Need some help converting to electronic tach
Thread Starter
Le Mans Master
Joined: May 2000
Posts: 6,493
Likes: 6
From: Bloomington MN
Cruise-In II Veteran
Need some help converting to electronic tach
Well, I took the plunge and bought an HEI distributor. I didn't spend the big bucks and get one with tach drive, so obviously I need to use an electronic tach. What parts will I need? The options are to install a later year tach (are the colors and styles of the numbers the same?), or install a later model tach into my 69 tach face, or go with an aftermarket in dash tach and speedo (I would replace both so they would look the same). I am wondering what are the benefits/drawbacks to each of those solutions, such as cost, ease of installation, and appearance? Appearance being the most important. Thanks :cheers:
AC
AC
Racer
Joined: Feb 2001
Posts: 377
Likes: 0
Re: Need some help converting to electronic tach (A C)
A/C.....how come? Why not a Petronix unit or something like that. Won't the tac and speedo talley up to the price of the big bucks dist. You or Lars could've rebulit the old one.
Thread Starter
Le Mans Master
Joined: May 2000
Posts: 6,493
Likes: 6
From: Bloomington MN
Cruise-In II Veteran
Re: Need some help converting to electronic tach (Jon69L46)
I got the HEI for a couple of reasons....one of which is so I can use my mini starter without having to add a relay. I already have a Mallory Unilite conversion (which works fine), but I can't use a two wire starter solenoid with it. Also, the HEI's I have seen with tach drive are around $500 :eek: , whereas the non tach drive HEI from GM Performance parts is only $200
AC
[Modified by A C, 5:57 PM 9/21/2001]
[Modified by A C, 5:58 PM 9/21/2001]
AC
[Modified by A C, 5:57 PM 9/21/2001]
[Modified by A C, 5:58 PM 9/21/2001]
Race Director
Joined: Sep 1999
Posts: 11,358
Likes: 379
From: Plano TX
Re: Need some help converting to electronic tach (A C)
AC:
The colors of the numerals changed in '72. The tach you need is 75-77. Take the faceplate off and use your old faceplate. You will then get the correct greenish numerals and the right redline.
Wiring is simple, just 3 wires. Ground, 12V switched and tach. Connect the 12V switched to another gauge (only on when ign key on).
I did the swap a few years ago on my '71 and I'm very, very happy with it. HEI's never give a lick of trouble.
Also be sure to get rid of the factory resistor wire to the coil. Trace it back to the fuseblock (engine side of the firewall) and replace it with a 12-14 gauge regular wire. This is the wire that goes to the 'bat' terminal on the HEI.
Also don't forget to get the right plugwires.
The colors of the numerals changed in '72. The tach you need is 75-77. Take the faceplate off and use your old faceplate. You will then get the correct greenish numerals and the right redline.
Wiring is simple, just 3 wires. Ground, 12V switched and tach. Connect the 12V switched to another gauge (only on when ign key on).
I did the swap a few years ago on my '71 and I'm very, very happy with it. HEI's never give a lick of trouble.
Also be sure to get rid of the factory resistor wire to the coil. Trace it back to the fuseblock (engine side of the firewall) and replace it with a 12-14 gauge regular wire. This is the wire that goes to the 'bat' terminal on the HEI.
Also don't forget to get the right plugwires.
Race Director
Joined: Sep 1999
Posts: 11,358
Likes: 379
From: Plano TX
Re: Need some help converting to electronic tach (A C)
Plugwires are already ordered :D . I need a tach filter also, correct?
AC
AC
Thread Starter
Le Mans Master
Joined: May 2000
Posts: 6,493
Likes: 6
From: Bloomington MN
Cruise-In II Veteran
Re: Need some help converting to electronic tach (zwede)
Am I correct in assuming all I need to buy would be a 75-77 tach rebuild kit? Do they make these for electronic tachs? I am actually having a hard time finding 75-77 tachs online (go figure :confused: ).
AC
[Modified by A C, 5:38 PM 9/22/2001]
AC
[Modified by A C, 5:38 PM 9/22/2001]
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Burning Brakes
Joined: Dec 1999
Posts: 845
Likes: 0
From: Ventura Harbor CA California
Re: Need some help converting to electronic tach (A C)
No, you need to buy the electronic tach from a 75 to 77. They are no longer produced and unless Joe Lucia knows of a warehouse some where you'll have to go to a salvage yard. Mine came from http://www.nos.net/davato/corvette.htm
:flag
:flag
Thread Starter
Le Mans Master
Joined: May 2000
Posts: 6,493
Likes: 6
From: Bloomington MN
Cruise-In II Veteran
Re: Need some help converting to electronic tach (7Bob3)
All I wanted to do is put on a high torque mini starter....why is this becoming a major ordeal? :boxing
Don't answer that...I have been down this road before. :lol:
Thanks Bob
AC
Don't answer that...I have been down this road before. :lol:
Thanks Bob
AC
Race Director
Joined: Sep 1999
Posts: 11,358
Likes: 379
From: Plano TX
Re: Need some help converting to electronic tach (A C)
I know Gary Gruhala had 2 in stock a few weeks ago. Don't remember his webpage but a google should find it. (search for "gruhala enterprises").
Drifting
Joined: Jul 2001
Posts: 1,527
Likes: 0
From: Tucson AZ
St. Jude Donor '11,'13
Re: Need some help converting to electronic tach (A C)
I just went through the same thing when I installed a crate engine in my '70. Get yourself a late model (74/75 and install it in your dash. If the is different very carefully remove the needle annut and replace the face. Then run yourself a source wire (juice) from the tqach to the distributor and you got. I got quotes from 500 to 900 for doing machine work to the tach drive to convert it. Very simple to do and save a lot of grief and $$$. Good luck.
