how do i fix my tach so it reads the correct rpm now that there is a v8 in my car?

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86 and 87 fiero database www.geocities.com/cwandall/fiero.html

you could buy one alredy done by archie. or buy the partys from him to do it yourself, or find the correct resistor to do it yourself, i have an archie tach that i havent installed yet and it has a varriable resistor, so i guess its adjustable,
if you need a pic it isnt in the car yet, just holla... and ill take a pic 4-U

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Rich AIM: ONE FAST 2M8:98 Black GTP 2 Dr
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http://home.t-online.de/home/O_Scholz/tach.html

Tim

[This message has been edited by Mickey_Moose (edited 10-10-2004).]

quote Originally posted by Mickey_Moose: the value that you need to set the pot for is 210K ohms for a V8. Tim

I bought 2 packs of resistors from my local Radio Shack, (99 cents+tax
each pack)
# 271-1347 pkg of 5 100K-ohm resistor, 1/4 watt 5% tolerance
#271-1335 pkg of 5 10K-ohm resistor, 1/4 watt 5% tolerance
I put 2 100K and one 10K together and i had about 208K
If you do decide to go the resistor route, instead of the 5% tolerance ones,
get the 1% tolerance.

Ed

Edited to get the Radio Shack stock numbers right.

[This message has been edited by ED's85GT (edited 10-10-2004).]

If you go the resistor way and you have a pack of them, measure them all with a good meter and put them one together that will add up to the correct value. You might get lucky at even at 10% to find a set that will add up to the value needed exactly. Best to use a pot (variable resistor) and 'dial' in the value.

See next post to determine the value...

Tim

[This message has been edited by Mickey_Moose (edited 10-10-2004).]

You have to calibrate it for your own meter. You can't just say "210k", and that's that. I think I had to make mine ~180k. You just need to measure your original resistor (with the trace cut, so it doesn't measure the resistance of the circuit as well), and multiply by 0.75. I think my original resistor was 230k, x.75 = 173k, so I was pretty close. The 210k only works if your original was 280k.

btw - this works only for the v6 tach.

[This message has been edited by ryan.hess (edited 10-10-2004).]

I am doing rockcrawls speedo mod for the 4.9L caddy. I bought the required resistors, but I got them all in 1/2 watt. Will this make a difference?

quote Originally posted by collinwestphal: I am doing rockcrawls speedo mod for the 4.9L caddy. I bought the required resistors, but I got them all in 1/2 watt. Will this make a difference?

Not at all.