Hooking up a Tachometer w/ Mark Ten Capacitive Discharge Ignition

[tomking]

I purchased a tach from Gene S and got it installed today. But I am not sure it is working properly. I have a Mark Ten Capacitive Discharge Ignition on this Manta and fired by what appears to be an early Crane breakerless system. There are 4 terminals on the coil which I am guessing were part of the Crane system. Where one would normally connect the tach, the negative side of the coil, that will not drive either the tach I installed in place of the clock, nor will it drive the tach/dwell meter I have. My tach/dwell meter must be connect to the far left terminal shown in the picture. However the panel tach must be connected to the BAT terminal on the coil to be driven. None of the other connections will drive it. Nor will any of the other connections drive the tach/dwell meter but the far left one. The PO installed the system and also installed cruise control, delay wipers, stereo system. All this is probably 20 years old or more. Does anyone know about these Mark Ten CD systems? And I dont know what this small box is between the crane box and the coil. It has three connections one of which is Bat + off the starter. The other two? I dont know. It only has Delco Remy on it and the number 841. One connection on it seems to be feeding some of these add on systems.

[BQS4]

Tom;
Just taking a shot it the dark here, as the Wagon I have had an Allison breakerless ignition, and a MSD spark enhancer. The MSD unit made the plugs fire twice, thus another MSD unit had to be used to help the tach read only one of the two pulses. This may be you case here, but, if you really don't need all that stuff on your car, why not pull it all off, and install a simple Pertronix and a stock coil, hook up the dash tach per the FSM and be done with it?
JMTCW

BTW, if the tach proves to be bad, I'll get you a replacement.

[guyopel]

Tom I have the Micronta CD sys. and for the Opel VDO tach it says that the tach lead goes to + coil terminal where the white wire is connected . If the reading is high or erratic add a 47k ohm 1/2 watt resistor and work down towards10k ohms between the signal lead and the coil until proper operation is attained .I started with a 47k ohm resistor and it worked correct for 15 + years . I went to radio shack (" Frys" also has these ) and bought mine .
Be careful with this unit with key on it can fire the coil and it will light you up ..not in a good way
In the back of my manual the CD unit I have is called a Mark 10 and looks the same as your unit.HTH
John L.

[markandson]

I actually have two new Mark 10 units, one of which I was going to put on one of my engines. They are simple CD ignition systems. One wire is power, one goes to the plus side of the coil, one to the negative side, and a fourth to the points or what ever else is being used in the dizzy. It basically is just an inverter that charges a capacitor which then discharges through the coil. The "points" are no longer switching high current, but become a simple low voltage on off switch which is used to fire the high voltage through the coil. HTH

[guyopel]

Yes , These work great and with the lower voltage across the points the points last a long time . You will need to regap your sparkplugs ..35 to 40 ths. works . Use caution in spinning the eng. over even with the dist. cap off it can jump from the center coil terminal to one of the sparkplug terminals in the cap You will use the stock or a" blue " coil but nothing "hotter" . HTH
John L.

[tomking]

Thanks GuyOpel. Then I guess thru sheer luck I have the tach hooked up correctly. But that same hookup will not work for the handtach dwell meter combo. Gene instead of cleaning this up I think I want to leave all this 70's 80's era stuff just as the PO had it down to and including the third brake light he installed in the rear package tray and the DeColores sticker on the bumper. This Manta was the guys pride and joy and I think I will leave it like he had it. Well except for the tach that is! Thanks for the tach Gene.

[tomking]

OBTW GuyOpel or Jeff, can either of you send me a copy of whatever documentation you have for the Mark Ten CD system? Thanks.

[tomking]

OBTW GuyOpel or Jeff, can either of you send me a copy of whatever documentation you have for the Mark Ten CD system? Thanks.
__________________
Do you know what the metal box is between the crane box and the coil? It has one positive lead going into the back, it has several leads that appear to be powering some of the PO's additions, and I dont recall what the third terminal is connected to. It is marked only Declo Remy and number 841?? Thanks.

[gr_diver]

Edited:

I had posted an idea about the metal box thingy here, but then I realized it was not possible.

[hrcollinsjr]

IIRC the CD type ignitions don't get along very well with standard resistor type ignition wires. Could the unidentified metal box be some type of electronic filter so the radio will function without alot of static?

Harold

[tomking]

Harold I would guess it is a filter; either that or an additional regulator. I cant imagine what else it could be.

[tomking]

Guyopel, I put a 50K variable resistor in series with the tach lead and it had no effect on the reading over the whole range of resistance. All help would be appreciated. And good you copy and send me whatever paperwork you have for your system as I have nothing. Thanks.

[guyopel]

Tom that is not what I posted . I said to start with a 47k ohm 1/2 watt res. and you should work down to a 10k ohm res.between the signal lead and the coil until proper operation is attained.The VDO tachometer is listed as a Transistorized triggered tach.
I would not use a var. res. with this setup.
My Book is not scaning clear enough to post .. sorry .
One other problem may be the year model of the Tach. you are using ..can you find out and let me know as I have more info. if it's a 73..75 Opel Passive tachometer
HTH
John

[tomking]

Guyopel, I was using the varistor to find what resistance I needed. Upon determining that I would buy and install permanently the fixed resistor. It wont make any difference if it is variable or not, that isnt the problem. I bought the tach from Gene Smith of Snellville and I dont know the year it came from. Gene??

[BQS4]

Tom;
I don't know what year Opel it came out of, it was in with other gauges I have. This is why I was siad to pull all that stuff off, get back to the stock ignition with just a Pertronix and the tach should work fine.

[tomking]

thanks Gene. It is only off about 3 to 400 rpm high so if I cant get it right on I will live with it. I really dont want to remove what the PO did. I will drive it and display it as a "period" tuning thing.

[Bill Hoffmann]

Originally Posted by tomking And I dont know what this small box is between the crane box and the coil. It has three connections one of which is Bat + off the starter. The other two? I dont know. It only has Delco Remy on it and the number 841. One connection on it seems to be feeding some of these add on systems.

I can't follow the wiring from the photos, but the small box may simply be a relay for the fog lights or something that he's using as a common tie point for the 12V source going to various things.

Bill

[markandson]

I punched "Delco Remy 841" into google and it came up with a voltage regulator for a Harley Davidson, it has 3 wires coming out of it.

[markandson]

I finally got around to looking for the new units that I had. Turns out they are Tiger 581 units, but they are basically the same as the Mark 10. I am having the instructions scanned to pdf files and will post them when available. There is good information about hooking up tachs included.

[markandson]

PDF of Tiger Instructions.

[tomking]

Thanks Jeff. It makes sense that it is a relay as it appears several add ons are hooked to it. I searched delco remy 841 but didnt find anything. As Guyopel had said in one of his postings, to get my tach to read I had to attach to the battery+ terminal on the coil. No where else will work. I will probably live with it reading 400 rpm high for a while. Thanks for everyones help.