pl2000n

I'm definitely interested in learning more about such a conversion. Is there a good thread to read? Thanks!

mrvette

I think the tachs would be from 75,76,77 vettes, when HEI came out they swapped to the electronic tachs....

As for overall accuracy, I took a digital audio oscillator and a Techtronics scope to the car once, trying to find out about the accuracy.....

and I found the electronic tach read some 600 rpm high around 4k rpm or so.....

and part of it was getting fried on that silly tire speed/rpm thing on some tire company web sites.....they are RONG!!!!
the speedometer tends to be optimistic in the readings they honest on my '72 until 80 mph which is really only 78 via GPS.....at 100 indicated mph, it was really 94 mph.....ran outta room, so test over....

methinks the tachs are set that way deliberately, same with speedos.....

Alex66

I know this thread is a few months old, but here is my experience with my 71' cable driven tach...


At idle and low rpm it is pretty acurate (at idle about 80rpm of), but at high rpm it gets really wrong readings... My rev limiter of my pertronix 3 is set at 6300rpm and should be +/- 50 rpm acurate. When I was acelerating quick in the low gears and the rev limiter kicked in at 6250/6300 my cable driven tach showed 5700rpm! (not that I constantly rev my engine that high, but I wanted to test it)

C3 Stroker

That's how my '69 cable driven tach is also......seems like a normal thing. I installed an Auto Meter elect. tach which I use for true accuracy for shift points. The cable tach suffers from bounce around 6k and looses accuracy fast. Mine only says 6200 at a true 7000 rpm.