40 AM

Quote:

Quote:

Quote:

Quote:

OK, for those of us running the Mopar electronic distributor and orange box, can you make the factory tach read accurately?

Dave

No...
On my 70RR, I swapped out the Tic/Tac for a tach using the VDO insides from RedLine. RedLine custom makes a front plate using the same fonts as the OE Mopar so it matches the other guages. My ignition system is the Mopar electronic distributor and chrome box. I also have run an MSD box without issues except the tach is driven from the MSD box rather than the coil.

Just my $0.02...

Thanks but I already paid $425 for the tach from Charger Specialties (plus duty, shipping and exchange so probably really about $750.00). I can't see ripping it apart and paying another $300 - $400 so I guess I'll just go by ear for now. ....maybe a hidden rev limiter for safety..

Dave

Dave..
The tachs from Charger Specialties have later internal electronics in them, so they are compatible with the older point systems, Mopar electronic systems, MSD and most
aftermarket ignition systems.

Just my $0.02...

Thanks, I was wondering about it's accuracy and I ASSuMEd that it was an accurate repop of the originals...I'll maybe check it with a friends spare from his racecar but sounds like I may be good to go!

Dave

Posted By: pattyboy 572

Re: Tic toc tach accuracy - 02/04/15 02:06 AM

This kit will convert any tic toc tach...I had a 1970 original, install a original mopar dist w/orange box accuracy was destroyed,this corrected it...easy to install...but if you purchased one of the newer repos this is not required..as mentioned http://premiumdashdecals.com/support/instructions_exact_reproduction_TB-OEM.pdf

Posted By: Pacnorthcuda

Re: Tic toc tach accuracy - 02/04/15 02:06 AM

i upgraded a factory Cuda ralley tach with the modern digital board only to find out that the factory movements from the period are very heavy (slow) compared to the aftermarket or modern techs we're used too.

They can be fine for reading steady state cruise rpms but upon fast acceleration they can be brutally slow, lagging behind the true RPM by hundreds. Not good for getting an idea on shift points.

I ended up mounting an aftermarket tach right in front of it.

Posted By: dangina

Re: Tic toc tach accuracy - 02/04/15 05:17 AM

Quote:

The tach will work fine with Mopar electronic ignition. It does on my 70 Challenger. Those factory tach circuit boards are NOT accurate.

Also the tach needle is press fit on and should read zero with the ignition key off.

Your tach has 2 parts: 1)the meter movement and 2) the circuit board.

Either one could cause your problem.
This is the best option for new circuit boards: http://rt-eng.com/rte/index.php/Main_Page
There are 2 67-74 boards. The more expensive has an on-board calibrator ckt.

Is your needle on zero with the car shut off? If so then I think your board is most likely bad. They have capacitors that often fail. But it could be a dirty/sticking meter movement causing the needle to remain on zero until you rev it to get it un-stuck.

this is awesome! I didn't even know about these guys! now I know where to buy the stuff when I have problems - props to you!

Posted By: DPelletier

Re: Tic toc tach accuracy - 06/02/15 11:44 PM

Well to update; my Charger Specialties tach is apparently NFG. they used some sort of composite/graphite body when I bought mine and there are grounding issues. I bought the tach probably 8 years ago but the car has less than 20 miles on it...didn't last long!

Sooooo, I can rip it out, take it apart and attempt to add proper ground wires.....or I can buy a new one somewhere and replace it......or I can give up and bolt a tach to the steering column like people used to do back in 1969.

Dave

Posted By: ahy

Re: Tic toc tach accuracy - 06/03/15 04:21 AM

I had my '70 Rally tach rebuilt and run it with MSD + the correct signal converter. It works in the sense it moves to the right as revs increase. Is it accurate? No +/- 300 RPM... mostly plus. I measure against the EFI computer that counts crank pulses and should be accurate.

Think I'll add a tach on the column...

Posted By: mopar346

Re: Tic toc tach accuracy - 06/03/15 04:51 AM

Not to hijack but............is there a fix for the tach in my AAR readign roughly double the RPMS. I'm running and undercap conversion from Accel, essentially a Unilite module. Been running it for 7k+ miles now, no damage just double.

Thanks in advance, Kevin