csx4788 - msd - tach not working

shelby racer · #1 (**permalink**) 10-27-2007, 06:14 PM

Yeah, its me again. I finally got my beast fired up and it sounds great

! I still am sorting lots of thing out, but my latest problem is that I decided to run an msd 6 box, wired the green wire that was supposed to go to the coil originally to the tach out put on the msd box and the tach is doing nothing. I have checked the instruction and the schematics and searched the forums and it seems to be wired correctly, but is it? Any one else have this problem or is running a similar set up and it works? Thanks.
John(;-)

Full Throttle Al · #2 (**permalink**) 10-27-2007, 07:47 PM

If it is a Smith's tach, and I assume it is, you have to send it to Nisonger for modification to work with MSD box. Works fine thereafter.

Alan Sorkey
CSX4083, with MSD 6AL ignition.

PS I grew up in Santa Cruz and saw my first Cobra there, a 289.

kris-kincaid · #3 (**permalink**) 10-28-2007, 07:45 AM

John,

You need to make up a new wire going from the male spade tach output on the MSD box directly to the tachometer. The green wire should be dead and not connected to the coil or the tach or the MSD box.

This is totally optional, but I usually hook up the black wire on the MSD box that normally is connected to the coil to the green wire running from the tach to the coil. This eliminates running extra wires through the firewall.

This should work, if not we'll try something else.

Full Throttle Al · #4 (**permalink**) 10-28-2007, 08:30 AM

Check out the picture bottom right at this link:

http://nisonger.com/other-services.htm

Power Surge · #5 (**permalink**) 10-28-2007, 08:43 AM

Quote:

Originally Posted by kris-kincaid

John,

You need to make up a new wire going from the male spade tach output on the MSD box directly to the tachometer. The green wire should be dead and not connected to the coil or the tach or the MSD box.

This is totally optional, but I usually hook up the black wire on the MSD box that normally is connected to the coil to the green wire running from the tach to the coil. This eliminates running extra wires through the firewall.

This should work, if not we'll try something else.

Kris, you say "directly to the tachometer" but then you say not to use the green wire? Which wire does the tach input get attached too?

I am following this closely, as I have had some odd tach issues with my Vegas CSX with the SAI gauges. I have a VERY hard time getting a tach signal on the dyno. My garage door opener also won't work if my car is running, I have to shut it off. I'm pretty sure my tach is connected using the green wire.

kris-kincaid · #6 (**permalink**) 10-28-2007, 08:59 AM

The green wire is there for an original points style ignition. The green wire runs from the (-) terminal on the coil to the input on the tach. I believe it is wire #54 on the old style harness under the dash.

The MSD box sends the tach signal rather than the tach getting a signal from the coil like an original Cobra. So, you have to make up a new wire from the MSD box to the coil, and all is well.

shelby racer · #7 (**permalink**) 10-28-2007, 09:47 PM

Quote:

Originally Posted by kris-kincaid

John,

You need to make up a new wire going from the male spade tach output on the MSD box directly to the tachometer. The green wire should be dead and not connected to the coil or the tach or the MSD box.

This is totally optional, but I usually hook up the black wire on the MSD box that normally is connected to the coil to the green wire running from the tach to the coil. This eliminates running extra wires through the firewall.

This should work, if not we'll try something else.

Thanks again Kris,
A nor cal saac member offered to sell me his tach adaptor, but he also mentioned that wiring his tach to the coil made his tach work, so I was hoping that piggy backing the green wire to the coil (negative lead / black msd wire I think you said) should also do the trick. Am I correct? I would be very happy if I were. Then I can get back to replumbing the fuel system. I still think I am gonna run both - 6 lines from the fuel cell through a fuel block to the fuel pumps in the trunk and then just run a -8 line up to the engine compartment with a regulator and fuel filter that I already have up there. Let me know what you think on any of this.
John(;-)

rdorman · #8 (**permalink**) 10-29-2007, 07:27 AM

Like was said before... there is a male spade connector inset on the side of the box, that is where the tach plugs into. If it does not work, they you will need the tach adaptor.

shelby racer · #9 (**permalink**) 10-29-2007, 08:20 AM

Quote:

Originally Posted by rdorman

Like was said before... there is a male spade connector inset on the side of the box, that is where the tach plugs into. If it does not work, they you will need the tach adaptor.

Okay - originally had the spade connector directly connected to the msd, but kris is suggesting another way that he knows works - without a tach adaptor but that I am not really clear on (as are others apparently). Just kind of confused.

Power Surge · #10 (**permalink**) 10-29-2007, 08:25 AM

Quote:

Originally Posted by shelby racer

Okay - originally had the spade connector directly connected to the msd, but kris is suggesting another way that he knows works - without a tach adaptor but that I am not really clear on (as are others apparently). Just kind of confused.

I think what Kris is saying, is that instead of running the green wire on the tach to the tach output on the MSD, run it to the wire that goes from the MSD to the negative side of the coil.

shelby racer · #11 (**permalink**) 10-29-2007, 08:37 AM

Thanks Sal,
I though that that was what he meant, so I will try and piggy back the green wire to the negative side of the coil where the black wire from the msd connects. I still have to replumb the fuel system before I can fire the cobra up again and see if it worked.
John(;-)

kris-kincaid · #12 (**permalink**) 10-29-2007, 08:52 AM

John, you DO NOT need a tach adapter. I have never even seen one, and I've built quit a few Shelby's with MSD boxes. I always make up a brand new wire and run it from the male spade TACH OUTPUT on the MSD box (red arrow below) directly to the tachometer input. You will have the green wire unplugged from the tach and in it's place will be the new wire coming from the MSD box TACH OUTPUT. Do not hook the tach up to the (-) of the coil.

MDN · #13 (**permalink**) 10-29-2007, 09:24 AM

Kris is correct, I did this on my car. But I think it also depends on your brand of gauge. The MSD instructions indicate what brand of gauges need an adapter. Ford, Autometer (my gauge) do not, yours may. The list is included in your instruction manual.
Regards,
Mike

kris-kincaid · #14 (**permalink**) 10-29-2007, 10:14 AM

MDN, Shelby uses Autometer almost exclusively.

shelby racer · #15 (**permalink**) 10-29-2007, 09:19 PM

Hey Kris that A LOT! I am sorry for being so thick, but if the green wire goes to the place on the tach that I am going to run a new wire, why (I know - again) can't I just use the green wire???? It makes me feel better that that was the way I had it set up - green wire from tach input in tach from dash to tach output spade connector on the msd - even though i didn't work even though it should have from the msd instructions and the shelby schematics.
John(;-)