Help Delta Mark Ten CD Tach hookup SWB

[Allen Henderson]

Capacitive guys,

I had to repair my ignition system and now have lost track of where my Tach wire attaches to one of the 4 wires on the subject vintage CD hook-up. I thought it would be the wire directly to the points but the Tach is not working with this hooked up. I've had my Tach tested and it is OK.

I don't want to blow it up (thought I had!) Where does the wire attach? The Tach was working perfectly before I rebuilt my Distributor and the car is running perfectly with the CD. I just need to hook up the tach wire in the engine compartment to the right spot. Thanks.

-Allen-

[tomkirkcis]

If your tach is from a swb, (unmodified circuit board) it will not work with the Delta unless you have the Bosch inducer. Since yours was working can I assume you do have the inducer? If so, my car would be wired the same way as yours and I should be able to help you. I am traveling on business but should be able to look at my wiring on Friday. tom

[Allen Henderson]

If your tach is from a swb, (unmodified circuit board) it will not work with the Delta unless you have the Bosch inducer. Since yours was working can I assume you do have the inducer? If so, my car would be wired the same way as yours and I should be able to help you. I am traveling on business but should be able to look at my wiring on Friday. tom

Hi Tom,

Yes, it was definitely working. However, I am not aware of any reducer or any modification (unless it is in the tach wire/line somewhere)

On researching, I read from another board that the tach wire should be hooked up to the + coil input. I'm a little afraid to try it though as the thread was a little unclear.

-Allen-

[tomkirkcis]

The inducer is a small cylinder can with two wires. They were the factories solution to get old design tachs to work on the first cars fitted with cd ignition. They create the correct voltage square ware pulse that drives the early tachs. They redesigned the later tachs to work with the inherient signal available from a cd equiped iginition. I went without a tach for several years until I was able to buy an inducer from Fritter. The early tach can have its guts modified to work straight of the signal from the cd. How long have you had the car? Was your tach modified? There are threads on pelican that have pictures of the tach inducers. They may help you determine if you have one. If you post an image of your electrical panel in your engine compartment I could tell you if you have one.

[Allen Henderson]

I have no idea if my tach was modified but I doubt it; could have been of course. Palo Alto Speedo put it on the bench and it worked, that's all I know.

Again, it worked just fine until I couldn't get my car started in a parking lot ((ended up getting it towed and then replaced points and condenser at home(that was mostly probably then non-staring problem)) and, working on it in parking lot, lost track of the wiring.

-Allen-

[72tii]

The inducer is a small cylinder can with two wires. They were the factories solution to get old design tachs to work on the first cars fitted with cd ignition. They create the correct voltage square ware pulse that drives the early tachs. They redesigned the later tachs to work with the inherient signal available from a cd equiped iginition. I went without a tach for several years until I was able to buy an inducer from Fritter. The early tach can have its guts modified to work straight of the signal from the cd. How long have you had the car? Was your tach modified? There are threads on pelican that have pictures of the tach inducers. They may help you determine if you have one. If you post an image of your electrical panel in your engine compartment I could tell you if you have one.

I think Tom is right about this one. I had to install the inducer to get the tachometer to work in my '68 when I installed the Bosch CDI. The inducers actually have three wires.

Go to this thread on Pelican for more information with photos and wiring schematics.

Let us know how it turns out.

[edmayo]

I think I may have an old Mk.10 instruction book in my tool box. I 'll try to remember to look at it tomorrow and see if the tach lead is shown.

[Allen Henderson]

I think I may have an old Mk.10 instruction book in my tool box. I 'll try to remember to look at it tomorrow and see if the tach lead is shown.

Hi Ed,

That would be great. I looked at the earlier posts, including the link to an other make CD unit referenced above. I tried my Tach with the black/purple Tach wire hooked to the points and that didn't work..and now I know my Tach is good. The Pelican post shows a divider network to reduce the voltage to the Tach and has the Tach wire hooked up to the points which, again, doesn't work for my Mark Ten set up. So, I think different CD units work in different manners. Also, I tried this point hook up with two other Tachs, and it didn't work with either tach. I thought I had bad Tachs but now since my Tach test good, I'm pretty sure it is a hook up problem.

I just went out and checked my Tach wire again. Each end, in the engine compartment and under the front bonnet, comes directly out of the loom. So, if the Delta Mark 10 requires additional resistor or whatever in the circuit, it would have to be in the Tach.

I am leaning strongly toward the + on the coil hook up but, again, don't want to blow up my Tach. Thanks.

-Allen-

[911pcars]

Capacitive guys,

I had to repair my ignition system and now have lost track of where my Tach wire attaches to one of the 4 wires on the subject vintage CD hook-up. I thought it would be the wire directly to the points but the Tach is not working with this hooked up. I've had my Tach tested and it is OK.

I don't want to blow it up (thought I had!) Where does the wire attach? The Tach was working perfectly before I rebuilt my Distributor and the car is running perfectly with the CD. I just need to hook up the tach wire in the engine compartment to the right spot. Thanks.

-Allen-

I had a Delta Mk. 10 connected to my '69T for years. I don't remember any special electronics for the tach to work. I forget the connections, but as a guess (Mayo will hopefully provide the correct answer), I'd connect to the terminal going to the points. Second choice is to the direct - terminal on the coil. Both of these are usually reduced voltage signal circuits.

Connections to the + side of the coil will produce either a constant 12 volt signal (outboard connection) or a boosted voltage source to increase primary coil voltage (direct to coil).

In fact, I still have mine somewhere in storage.

Sherwood

[Neil '67 911S]

I've scanned the manual for a Delta Mark 10b, which has the switch between points/condenser and CD in the event of failure of the latter. I believe the wiring would be the same:

12 volt ignition coil wire => Delta red wire
coil + (terminal 15) => Delta white wire
coil - (terminal 1) => Delta black wire
distributor points wire => Delta green wire

Send me a PM with your email address and a request for the manual and I'll send it along. 500 K MS-WORD file.

I have a period-correct Red Ball CD unit (had one in Ol' Ivory) that I'll take offers for. It probably needs a rebuild.