My engine uses the point and condenser ignition.
The SIX tach I had was for a car with the Bosch CDI box module. Not compatible. wrong idle speed and "floaty" needle after that.

the FOUR tach however is very responsive and constant, just 150% too high.

Question is this: besides paying $275 to have my tach refaced and recalibrated, is there a Radio Shack electronic componet that could be wired before the Tach to "calibrate" it? In affect tricking the tach into thinking I still have a FOUR?

Anbody got a pre '69 SIX tach that goes up to at least 8k RPM's?

I don't want to use a "Sun" or "Auto-Meter" guage.
VDO is what I want.

KT

QUOTE (trekkor @ Feb 4 2005, 10:00 AM)

the FOUR tach however is very responsive and constant, just 150% too high.

just play with different resistors until it goes down to 100% ...

Andy

PS: i'm not sure if this works btw., i don't know how the tach signal actually looks like when it get's to the gauge ... i can't imagine it to be a steady current ...

How about adding a CDS ignition to the engine?? Something you should do for racing anyway...

Cheaper than paying $275 for a recalibrated tach!!!!! (Ouch.)

Dude, don't get rid of the 911 tach you have. If it is for the 3 pin CD box, keep it. Now, go out and find a 3 pin CD box (used is fine) or spend $150 on one of the MSD 6A CD's.

You will spend $$ on another tach or an ignition upgrade. Spend it on the ign upgrade.

If you find a 3 pin CD box, let me know, I can send you the wirring diagram for it. Easy hook up. Keep the points, loose the condensor (points trigger the box).

Oh, I guess the coil would have to go as well. Trust me, it is a much better system. I might even have a 3 pin box if your interested. Coil too.

I am not certain about the particulars (it would take me a while to relearn the required info to change things), but the resistor will not work. The gauge reads a signal that is either a box wave or saw wave, etc. The /4 gauge is calibrated to read the pulses in clusters of 4, the /6 in 6/. If you could find out what electronic component is different in the tach you could easily change it and it could only cost $.50. I may have to do this later. It depends on how my MJLJ works.

Sorry that I couldn't bee more help, but you can search based on what I told you and maybe find something.

Hey Trekkor, I have a early 911 tach that goes to 8K. I will sell it to you for the price I paid, I will have to check how much that was. I will actually be up in that area this weekend picking up a glider chair for the wife.

-Britain


BTW: This is my 1000 post!!!

I'm going to sport the MSD. ( mods already, I know, Nathan )
Sooooo, which 911 tach will I want to use that requires no mods?

KT

QUOTE (jkeyzer @ Feb 4 2005, 10:11 AM)

How about adding a CDS ignition to the engine??  Something you should do for racing anyway...

that's what i told him. but trekkor is not very good at "listening" ...

Andy

QUOTE

trekkor is not very good at "listening" ...

WRONG! Brad must be with you. That's something he would say

Decision made after listening, in just the last hour

Hmmmph....

Any of the "big wire" 911 tachs will work. I use a 71.
I think Dan said this before.....but you weren't listening
They also work with an MDS6AL without an adaptor. The 6AL has a rev limiter. Summit Racin' for the best price.

Who are you talking to about recal. your tach? United Speedometer in Riverside did mine several years ago, but I don't remeber it bein near that much. I do know they can handle all VDO guages. ......Dad

Palo Alto Speedo...

Here's my 8k tach. I had it calibrated for my Electromotive crank fire ignition. I don't remember what North Hollywood Speedo charged me. I seem to remember a thread on the bird board, one member was an electrical engineer and gave a detailed discription of how he recalibrated his tach for next to nothing in parts. Might be worth a search.

You will have to do a little adjustment on some of the components. If you use a stock ignition then you don't need to change the input signal.

Tach Conversion