Edited by brett_32i, 02 May 2006 - 06:57 PM.
changing tacho from 4 to 6 cylinder
Started by
_brett_32i_
, May 02 2006 06:56 PM
9 replies to this topic
#1
_brett_32i_
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Posted 02 May 2006 - 06:56 PM
is it possible to change a 4 cyclinder tacho to read a 6?
#2
_WYLDLC 6_
_WYLDLC 6_
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Posted 02 May 2006 - 07:07 PM
what type of tacho. If it's an after market one it is quite simple if not I'm not sure.
#3
_tj81_
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Posted 02 May 2006 - 07:07 PM
if its on an SLR guage, there is a switch on the back, i know for 6 and 8, i cant remember if there is a 4 cyl option.....
#4
_devilsadvocate_
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Posted 02 May 2006 - 07:13 PM
Yes its possible, but dont know how to do it myself, and instrument repairer will do it......expect to pay $40-50. Quite a common job for UC tachos.
#5
rodomo
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Posted 02 May 2006 - 11:09 PM
The following is a quote from the old forum, I kept it as I didn't know which tacho was in my son's UC as it was originally a sunbird. Turns out it was a 6 so I have never used this information but I hope it helps.
"Well i can help you out with this one as i had the same troubles with mine
1st- do u have standard ignition or electronic??
IF STANDARD
Go to dicksmith or any electrical store
ask one of the assistance for a 100k POTENTIOMETER
then what u do is where ur tacho connects to the coil follow this back inside the car and cut that wire then strip the plastic back and solder the potentiometer onto 1 outer pin and the other wire onto the middle pin
now start the car ur tacho pin WILL bounce now u get ur motor revving to 1000rpm then with a screwdriver turn the potentiometer until it sits on the spot
IT MAY NOT SIT ABSOLUTLEY PERFECT BUT ITS ACCURATE"
"Well i can help you out with this one as i had the same troubles with mine
1st- do u have standard ignition or electronic??
IF STANDARD
Go to dicksmith or any electrical store
ask one of the assistance for a 100k POTENTIOMETER
then what u do is where ur tacho connects to the coil follow this back inside the car and cut that wire then strip the plastic back and solder the potentiometer onto 1 outer pin and the other wire onto the middle pin
now start the car ur tacho pin WILL bounce now u get ur motor revving to 1000rpm then with a screwdriver turn the potentiometer until it sits on the spot
IT MAY NOT SIT ABSOLUTLEY PERFECT BUT ITS ACCURATE"
Edited by rodomo, 02 May 2006 - 11:10 PM.
#6
_brett_32i_
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Posted 03 May 2006 - 09:44 PM
i was hoping it was as easy as fitting a resistor.
it sounds from his description, that by adjusting the pot, you minimise the 'bounce'.
so the needle will always be moving +/- the same value, and you just zone in to achieve as little bounce as possible???
it sounds from his description, that by adjusting the pot, you minimise the 'bounce'.
so the needle will always be moving +/- the same value, and you just zone in to achieve as little bounce as possible???
#7
rodomo
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Posted 04 May 2006 - 03:15 PM
I think you should be able to eliminate bounce. I think the post refers to initial start up before adjustment. Obviously you would have another tacho hooked up to synchronise to.
#8
_brett_32i_
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Posted 08 May 2006 - 07:30 PM
ok, what i have found over the net is...
get the 10k pot, multi turn for better accuracy.
solder it across the 2 terminals of the needle coil.
what it does is lower the voltage to the needle coil, and therefore you can wind the pot to match the new tacho to a known tacho.
i'm just knocking up a square wave generator, so i'll keep you posted....
get the 10k pot, multi turn for better accuracy.
solder it across the 2 terminals of the needle coil.
what it does is lower the voltage to the needle coil, and therefore you can wind the pot to match the new tacho to a known tacho.
i'm just knocking up a square wave generator, so i'll keep you posted....
#9
Heath
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Posted 08 May 2006 - 08:23 PM
For the reference:if its on an SLR guage, there is a switch on the back, i know for 6 and 8, i cant remember if there is a 4 cyl option.....
Yes, there is also a 4cyl option. But early SL/R Guages (With MPH listed also) there is no option at all; V8s only.
#10
_devilsadvocate_
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Posted 09 May 2006 - 11:08 AM
Brett, an easy option for calibrating is to use a battery charger.
It wont have a smoothed output, but should be fully rectified giving 100 12V pulses per second.
Connect the tacho in the normal way to the 12V car system, but use the +ve of the battery charger as the input rather than the -ve from the coil, connect the -ve of the battery charger to the body of the car.
100pulses per sec = 6000/min
If its a six there are 3 pulses per rev.
6000/3 = 2000rpm
hope i got that right!
It wont have a smoothed output, but should be fully rectified giving 100 12V pulses per second.
Connect the tacho in the normal way to the 12V car system, but use the +ve of the battery charger as the input rather than the -ve from the coil, connect the -ve of the battery charger to the body of the car.
100pulses per sec = 6000/min
If its a six there are 3 pulses per rev.
6000/3 = 2000rpm
hope i got that right!
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