nhdungeonracer

How accurate would you guess the stock tach's are? I have a 93 LX, and according to my AutoMeter Light tach, there's over a 1000 rpm difference in the upper rpm's, with the lite tach reading higher. Last nite when I raced, I followed the stock gauge (setting the lite gauge higher to compensate for the difference), but the more I thnk about it, something keeps telling me I should be paying attention to the light tach over the stock tach. What do you guys think?

In case you're wondering, I was shifting at 4700-4800 rpm on the stock tach, which was about 6000 on the lite tach.

Milky

Is your car stock or what? Shifting in the 4s is a bit low and at 6 means youve got some mods.

TheGmKiller331

Nah it doesnt.6000 on a stock motor is about right.Anything after and the valves most likely will float.

The stock tach is off yes by how much i dont know but theyre repeatable and thats all that matters.If you have an aftermarket tach why the hell are you paying any attention to the stock one?Who cares what it says?

vfast

valve with float aroung 6400-6500 this is why the computer is set at 6250 for the rev limiter. there is no power to be gained above 6k even on a mild engine....this is why roller engine are great with the high quick ramps on the cam to quickly build hp in the lower range unlike with a flat tapped cam 6500 was the norm

88stang5.0

i wopuld def go with the autometer. i have a autometer monster tach and it does the same thing. the stock tach will be at like 6 and the autometer is at about 5200 or so it differs. def go with the autometer.

nhdungeonracer

Because I'm new to this stuff, remember? I've never drag raced cars before, and this car I bought the way it sets. I'm learning as I go, plain and simple. Yeah, I'm over 40, but never had a chance to race cars a whole lot. Did do some oval racing 20 years ago, and yes, I had a tach then. But I bought that tach, and I installed it. Therefore, I understood how it worked. This light tach is a whole new ball game for me (they sure weren't out 20 yrs ago), and I got no instructions with it. When I finally did, and understood how it worked, I wasn't sure it was accurate, so I picked the stock one. But something kept eating at me, so I asked here if it was the right decision. Seems while my decision wasn't exactly right, it worked out. Shifting according to the stock tach at around 4700 was around 6000 on the light tach, and that's what most here are saying is right. Guess I got lucky, cuz I know this could have backfired.
I know you don't need proof, but here's a pic anyway. You can barely see the light on, and the tach is at 6000. And in case you're wondering, no, the reaction time is not 6.74 seconds It's actually .674 on a .500 tree. That's just the way NED has it's system set up, with the decimal in the wrong place for R/T's.

Moosetang

My autometer phantom nearly blinds me when it goes off.

bmorrisj

same here on my light, i want to get the led light but i dont want to spend anymoney because mine works fine...

VertStangGT86

Well you're staying yours reads higher then stock 88stang is saying his reads lower the stock. That presents a problem for me. That means you don't know which one is right, if the stock ones always read low then that would be one thing. Also since there's the chance something with the install was wrong I'd probably go with the stock. That's what the car has been driven according to since it was new. Make sure it was all installed right and/or call the manufacturer and ask them to make sure it's all right then go according to the new one. Also does it read off at lower RPM's too? If it does there's something to start with too. Your voltmeter should be lower at at idle and go up around 1000-1200.

roundman

if it blinds you, put the yellow cover over it at night to dim it down some, that's what it's for!
NH, I just installed an Autometer monster tach with shift lite on my '88 and it didn't want to work correctly either. I e-mailed the factory and they told me to check and make sure the voltage supply to the tach was at least 12.5 volts at all times and to use a piece of coax cable for the sensing wire since mine wouldn't go up past 5,000 rpm before dropping back to zero and staying there. I did everything they said and it still wouldn't work right so I pulled it and sent it back to them this week to see if they can find out what's wrong with it. you could go to a shop with a stand alone tach and get them to hook it up and check both yours against the shop one and see which one reads closest to the shop one is what I recommend you try.