| Author |
Message |
Terry Springer (Tspringer)
Junior Member
Username: Tspringer
Post Number: 204
Registered: 4-2002
| | Posted on Monday, August 12, 2002 - 8:57 am: | |
My car is carbs, no digiplexes that I know of. Ben has been helpful. On his car and the others his conversion has been installed in the tach worked fine connected directly to either the coil or the MSD. I have no idea why mine will not work like this.
I hope nothing is wrong with the tach. Well see when I get the adaptor. |
phil hooper (Wolftalk)
New member
Username: Wolftalk
Post Number: 30
Registered: 5-2002
| | Posted on Monday, August 12, 2002 - 2:55 am: | |
according to the electromotive documentation, most "modern" tachs operate off a 12V square wave (pulse stream). older tachs that tap off the coil require voltage spikes more on the order of 175V+. I don't have a scope, so I can't see what the digiplex puts out....it's not a 12V square wave, though.
the options - according to electromotive - replace the tach, have it rebuilt using different internals, or use a tach amplifier to boost the voltage to what the tach wants.
the electromotive kit from nick includes a tach amplifier, so it's pretty safe to assume you're going to need one if your digiplexes are removed. I suppose if you leave them in (or it, since only one may be used to read the engine speed off the flywheel sensor), the digiplex will drive the tach normally. |
magoo (Magoo)
Advanced Member
Username: Magoo
Post Number: 2976
Registered: 2-2001
| | Posted on Sunday, August 11, 2002 - 11:55 pm: | |
Terry, As Rich indicated Ben should have some idea as to what will correct the problem. How can you sell that unit and not be able to have tach function. I don't want to sound like I am beating up on Ben but I am sure he would want it to work correctly. Has he had similar problems on other Ferraris or is this a first? I feel that he should correct the problem. JMO |
Terry Springer (Tspringer)
Junior Member
Username: Tspringer
Post Number: 203
Registered: 4-2002
| | Posted on Sunday, August 11, 2002 - 9:20 pm: | |
I have tach function in my multimeter. I hooked this up to the negative terminal on the coil as per the instructions in the multimeter manual. Nada, no tach.
I then hooked the multimeter to the tach output on the MSD box. Voila! Tach working on the meter. This was good enough to help me with setting the timing and checking carb synch.
This also I think confirms the suspicions of needing the tach adaptor/amplifier. The MSD apparently does not provide enough pulse at the negative coil terminal to drive a standard tach. Im ordering the tach adaptor in the morning. |
Steve (Steve)
Junior Member
Username: Steve
Post Number: 185
Registered: 2-2001
| | Posted on Saturday, August 10, 2002 - 7:39 pm: | |
Tery do you have a tach/dwell meter? If so just hook it up normally and see if the tach works.I did a conversion to Pertronics breakerless ign. a year ago and hooked up the wiring with the brown tach wire on the coil neg. I have a 77 GTB also. |
Terry Springer (Tspringer)
Junior Member
Username: Tspringer
Post Number: 200
Registered: 4-2002
| | Posted on Saturday, August 10, 2002 - 7:11 pm: | |
Im going to call MSD on monday morning and have an adaptor overnighted to me. I hope that fixes it, because otherwise Im stumped.
It would sure seem that hooking it up just like it was before would make it work. The points are still in the old distributor. The factory wiring diagram has the tach wire attached to the negative coil terminal which is also wired to the points pickup on the side of the distributor where the condensor is mounted and wired. Just because the points are no longer determining spark does not mean they are not functioning. All of the original distributor internals are in place. I dont understand why it will not work when setup like stock? |
Bill Sebestyen (Bill308)
Member
Username: Bill308
Post Number: 306
Registered: 5-2001
| | Posted on Saturday, August 10, 2002 - 6:54 pm: | |
Some of the later electronic ignition systems don't provide a big enough signal for the early tachs. The MSD tach adapter is an amplifier. |
Edward Gault (Irfgt)
Intermediate Member
Username: Irfgt
Post Number: 1757
Registered: 2-2001
| | Posted on Saturday, August 10, 2002 - 4:59 pm: | |
You can drive the car without a tachometer until a solution is provided. My electromotive unit needed an adaptor. I think it was an amplifier. |
Terry Springer (Tspringer)
Junior Member
Username: Tspringer
Post Number: 199
Registered: 4-2002
| | Posted on Saturday, August 10, 2002 - 3:32 pm: | |
its a '77 308 GTB. The Millermon conversion is a single distributor and coil, im running it with the MSD6AL. It could be the tach adaptor is needed to make it run from the MSD tach output.
I would however think it could be made to run directly from the coil too? I can order the tach adaptor next week, but that yet another week off the road. My dang car has now been not running for a longer period that running since I have owned it. Not what I had in mind! |
Bill Sebestyen (Bill308)
Member
Username: Bill308
Post Number: 305
Registered: 5-2001
| | Posted on Saturday, August 10, 2002 - 3:16 pm: | |
It's very possible you do need the MSD tach adapter. I know it fixed the no tach operation when I installed my Electromotive system. I don't know if others required it for their Electromotive installations. What year is your car? |
Terry Springer (Tspringer)
Junior Member
Username: Tspringer
Post Number: 198
Registered: 4-2002
| | Posted on Saturday, August 10, 2002 - 2:34 pm: | |
Well, I connect the brown wire to the negative side coil and I get nothing. Tach worked before fine. Im pretty sure the brown wire is for the tach, but the wiring diagram is not a lot of help. Im basically pissed enough at it right now that im leaving it for the rest of the day. |
Edward Gault (Irfgt)
Intermediate Member
Username: Irfgt
Post Number: 1751
Registered: 2-2001
| | Posted on Saturday, August 10, 2002 - 1:53 pm: | |
Most all tachometers connect to the negative side of the coil. It has to have an interrupted voltage signal and that is where it is derrived on most cars. |
Terry Springer (Tspringer)
Junior Member
Username: Tspringer
Post Number: 197
Registered: 4-2002
| | Posted on Saturday, August 10, 2002 - 12:48 pm: | |
Anyone have any ideas on getting the tach to work? <punt> |
Terry Springer (Tspringer)
Junior Member
Username: Tspringer
Post Number: 196
Registered: 4-2002
| | Posted on Saturday, August 10, 2002 - 10:44 am: | |
So far, Ben has no answer either. I dont know if I need an MSD tach adaptor or if somehow the stock tach needs be connected to the ballast resistor. At this point, Im not even sure how the stock tach would be wired. Its a mess. The wiring diagram shows it going to the coil negative terminal but it does not tell if this is direct to the coil or on a ballast resistor. It then shows the wire going to the points terminal on the outside of the old tach.
Im pretty much at a loss. I obviously wont run a system without a tach, but it sure seems there would be a way to get MSD to work with the stock tach. |
Richelson (Richelson)
Member
Username: Richelson
Post Number: 804
Registered: 12-2001
| | Posted on Saturday, August 10, 2002 - 6:38 am: | |
I would contact Ben personally and see about it. I have the Crane XR700 units connected and if I remember correctly my tach wire went to the coil. They work with the stock tach. |
Terry Springer (Tspringer)
Junior Member
Username: Tspringer
Post Number: 192
Registered: 4-2002
| | Posted on Friday, August 09, 2002 - 9:06 pm: | |
I have been working on installing the Millermon distributor and MSD. I got it all hooked up and the car is running fine. Timing is set at (or close) 16' BTDC. (at least I think so, my flywheel has no marks here. It only has the marks for 7' BTDC, I counted over 3.5 more teeth and painted in a mark) The car is running ok, I have no actually driven it yet.
My problem is the tach does not work. I hooked the brown tach wire to the MSD tach output as per Bens instructions. Nada. Then I took it and connected it to the negative terminal on the coil with another lead running to the old distributor external points lead. I connected it to the same external post as the old condensor is still connected to. This did nothing, still no tach.
I occurs to me that perhaps since there is no current running through the old distributor now, their is no way for the action of the points to be picked up by the lead going to the coil? Millermons distributor bolts to the top of the old one in place of the old distributor cap. The old advance mechanism and points are still in place and operating, but are not actually participating in the ignition process any longer.
Anyone have any ideas why I have no tach? Tough to set the timing and evaluate advance with no tach. What should I try, im somewhat at a loss. |