In desperate need of Gage cluster info

danimaltheanima · Dec 15, 2003

I have a 78 Cobra V8 with the 80mph cluster. On the back of the RPM gage there is a black plug. My old RPM gage is broke so I need to use the new one. I can't swap. If it worked I would have done that already.

I had bought a 120mph cluster off Ebay in which came off a V6 I was told. The black plug on the back of the RPM gage is differant than the V8 80mph cluster. As a matter a fact this new 120mph gage cluster didn't come with that black plug but I matched my 80mph plug up to it and the lil notch on the plug is differant.

What do I have to do in order to get this RPM gage to work properly on this 120mph cluster in which was from a V6 to work in my V8 car. Could I snip the two wires on the old pod and soder in new RPM gage into the old pod and just install that into the 120mph cluster.

There has got to be someone out there that knows what I'm talking about and can help me. Somone has had to of taken there 80mph cluster out of there V8 car and put this 120mph cluster into it.

Please someone help me with this problem. My e-mail is danimal@imaxx.net

Thank you

Dan Edwards

78CobraII · Dec 15, 2003

Dan,

The V8 Tach is the same as the I-4 tach, but uses a small electronics box on the back that reduces the signal by 1/2. I guess that this the black plug you are referring to.

The V-6 tach is a unique animal and won't work with the V8 engine, even with the signal reducer.

I don't see why the V8 tach from the 80mph cluster could not be moved to the earlier 120mph cluster...as long as the signal adapter is re-installed.

78CobraII

THE COBRAMAN · Dec 15, 2003

78CobraII said:
Dan,

The V-6 tach is a unique animal and won't work with the V8 engine, even with the signal reducer.

78CobraII

Incorrect. The 6 uses the gray (4th)wire, whereas the 2.3 and 302 do not. It terminates (ground)on the left fender apron.

I have a V6 (D5Z)tach (with D5Z signal box)on my 302 car, works fine.

The gray wire is present in all underdash harnesses I have examined, but is only present in 2.8 engine harnesses. I do recall that it changes color at the firewall connector.

THE COBRAMAN · Dec 15, 2003

danimaltheanima said:
What do I have to do in order to get this RPM gage to work properly on this 120mph cluster in which was from a V6 to work in my V8 car. Could I snip the two wires on the old pod and soder in new RPM gage into the old pod and just install that into the 120mph cluster.

There has got to be someone out there that knows what I'm talking about and can help me. Somone has had to of taken there 80mph cluster out of there V8 car and put this 120mph cluster into it.

Please someone help me with this problem. My e-mail is danimal@imaxx.net

Thank you

Dan Edwards

I already posted on your other thread on this subject, but here goes again:

You need the matching signal box for the tach you're going to use. Swapping wires around or bypassing the index notch on the tach/box WILL NOT WORK, as there are differences in the board/component layout between each family.

If you're running Duraspark ignition, you'll need a D7Z signal box for the original D7Z tach. If you're using a D5 tach, you'll need a D5Z signal box, which comes in blue, white, or black housings. Black and blue are for Duraspark, I believe the white housings were used on breaker-point ignitions. Some of the D5 info is from memory, as my reference material is inaccessable at the moment.

If you have a D4Z tach you're trying to use, toss it. It won't work on harnesses other than '74.

I'd still test the tach first.

BTW, there should be 4 terminals on the tach, 3 terminals in the tach box.

danimaltheanima · Dec 16, 2003

tach

Ok so to make this tach in which is a D5Z tach on my 302 all I need is the D5Z signal box. My old tach in which doesn't work is a D7Z with the D7Z signal box so thats all useless. But does the back side of the signal box in which plugs into the harness under dash plug directly into the D5Z signal box if it was intended for a D7Z signal box plug in. Is the D7Z and the D5Z the same configuration as far as the pluggin to the under dash harness?

THE COBRAMAN · Dec 16, 2003

danimaltheanima said:
Is the D7Z and the D5Z the same configuration as far as the pluggin to the under dash harness?

No. You'll need a D5 pigtail and you'll have to pin out the connector.

Have you tested the tach plugged directly to the harness yet?

Test it. It's very unlikely that the tach and the box are both bad.

danimaltheanima · Dec 16, 2003

Ok this is the thing. I am still in the middle of building the car so its not yet up and running. So being able to hook anything up to actually test my new tach is impossible. My old tach is broken I know that for sure cuz the needle doesn't work. If you move the needle it stay where you stop your fingure and doesn't go back to 0. My old D7Z signal box works fine. I suppose the only thing I need to really get this thing working fine is a D7Z tach with the attatched white pod it sits in and I'd put that into my 120mph cluster.

zwhitr · Dec 16, 2003

Desperate need of Gage cluster info

danimaltheanima said:
Ok this is the thing. I am still in the middle of building the car so its not yet up and running. So being able to hook anything up to actually test my new tach is impossible.

Read subject line Desperate need "I think not"

Power Surge · Dec 16, 2003

Brian, the cluster I got from you has a D7-BB tach, and I have a D7 signal box. I assume that's a match. The stock tach that is in the 78 80mph cluster is a D7-BC, the only difference I can spot from the D7-BB is that the BC has the half-thousand increments on it. Dan, if you need a D7 tach, you can have mine for $10 plus shipping.

zwhitr · Dec 18, 2003

THE COBRAMAN said:
I already posted on your other thread on this subject, but here goes again:

If you're using a D5 tach, you'll need a D5Z signal box, which comes in blue, white, or black housings. Black and blue are for Duraspark, I believe the white housings were used on breaker-point ignitions. Some of the D5 info is from memory, as my reference material is inaccessable at the moment.

QUOTE]

Hey Cobraman my box is white D5Z and its an original 76 Cobra II with v/8 duraspark

dan--I have since converted to autometer tach So I no longer need it I sent you a PM

z

THE COBRAMAN · Dec 18, 2003

Looks like the white box is for '75 and '76; the blue box is for '77,; and the black box is for late '77 and '78.

I haven't had any open in a while, but I know that the boxes won't work with the "wrong" tach. Had to go through quite a few sets to finally come up with a matching working set after my original died.

BTW, the OE supplier for the signal box can't help with any information on them. Claim it's "obsolete". The nerve. :damnit:

In desperate need of Gage cluster info

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