XR GT

I recently converted my 250 to a 351.

Standard Tacho does not seem accurate. It idles at 1200rpm and touches 6000rpm under full throttle. I didnt think a stock 351 would touch 6k!

Does anyone know if the Tacho needs to be modified?

Cheers

normell

On the back of the tacho there should be a switch, 6 - 8, switch from 6 to 8 and try that.

__________________
Every day above ground is a good day
http://groups.msn.com/picturesofyourcars/normsauiiifutura.msnw

XR GT

Is this 6 to 8 switch on the back of the dashboard???

Cheers matey

xbgs351

There may be a dash pot.

The switch or pot will be located on the tacho, not the back of the dashboard.

xdc351

XE's don't have a switch, you'll need to but a V8 dash or pay a dash rebuilder to modify your 6cyl one.

I found this the hard way, the dash rebuilder claims he does heaps of them

__________________
Just like a Tsunami.

XR GT

Thanks heaps. Ive got a V8 dashboard around somewhere.

xbgs351

Is the XE tacho the same as an xd? If it is there is a pot you can adjust.

TruBlu351

On the tacho in my XD dash there are 2 screws adjusting screws on the back and a trim pot on the side.

It aslo has a "VDO 8" sticker on the back. Are you sure you can use it on a 6 and vice versa? Definitely no 6-8 switch like most tachos. It obviously measures pulses per second and converts this to an RPM so the calibration screws may work for you. You'll just need a hand-held version connected under the bonnet to calibrate it - just guessing and worth a try.

6 cyl @ 1000rpm = 6 x 1000 pulses per min = 6000/min = 100/sec.

8 cyl @ 1000rpm = 8 x 1000 pulses per min = 8000/min = 133/sec

So your 6 cyl tach will over-read by 33% on a V8. ie: 1200 = 800rpm. 6000 = 4020rpm.

The calibration screws may wind it down for you. While you're there, there's also a calibration screw hole on top of the speedo that most people don't know about (covered by a sticker) - good for tyre/diff ratio changes. Gives you ~+/- 40km/h.

My old work ethic or push, pull, prod, turn ,twist until it does what you want.

__________________
XE Falcon
393 Tremec TKO 9"

xbgs351

[QUOTE=TruBlu351] Are you sure you can use it on a 6 and vice versa? , QUOTE]

Yes, my brother did it with his. If you have a v8 unit available, measure the resistance of the pots, and set the 6 cylinder tacho to the same values.

TruBlu351

Cool, easy fix then!

__________________
XE Falcon
393 Tremec TKO 9"