v8 tach in a V6?
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Supreme Member
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Joined: Jan 2009
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From: Mesquite, Texas
Car: 89 rs, 86 Trans Am
Engine: RS-V6... Trans Am-LG4
Transmission: RS-T5... Trans Am 700r4
v8 tach in a V6?
I already have tried three different V6 tachs in my car, and they were all worng (reading too high) The one I have now is the closest, and it reads 4000 RPM on the highway.
I have a low mileage V8 tach over here that I would trade to anybody that has another V6 tach for me to try, but in the meantime I'm thinking about just putting it in my car
if I undertand the math, the v8 tach will read 33% lower than normal, which means that if the tach is perfect, I will be idleing around 600 RPM, and running about 1800 on the highway.
If it's getting old and is high, then at least it should be closer than the V6 tach... right?
BTW, if I put it in the car and it works perfectly, I could always sell it as a fully functional V8 tach, which might bring a nice price, and I can always put my V6 tach back in if I don't find another one
I know the oil pressure guage won't be right, and other downsides to this that I'm missing?
I have a low mileage V8 tach over here that I would trade to anybody that has another V6 tach for me to try, but in the meantime I'm thinking about just putting it in my car
if I undertand the math, the v8 tach will read 33% lower than normal, which means that if the tach is perfect, I will be idleing around 600 RPM, and running about 1800 on the highway.
If it's getting old and is high, then at least it should be closer than the V6 tach... right?
BTW, if I put it in the car and it works perfectly, I could always sell it as a fully functional V8 tach, which might bring a nice price, and I can always put my V6 tach back in if I don't find another one
I know the oil pressure guage won't be right, and other downsides to this that I'm missing?
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Joined: Jan 2006
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From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
Tach Flack
If the “V8 tach” you have is OEM you can calibrate it for the V6 by replacing a resistor in the dash.
It’s contained on a small plug-in PCB or integrated in the main board.
On the PCB you’ll see a resistor chip.
Desolder pins 4 & 10.
Use a 500K potentiometer.
Solder it across traces 4 & 10.
Move the potentiometer to half way.
Start the engine and compare the tach reading with a test equipment quality tach.
Dial it in, unsolder the potentiometer, measure it and install a matching resistor.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
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How bout those too scared to drive without headlights in the daytime
and the ones that need headlights for a little rain
.
It’s contained on a small plug-in PCB or integrated in the main board.
On the PCB you’ll see a resistor chip.
Desolder pins 4 & 10.
Use a 500K potentiometer.
Solder it across traces 4 & 10.
Move the potentiometer to half way.
Start the engine and compare the tach reading with a test equipment quality tach.
Dial it in, unsolder the potentiometer, measure it and install a matching resistor.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
How bout those too scared to drive without headlights in the daytime
and the ones that need headlights for a little rain.
Thread Starter
Supreme Member
iTrader: (3)
Joined: Jan 2009
Posts: 4,009
Likes: 6
From: Mesquite, Texas
Car: 89 rs, 86 Trans Am
Engine: RS-V6... Trans Am-LG4
Transmission: RS-T5... Trans Am 700r4
Re: v8 tach in a V6?
I thought that fix only applied to the 91 and 92 tachs....
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