Large display tach to attach to dash?

[littleape]

I've been adjusting my timing and noticed just how far off my stock dash tach is. It basically reads 2x the value of my little tach that attaches to a spark wire. My little tach shows 750 while the boats tach shows 1400. I'm assuming the spark plug tach is accurate, I have it connected to #1 close to the plug and its set to "3P1R" meaning 3 sparks per revolution for my 4.3 V6.

Is there a tach, that's not priced ridiculously, that I could run from a spark plug all the way to the dash of my 19' bowrider? The cheapo ones wires are barely long enough to get out of the engine bay.


THanks

 

[Scott Danforth]

Make sure your dash tack is set for 6 cylinders.

I always verify the dash tach with a photo tach, and adjust accordingly

 

[achris]

.... I have it connected to #1 close to the plug and its set to "3P1R" meaning 3 sparks per revolution for my 4.3 V6....

Something not right here. A spark wire based tacho only needs to know if the engine is a 2 stroke (one revolution per spark) or a 4 stroke (2 revolutions per spark) to give the correct engine speed.

As for an accurate tacho, use the wire coming into the dash tacho, as that's coming directly from the ignition system and give a pulse every time the coil fires (and that one IS 3 pulses per revolution).. I would find a digital tacho kit and build it up. That'll be as accurate as you can get, and no need for a long wire from the engine. All the wiring you need is already up at the dash.

Chris.......
(I'll find you a kit and edit it back in here once I find it)

EDIT:
http://archive.siliconchip.com.au/cms/A_102835/article.html

 

[littleape]

Oh nice didn't realize I could simply use a wire from under the dash. Would this signal wire be splice-able to keep both the stock tach and aftermarket digital one?

 

[Bondo]

Would this signal wire be splice-able to keep both the stock tach and aftermarket digital one?

Ayuh,...... Just daisy-chain it off the stock tach's feed terminal,.....