Tachometer innacurately LOW at high rpms
Thread Starter
Junior Member
Joined: Apr 2013
Posts: 40
Likes: 0
From: Huntington, NY
Car: 1989 Camaro IROC-Z
Engine: 305 TPI
Transmission: T5
Tachometer innacurately LOW at high rpms
So i just installed my tach, it idles correctly, but it seems like hearing by SOUND the redline is about 3k rpm according to the tach... im afraid to go higher because im afraid to blow the engine. It just doesnt sound right... im pretty sure it is actually redlining jbut not according to this gauge, im afraid to bring it any higher than 3k... i feel like the needle is moving less than it should be.
I hear alot of people have tachs that read HIGH, but it seems like im the first with this issue of it reading low!!!
i still have my old v6 tach, could i swap out the tach motor and put it into the v8 tach? or will that not read properly too?
I hear alot of people have tachs that read HIGH, but it seems like im the first with this issue of it reading low!!!
i still have my old v6 tach, could i swap out the tach motor and put it into the v8 tach? or will that not read properly too?
Supreme Member
Joined: Oct 2004
Posts: 4,528
Likes: 240
From: Henrietta NY
Car: 1984 Trans Am L69
Engine: Sniper EFI Powered 355
Transmission: WC T5 w/ Steel Support Plate
Axle/Gears: 3.42 10 Bolt Posi
Re: Tachometer innacurately LOW at high rpms
Pull the tach and check the resistor network.
Supreme Member
Joined: Jan 2006
Posts: 3,341
Likes: 10
From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
A Tach Plan
Originally Posted by jimmyd
what should they be reading?
It’s contained on a small plug-in PCB or integrated in the main board.
On or near the PCB you’ll see a capacitor, replace it.
Also 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!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
I’m Going To Win All My Races In 2014 . . . . . . . . . Or Not
Thread
Thread Starter
Forum
Replies
Last Post
ambainb
Camaros for Sale
11
Apr 25, 2016 09:21 PM