DIY: Home-Made Rev Limiter For Carbs

[SCT]

I found this on another forum It works!

http://i23.photobucket.com/albums/b3...diamgram-1.jpg

Basically, a tachometer with a shift light is wired to a relay. That relay is also wire to the distributor. When the shift light turns on, it kicks the relay then the relay shuts off the distributor temporarily until the shift light goes off (when the RPM drops).

http://www.corollacarclub.com/forum/...ead.php?t=8239

[Flashmn]

You can fry your ignitor and coil with that. Just a heads up.

[Bitter]

but the concept is sound, have it cut power to the igniter and the coil won't fire rather than cutting power to the coil.

[freakinbox]

or you could just use the tach and when you get used to the motor listen to the sound of the motor to not over rev it.

[Donald]

Does the name Rube Goldberg ring a bell?

For those of you too young to know:

http://en.wikipedia.org/wiki/Rube_Goldberg

http://en.wikipedia.org/wiki/Rube_Goldberg_Machine

[Bitter]

Originally Posted by freakinbox

or you could just use the tach and when you get used to the motor listen to the sound of the motor to not over rev it.

unless you mis-shift or something happens. add in a clutch switch to this device and you can make a NLTS box more or less. cuts the ignition when you put the clutch down so you don't need to lift throttle to shift.

[REN69]

I thought 4AF's had rev limiters just like the 4AFE and 4AGE... no?

[Flashmn]

nope

[SCT]

Originally Posted by REN69

I thought 4AF's had rev limiters just like the 4AFE and 4AGE... no?

Yea it does, the driver side floor panel.

[canadianae92]

you can do the same thing without having a super gay tach and shift light by using a voltage triggered switch which would be like your shift light and a variable resistor that is controlled by a knob like on that rpm gauge

I got a set of weber dcoe 40s so i gotta think about ignition might do this if I DON'T get msd 6al, like if I find a 6a for a good deal or something. And maybe wire up two relays, one on a normally open switch that is only engaged when you engage it manually and returns after use(forgot the name of them, modular switch or something) for launching.

Also I don't see how your ignitor would be damaged when there is no current running through it

[Flashmn]

you can do the same thing without having a super gay tach and shift light by using a voltage triggered

I dont think that would work, as the voltage is constant 12 switched by the ground, its more like the frequency of the ground switching.

[canadianae92]

Originally Posted by Flashmn

I dont think that would work, as the voltage is constant 12 switched by the ground, its more like the frequency of the ground switching.

isn't our tach fed by a rising voltage level? I'm talking about using an adjustable resistor in front of the volt triggered switch so it would work the same as the huge tach with a shift light

if our tach isn't fed by rising voltage level what is it fed by?

anyways there is definitely a way around having to use that gay tach and shift light by using an adjustable resistor and some sort of triggered switch, the switch working the same only triggering when it sees a certain amount of current just like that light does

maybe you have to convert the signal or something, maybe that's what the tach does?

i don't have all the answers that's for sure

[Flashmn]

if our tach isn't fed by rising voltage level what is it fed by?

Tachs are never operated with a rising voltage signal, they're operated by grounding, thus they are plugged to the ground side of the coil, which is always a ground. Coil always operates at 12V, not a rising voltage level.

I'm not sure how the resistor pills work on tachos, I believe it somehow alters the signal wire from the tacho (which I assume is some sort of switchable ground wire) and when you add a resistor in between it, the frequency signal level of that wire would change.

On a toyota 4A-F, the signal for the tacho comes from the negative side of the coil with a IIRC, through the ignitor, which has a 1000ohm resistor or in between it. Thats how I got my corolla tacho to work with the external controller, I put a 1000ohm (IIRC) resistor inline with the wire going to the tach from the negative side of the coil. I assume that the dash wiring has some sort of voltage signal going to that particular pin in the ignitor, which is grounded when the ignitor grounds the coil. Thats how I'm guessing it works.

I only studied 6months to be an automotive electrical engineer, before I switched to product engineering, so I didnt have the signal classes.

[canadianae92]

I'm starting electrical monday, I'm probably going to kill myself.

I don't know about the 4af but I think for the 4age it isn't from the coil grounding, I don't know what the 4age's rpm signal is from other than the wheel inside the distributor sends the signal to the ecu. There must be a way to not have to use that huge gay tach though.

Just thinking about electrical is giving me a headache guess I have to study more.

[SCT]

^There's a forum for car part sales, you know.

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Electrical stuff is a pain in the ass. Of course, for me, I just play around with it. Worse that can happen is I blow a fuse. But then again, I blew 2 radar detectors for having my cig lighter plugs backward and thought it was a faulty detector.