Converting Mechanical Tach to Electric
Thread Starter
Melting Slicks
Joined: Mar 2001
Posts: 2,080
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From: Exiled Tampa Bay Misfit
Converting Mechanical Tach to Electric
I have an HEI distributor and an original tach drive tach. I have heard that you can get the guts of a later electrical tach and use the face of your original tach to complete the effect.
So my question is what do I need exactly? Just the circuit board? The metal casing? All of the plastic parts inside of the metal housing? Just want to know what I'm looking for before I go shopping.... :cheers:
Thanks!
So my question is what do I need exactly? Just the circuit board? The metal casing? All of the plastic parts inside of the metal housing? Just want to know what I'm looking for before I go shopping.... :cheers:
Thanks!
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Re: Converting Mechanical Tach to Electric (Monkeywrench)
I did this swap on my 69' (sold).. I bought a electrical 75' tach from Contemporary Corvette for $75 or so... and just used the 75 tach instead of the 69 tach... I didn't change the face plate though.. The letters on the 75 tach were slightly different but it didn't bother me - nor did anyone notice...
:cheers:
Olivier
:cheers:
Olivier
Thread Starter
Melting Slicks
Joined: Mar 2001
Posts: 2,080
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From: Exiled Tampa Bay Misfit
Re: Converting Mechanical Tach to Electric (Alwyn678)
Just drop in a Dual Point Mallory Distributor with Tach drive....Worked for me
Thanks Olivier
[Modified by Monkeywrench, 6:42 PM 12/27/2002]
Le Mans Master
Joined: Aug 2000
Posts: 9,662
Likes: 7
From: Semper ubi, sub ubi
Cruise-In VI Veteran
Cruise-In VII Veteran
Re: Converting Mechanical Tach to Electric (Monkeywrench)
Try http://www.davessmallbodyheis.com they'll convert your old points distributor to HEI for about $175.00. A lot less trouble than trying to find a 75 tach and then betting that it is OK, if it isn't you have to spend another $75.00 for a repair kit. Then you have to pull your dash and put it in. Putting your old face on the tach is not easy, and as was said in earlier post the number are a different color than your old speedometer.
Le Mans Master
Joined: Jul 1999
Posts: 9,206
Likes: 17
From: Sewell NJ
Re: Converting Mechanical Tach to Electric (Monkeywrench)
Why not just put a Pertronix unit in the points distributor and be done with it. Cost is about $70 and you're done changing points forever. I've had mine for at least 5 years and don't even bother to check the dwell anymore because it just doesn't move. It also allows you to keep your shielding because I don't believe an HEI will fit under it. Just my $.02.
Le Mans Master
Joined: May 2000
Posts: 6,493
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From: Bloomington MN
Cruise-In II Veteran
Re: Converting Mechanical Tach to Electric (vettfixr)
If you want to use newer tach internals with an older tach face, that will work fine. A 75-77 tach will allow the use of an earlier tach face. You can buy a small sub-harness from Lectric Limited for 20 bucks that looks like a factory wiring harness. It has the right connectors for the tach and the HEI. I believe Zwede was the guy who told me all about it, you can ask him for the specifics, as I have not done the actual conversion yet (my interior is still out of the car).
AC
AC
Le Mans Master
Joined: Aug 2000
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From: Semper ubi, sub ubi
Cruise-In VI Veteran
Cruise-In VII Veteran
Re: Converting Mechanical Tach to Electric (vettfixr)
I used a Pertronix Ignitor in my old engines tachdrive distributor, I wasn't exactly displeased with it, but it could have been better. I didn't like the 5 second "warm-up" period before starting (reminded me of my old days with a worthless Oldsmobile Diesel) It performed pretty good once the car was started, and is still in my old tach drive distributor. The real problem is that the ZZ4 has a roller cam and therefore it uses a special melonized gear on the distributor. I'm not sure if the gear on the current HEI distributor will fit on my old tach drive distributor, and to tell the truth I haven't gone to the trouble to find a mellonized gear that will fit the old distributor. Does anyone know a GM part number or aftermarket source for the right distributor gear?
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Le Mans Master
Joined: Jul 1999
Posts: 9,206
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From: Sewell NJ
Re: Converting Mechanical Tach to Electric (Smokehouse69)
I think the problem you had was related to the lobe sensor type unit. A lot of guys had the same problem and it was anoying. If you get the original Pertronix with the magnet ring and sensor you don't have any wait at all. I believe the new Ignitor II works the same way but you have to change the resistance wire to a full 12 volt wire to make it work properly. All in all I would recommend the original unit which works just fine with the resistance wire and doesn't have the warm up problem. It's also the cheapest.
Le Mans Master
Joined: Feb 1999
Posts: 6,807
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From: Hoosier
Cruise-In III Veteran
Re: Converting Mechanical Tach to Electric (Monkeywrench)
I haven't done this, so I can't attest to it. But a tech rep at Autometer said I could adapt the face of my 72 tach onto one of their 5 inch tachs without much trouble. I may do this someday when I convert to a HEI.
Team Owner
Joined: Jun 2001
Posts: 43,136
Likes: 155
From: Thomson Georgia
Re: Converting Mechanical Tach to Electric (Monkeywrench)
Just drop in a Dual Point Mallory Distributor with Tach drive....Worked for me
Yeah easy but $$$$$$$$
Thanks Olivier
[Modified by Monkeywrench, 6:42 PM 12/27/2002]
Yeah easy but $$$$$$$$
Thanks Olivier
[Modified by Monkeywrench, 6:42 PM 12/27/2002]
By the way I went the way of Pertronix II and I was sorely disappointed in the results.....Both Modules they sent me fried in less that 2 months. So I decided to go back to tried and true
[Modified by Alwyn678, 9:40 AM 12/30/2002]
Thread Starter
Melting Slicks
Joined: Mar 2001
Posts: 2,080
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From: Exiled Tampa Bay Misfit
Re: Converting Mechanical Tach to Electric (Alwyn678)
I paid 175 bucks at Barnett Racing Brand new...................
[Modified by Alwyn678, 9:40 AM 12/30/2002]
[Modified by Alwyn678, 9:40 AM 12/30/2002]
Team Owner
Joined: Jun 2001
Posts: 43,136
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From: Thomson Georgia
Re: Converting Mechanical Tach to Electric (Monkeywrench)
all one page | printable page
MAA-2648201
Image is a representation of this part. Actual part may vary.
$179.95
Race proven performance
Chevrolet: 1955-96 262-454, dual point, tach drive, distributor
A Mallory dual point distributor can increase coil output by 50 percent. This distributor features stabilized points to eliminate float and bounce, a brass case condenser that eliminates corrosion, self-lubricating bushings, and a super duty cap and rotor to prevent shorting. You can adjust the advance from 16 degrees to 28 degrees.
Sold individually.
Copyright © 2002 by AUTOSALES, INC. dba Summit Racing Equipment
