sun super tach cp7901

[gick70]

Picked up a old new tach minus the directions,question, what is the brass slide for on back of it?? It has about 3/8 travel,its not the selector for 4,6,8 cyclinders. Any thoughts???????????

 

[70_Steve]

This help?
http://www.sunpro.com/publish/2007/09/27/pdf_english_16472.pdf

Came from here.
http://www.sunpro.com/user_manuals.php

 

[DirtDonk]

Funny, but that fuse block in the instructions looks hauntingly familiar.

Paul

 

[gick70]

nothing about the slide

 

[DirtDonk]

Seems to me it was a zero-set feature. Mine has it I'm pretty sure, but it's been in there since '77 or so too, so it's hard to remember.

Have you tried fiddling with it while you watch the needle? See if it moves the zero point slightly.
Then again, it could be a calibrating tensioner for setting the gauges relative accuracy. Get it to something like 2500 or 3000 rpm, while checking it against another (supposedly known-good) tach, and trying to get the readings the same.
Probably reading too much into it there I suppose. It's probably just a fuhnertin rod end for the gangly wrench.
Self adjusting Quisinart Flux Capacitor initial setting dial.

Paul

 

[DirtDonk]

Might have to find my old instructions. Those are probably just for the current model, which is likely not equipped with that lever. Newer tachs probably have a more sophisticated movement that no longer required whatever it was it used to do.

Paul

 

[Rustytruck]

The tachs that I have seen with a slider was to set the zero point.

 

[broncoman1972]

The tachs that I have seen with a slider was to set the zero point.

That's what is says on the back of mine.

Funny to find this thread. I have a sunpro super tach II that I was thinking about using on my build to replace the oversize 5" currently on the truck. Thing is, on mine a previous owner had replaced all of the wires coming from the pack of the tach. Now they're all yellow. No idea what each is. The terminals inside the back of the tach are labeled T, B, L and G. Can someone with one of these tell me what color wire goes to what terminal in the tach?

 

[Viperwolf1]

I would guess T=tach, B=batt, L=light and G=ground.

 

[broncoman1972]

I called Sunpro's tech support to ask about my dilemma and he couldn't answer. He stated the harness from the factory is soldered in the tach, but mine clearly has push on terminals. I will probably try Viper's idea. It makes sense and he's been dead on in the past.