1974 tacho conversion to electronic
Thread Starter
4th Gear
Joined: Oct 2010
Posts: 4
Likes: 0
From: Houston Texas
1974 tacho conversion to electronic
Hey guys, I just got a nice '74 vette. One of the previous owners changed the ignition to electronic. Since '74 was the last year for mechanic distributors, the original tacho is now not working, but he screwed an ugly Monster Tach on the dashboard instead. I would like to try to convert the original tacho to electronic. I was thinking of getting a '75 or later electronic one (probably with the new circuit boards) and somehow swap the dial to my original one. Would that work? (Would it be able to read the signal from the distributor?) Thank you. (I don't know the type of the distributor he put in, but by the coil on the top it looks like a HEI.)
Last edited by bedazs; Oct 22, 2010 at 12:02 AM.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
The original mechanical tachs are terrible if you are looking for accurate tach functions. If you have a quick reving motor they bounce all over when rowing through the gears. On a mild motor it should be fine. I had mine converted by a forum member here for around 150. It works very well and is stable as can be. Yes yo ucan go back t oan old points style distributor and have it rebuilt and fitted with electronics but it will cost yo umore than a tach conversion. Or as you said get a tach from a 75 or later and use the guts. There are plenty of gauge repair facilities if you are not comfortable doing this also.
Thread Starter
4th Gear
Joined: Oct 2010
Posts: 4
Likes: 0
From: Houston Texas
This distributor works well for now, so I'm not thinking about going back to the points style one. I like to try and do stuff on my own, the question I guess would only be if I need to electronically calibrate say a '75 or '76 tacho for the particular distributor, or would it be able to read the signal for any electronic distributor (just using the signal cable that is now in the Monster Tach.)
Burning Brakes
Joined: May 2007
Posts: 1,022
Likes: 33
From: Lokeren, Belgium
Hi there. I did exactly the same thing except the face plate. I used a 75 tach with new circuit board from Willcox but i swapped my original 74 speedo face plate with a 75 one so the font matches (and i needed kmh indication anyway for belgian legislation) one wire to a ground, one to the tach signal on the dizzy and a 12v supply wire coming from a extra fusebox (triggered when key is in on position)
Le Mans Master
Joined: Aug 2003
Posts: 7,720
Likes: 12
From: Chattanooga TN
I bought a '76 tach and put it in. You only need 3 wires-ign switched, tach signal, and ground. Be sure to hunt up a tach filter to go near the distributor. As far as a swap, they are a direct bolt in interchange.
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