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ojh

'67 Gt500 tach signal

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I may have posted this in the wrong section, its duplicated in any event.  I'm working on a '67 GT500 that has been fitted with an MSD ignition, the original tach won't work with the MSD so I bought the MSD adaptor #8920.  The problem is that I don't know if the original tach signal came from the positive or the negative side of the coil and the connection to the adaptor is different (of course, why can't anything be as simple as it should be?).  I have the '67 Mustang Electrical Assembly manual but it doesn't show the tach option.

Anybody on here know how it was connected?  I suspect Shelby did it the same for a bunch of years and models.  

Thanks, Oj

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7 hours ago, ojh said:

I may have posted this in the wrong section, its duplicated in any event.  I'm working on a '67 GT500 that has been fitted with an MSD ignition, the original tach won't work with the MSD so I bought the MSD adaptor #8920.  The problem is that I don't know if the original tach signal came from the positive or the negative side of the coil and the connection to the adaptor is different (of course, why can't anything be as simple as it should be?).  I have the '67 Mustang Electrical Assembly manual but it doesn't show the tach option.

Anybody on here know how it was connected?  I suspect Shelby did it the same for a bunch of years and models.  

Thanks, Oj

You might ask over at the Shelby American Auto Club site that focuses more on the first generation Shelby Mustangs.  I have worked with MSD and the module for my 66 GT350 and followed the instructions and a Youtube video of how to do it.  Runs fine.  The MSD box is not in the engine compartment as it will frequently fail due to heat.  I put it out of sight under the glove box.  It has been a few years so I do not recall all the particulars other than having to splice in some extra wire to reach the box. I will have to look under the hood as to the wire set up.

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6 hours ago, 66GT350PS said:

You might ask over at the Shelby American Auto Club site that focuses more on the first generation Shelby Mustangs.  I have worked with MSD and the module for my 66 GT350 and followed the instructions and a Youtube video of how to do it.  Runs fine.  The MSD box is not in the engine compartment as it will frequently fail due to heat.  I put it out of sight under the glove box.  It has been a few years so I do not recall all the particulars other than having to splice in some extra wire to reach the box. I will have to look under the hood as to the wire set up.

Thanks, I appreciate that.  'Back in day' I crewed for Charlie Kemp, not on his GT350 but the CanAm car, the GT350 is a very special little car, congratulations.

They put the MSD in the trunk of this one.  I'll have a looksee at the SAAC, thanks, Oj

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16 hours ago, ojh said:

I may have posted this in the wrong section, its duplicated in any event.  I'm working on a '67 GT500 that has been fitted with an MSD ignition, the original tach won't work with the MSD so I bought the MSD adaptor #8920.  The problem is that I don't know if the original tach signal came from the positive or the negative side of the coil and the connection to the adaptor is different (of course, why can't anything be as simple as it should be?).  I have the '67 Mustang Electrical Assembly manual but it doesn't show the tach option.

Anybody on here know how it was connected?  I suspect Shelby did it the same for a bunch of years and models.  

Thanks, Oj

 

Why not give the MSD tech line a phone call, thats if you haven't already. Their 888 phone number is shown below.

 

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Thanks, I spoke with them and they didn't know how it was connected.  It seems the tach could be voltage or current triggered, depending on which side of the coil it was connected to.  The adaptor can connect either way.  As usual things are always more complicated than they should be.

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12 hours ago, 66GT350PS said:

You might ask over at the Shelby American Auto Club site that focuses more on the first generation Shelby Mustangs.  I have worked with MSD and the module for my 66 GT350 and followed the instructions and a Youtube video of how to do it.  Runs fine.  The MSD box is not in the engine compartment as it will frequently fail due to heat.  I put it out of sight under the glove box.  It has been a few years so I do not recall all the particulars other than having to splice in some extra wire to reach the box. I will have to look under the hood as to the wire set up.

Do you remember if you used the 'violet' wire from the adaptor box?  Whether that was is used or not will tell me how to connect the other wires, thanks Oj

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