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Tach Conversion

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Old Dec 7, 2015 | 01:04 PM
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Default Tach Conversion

Will a tach electronic conversion, like Corvette Central sells, work with a MSD 6AL box? My '69 has an HEI distributor that is way too big and hits the wiper motor. Just a matter of time before something breaks. I have a MSD billet distributor but does not have the tach takeoff. If I use the distributor then I have to use one of MSD boxes, most likely a 6AL. The new 6AL is digital and has a rev limiter built-in. All of this will require the tach to be converted. Just want to make sure the tach will work with the MSD box. Other option is to buy the MSD distributor with the mechanical tach connection, about $390, and still install the MSD 6AL box. But this would allow to keep the tach as a mechanical unit.

Thanks for your help and opinions!

Gus
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Old Dec 7, 2015 | 01:17 PM
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Originally Posted by SideWinder3355
Will a tach electronic conversion, like Corvette Central sells, work with a MSD 6AL box? My '69 has an HEI distributor that is way too big and hits the wiper motor. Just a matter of time before something breaks. I have a MSD billet distributor but does not have the tach takeoff. If I use the distributor then I have to use one of MSD boxes, most likely a 6AL. The new 6AL is digital and has a rev limiter built-in. All of this will require the tach to be converted. Just want to make sure the tach will work with the MSD box. Other option is to buy the MSD distributor with the mechanical tach connection, about $390, and still install the MSD 6AL box. But this would allow to keep the tach as a mechanical unit.

Thanks for your help and opinions!

Gus

I think you can use a 1970/1971 wiper motor to solve your clearance problem. I have a '68 and a '71 and the wiper motors are made very different as my '71's HEI easily clears it's wiper motor.
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Old Dec 7, 2015 | 01:22 PM
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Yes, the MSD6 tach output is compatible with a C3 electric tach. You may, or may not, need a tach filter. If the tach bounces around and doesn't give you a steady reading you need the filter.
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Old Dec 7, 2015 | 01:39 PM
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Zwede

I not asking about changing to a later C3 electric tach. I'm thinking about adding the conversion devise to my existing tach that changes it from a mechanical tach to a electric tach. The devise connects to the rear of the existing mechanical tach.

Sorry for the confusion!

Gus
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Old Dec 7, 2015 | 09:42 PM
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Default Tach conversion.

Originally Posted by SideWinder3355
Will a tach electronic conversion, like Corvette Central sells, work with a MSD 6AL box? My '69 has an HEI distributor that is way too big and hits the wiper motor. Just a matter of time before something breaks. I have a MSD billet distributor but does not have the tach takeoff. If I use the distributor then I have to use one of MSD boxes, most likely a 6AL. The new 6AL is digital and has a rev limiter built-in. All of this will require the tach to be converted. Just want to make sure the tach will work with the MSD box. Other option is to buy the MSD distributor with the mechanical tach connection, about $390, and still install the MSD 6AL box. But this would allow to keep the tach as a mechanical unit.

Thanks for your help and opinions!

Gus
I ran a wire from the 6AL box to a 76 tach in my 69 with no issues.
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Old Dec 7, 2015 | 09:54 PM
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The conversion kits pretty much do away with all the old stuff in the tach. So it is all electronic. Yes I have converted a few cars over with a CD box and they work fine with the tach lead off the CD box.
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Old Dec 8, 2015 | 09:23 AM
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Originally Posted by SideWinder3355
Zwede

I not asking about changing to a later C3 electric tach. I'm thinking about adding the conversion devise to my existing tach that changes it from a mechanical tach to a electric tach. The devise connects to the rear of the existing mechanical tach.

Sorry for the confusion!

Gus
Why not switch the guts over to electric and keep your face plate? I did this on my '71, except switched to a 6000 rpm redline face plate from a '69. Looks factory but works much better than the mech tach ever did.
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Old Dec 8, 2015 | 09:38 AM
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Thanks for the help!! I will go with the electronic unit and put the 69 face plate on it. I just pulled my tach and it is bad. Hasn't had a cable attached to it in years and the input will not turn. I might be able to salvage the face plate but the rest is history.

Again, thanks for the help. This is my first Vette and I'm on a steep learning curve!! Couldn't do it without your help.

Gus
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Old Dec 8, 2015 | 01:47 PM
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Will a tach out of a 76 or 77 fit my tach bezel without modification? What year is the best for the conversion. I'm going to have to buy a new tach so I might as well get what works best.

Thanks

Gus
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Old Dec 8, 2015 | 02:00 PM
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75-77 fits.
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