FAST Tach signal exist?

[Eticket]

Hello,

Is there a wire on the old fast box that can be used as a tach signal? I've been using the factory wiring with no long term luck... too much to explain. Just wondering if there is, in fact a wire to be used for a tach signal.

Thanks,
John Nguyen

New best 6.51@107 short shifting (because of problem above)

 

[Otto J]

You can probably use pin X3 coming out of the box.
That is the points output wire.Some older boxes it is not enabled though

 

[Eticket]

Is a points output wire the same as a tach signal? or will I have to do anything with it?

Is a "speedpro" box probably too old?

Thanks,
John

 

[Louie L.]

John,
What kind of problems has the stock tach wire been givin ya? Should work just fine even with an old box.

 

[Eticket]

As I understand it, the tach lead on the driver's side valve cover is looped around with the tach lead in the dash. I've conceded in my head that one of the two wires must be slighted grounded or something.

Basically, it works ok with a racepak dash and trans controller hooked up, except for when I "punch" the throttle. The tach signal goes away as I won't see rpm on the dash. I have no idea what happens at WOT because I never look down then (auto trans).

In old data logs, the trans was shifting at the correct RPM, so I assumed that it was getting the proper signal. (whether or not the dash was reading)

What happened yesterday was that I reinstalled a new caspers VDO tach adapter. That had solved the tach signal going away, before, for approx 75miles of driving before it died... the new one yesterday died during my 1st 1/8th mile pass.

 

[Louie L.]

You could pull the signal out of the coil pack connector? Do you have an after market ignition module ? Ive seen some loose or not put out a tach sig out at all.

 

[Louie L.]

You could pull the signal out of the coil pack connector. Do you have an after market ignition module ? Ive seen some loose or not put out a tach sig out at all.

 

[Eticket]

Thanks Louie. I have a new GM Module, but it looks just like the aftermarket piece.

The issue I'm having is that the racepak dash doesn't read RPM when I "stab" the throttle quickly. Doesn't come back until I'm off of the throttle and fine otherwise. I figure the lead is just too weak to feed the dash and trans controller.

It's fine for racing now, but I will eventually want to get this issue fixed.

John