[Half-Inch Stud]

So I bought a 68 Rally Clock from a PY member. Installed it and realized i didnt test it. well i stripped a plastic gear while adjusting the time, and during the repair decided to change plans & RE-rebuild my Original 68 Tach.

So, Advanced Auto sells a BOSCH Tach that goes 0-8000 in 270* range like Stock. So i tore it down, and used it as guts on the 68 Faceplate. Takes two new drill-holes in the back cover to mount the Modern tach guts to the old sheetmetal cover. Front 68' Plate can match-drill into the Modern Tach plastic bar using #2 drill, tap and original screws.

(done this a decade before but THAT prior modern movementt locked-up because of CHINA..)

So, 68 Tach is all together nicely, and ready to go in the Dash. After the install goes well ( and it should) , then I would like to put a modern movement into the 68' Rally Clock for a future install. What clock movement fits?

[Greg Reid]

Don't know the answer on the clock movement but that's a great idea with the tach. Do you have any pictures? My tach hasn't worked in years possibly because of my HEI ignition.

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[Stuart]

It appears you can buy a quartz clock replacement: https://www.ebay.com/itm/153511803749 The ad says it's 100% USA made.

[padgett]

For a transistor (HEI) ignition you need a transistor tach, passive (single wire) won't work. Starting for the '72 model year, Pontiac tachs were transistor. Back in the day I converted hood tachs with the round ceramic circuit board to transistor by using a Vega circuit board and changing the trim capacitor to a 33 ufd (.033 mfd) for a V8 (47 for a 6 cyl, 68 for a 4)

[Scott Thelander]

as stated in the ad

"While the clock face looks identical to the original, "

yah ok ,,,, its kinda close for 69-72 but 68 nawt even close ....

maybe use your facia??

but I still like the click sound on rewinding ,,,,

I would have offered you a clock but my 68's all have rally gauge mates ...

S T

[Half-Inch Stud]

Scott, Nice Rally Gauge Stash!
Padget, The Bosch from Advanced Auto requires the +12V line. Seems to be accurate.
Greg, Photos would appear like Factory stock look. Nuthin to see. I might post a photo later.

Stuart, Thanks for the ebay link. my Clock works, but i stripped a red plastic gear tooth for setting time. me thinks a Quartx movement might or might not solve that problem.

Pro-trick tip: The new tachs can tend to Compass-up when off if the car is pointed such way. When powered the Tach goes CCW to ZERO, but if compassed-up at 5800 rpm or more then it will go to 8000 rpm when poweredup and be stoopid for that drive. So, i epoxied a toothpick section to the Rally Tach Centerbutton at 6000 for positive stop, and power-up will go to zero. My SD-rodded engine doesnt need to go past 5500 rpm.

[Stuart]

Another thought is to check through the gears at https://www.odometergears.com He makes all kinds of gears to fix odometers and speedometers, and is well known for his service and quality. I don't know if he has anything for clocks, but maybe there's something in his inventory that can be made to fit.

[Half-Inch Stud]

Stuart, Thanks, you motivated my search and found OPG for GM clock stuff...
https://www.opgi.com/gauges-accessor...t-s003015.html

[Verdoro 68]

I got my clock quartz conversion from Instrument Specialties years ago. https://www.clocksandgauges.com/quartz-conversion.html

[Ram Air IV Jack]

Originally Posted by padgett

For a transistor (HEI) ignition you need a transistor tach, passive (single wire) won't work. Starting for the '72 model year, Pontiac tachs were transistor. Back in the day I converted hood tachs with the round ceramic circuit board to transistor by using a Vega circuit board and changing the trim capacitor to a 33 ufd (.033 mfd) for a V8 (47 for a 6 cyl, 68 for a 4)

I'm wondering if you are Padgett Peterson, the tach guy?? If so, I've read a lot of your research on hood tachs for many years. I use your research to end many discussions on hood tachs and the mysterious 5500 vs 5100 redline debate. Sure learned alot about tachometers from Pagett Peterson!!!

[padgett]

Um errr ahh well, could be.

[Greg Reid]

Originally Posted by Half-Inch Stud

Greg, Photos would appear like Factory stock look. Nuthin to see. I might post a photo later.

No doubt..what l really should have asked is what Bosch Tach you used.


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[Ram Air IV Jack]

Originally Posted by padgett

Um errr ahh well, could be.

And of course I've been to your page on Zenith's TO radios. I picked up an H500 several years ago at a flea market. It didn't work BUT everything was there, manuals, accessories, etc. Case in very good shape too and at a very good price! Took it home, found the radio had been rewired to accept another audio output tube. Using the schematic and a correct tube, rewired it, bought a 1L6 tube, Zowie, converted the selenium rectifier to a diode set up and checking to make sure all filament voltages were within decent tolerances, it works great!!! Thank you again for your knowledge Mr. hood tach man!!!

[Half-Inch Stud]

RA IV jack; TransOcianic huh. 1L6 sounds hard to find. Diode swap in was a good move.
Greg, The only Tiny Bosch Tach Advanced Auto sells on-shelf : 0-8000 rpm and 270 degree swing like Stock.
Voodoo68; Thanks, I may call clocksANDgauges to see about the tiny gear(s) needed. Heck, maybe get their QTZ movement.

[6T9GTO]

HIS,

Did you use the factory tach faceplate with your setup? A pic of the installed tach would be great. Thanks!

[webfoot]

Pete Serio restored my non-operational tach and made it HEI compatible. He did a great job on the rest of the instrumentation as well.