MSD box/tach help needed

[2000Durahoe]

I just got back from helping my neighbor put an MSD 6AL box on his (my old) ’67 Mustang. We got it all hooked up and running but now the tach isn’t working. It’s an Autometer tach but it was working just fine last weekend when the old setup was on there. We put an MSD 6AL box, MDS coil, MSD cap/rotor, MSD wires, and AC plugs. The car is running great but the tach just isn’t working. Any ideas? We checked and double checked all the connections and routing. Everything seems to be ran right.

 

[igotaneed4speed]

Did you hook the tach to the box or to the coil?

 

[2000Durahoe]

Did you hook the tach to the box or to the coil?

The box

 

[igotaneed4speed]

have you tired hooking it to the coil?



how old is the box used new? etc?

 

[2000Durahoe]

have you tired hooking it to the coil?



how old is the box used new? etc?

We didn't hook it to the coil at all. Wouldn't that say it's spinning 8x greater then what it really is?

The box is brand new. He ordered all his MSD shit from Summit a few weeks ago.

 

[igotaneed4speed]

We didn't hook it to the coil at all. Wouldn't that say it's spinning 8x greater then what it really is?

The box is brand new. He ordered all his MSD shit from Summit a few weeks ago.

no if you hook it to the (-) coil it will read the same as the box.. I perfer it there as the box tab might be slightly delayed compared to the physical colapse time of the coil.


i've seen alot of msd boxes new ans used that the tach output dosent work.

 

[GrandmaLS]

The MSD manual says you may need a tach adapter if the tach doesn't work.

Bottom of page 7, top of page 8

MSD Troubleshooting

 

[igotaneed4speed]

I've never heard of someone using a tach adaptor on a carb'd v8 in my life.

 

[GrandmaLS]

I've never heard of someone using a tach adaptor on a carb'd v8 in my life.

I was just showing him the manual MSD has. I'd try and run it off the coil too.

 

[2000Durahoe]

Thanks for the help guys. I'll relay the information on to him tomorrow. We spent like 3 hours in the garage swapping all that stuff out today so we just called it a day. Plus the beer was running low.

 

[2000Durahoe]

We put it off the coil like you said and it works but it seems like it's low IMO. It's saying it's idling at 500rpm and even when you rap it up it still only hits abotu 3800-3900. The engine was up at like 5k. Any ideas now?

 

[BigWheelinBubba]

Check the 4/6/8cyl setting in the tach and make sure its on the right setting.

 

[2000Durahoe]

Check the 4/6/8cyl setting in the tach and make sure its on the right setting.

I'm sure it's on 8 but even if it wasn't wouldnt that make it run fast? Like if it was at one a 4 cycle but it's on an V8 it woudl stay its idleing at 1,500rpm when it's actually at 750rpm? This thing is reading low right now. Idel is reading 500rpm when it should be about 800rpm and when you rev it up it only goes to like 3,800rpm when you you can hear it's like 5,000-5,200rpm.