Electronic Tach for a HEI Ignition
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Joined: Nov 2004
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Electronic Tach for a HEI Ignition
Just bought my first C3 which is in transit. Its a 1970 modified BB convertible. The previous owner put in a HEI ignition so the Tach is inoperable. I understand that I would need to install an electronic Tach (75-77?). Am I on the right track? Does anyone know where I might find one?
Thanks-
Lou
Thanks-
Lou
Pro
Joined: Mar 2004
Posts: 602
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From: Atlanta GA
Or you can upgrade to an MSD or Mallory tach drive distributor to run the cable drive tach: I started a thread on that a while ago.
I plan to go to MSD, but it's a fairly expensive, so I'm waiting until i build the engine. In the meantime, I just plugged in a cheapo electronic tach and stuck that sucker on the steering column. :o It ain't the look I was going for, but it tells me what I'm spinning . . . cost about $30, and took an evening . . .
I plan to go to MSD, but it's a fairly expensive, so I'm waiting until i build the engine. In the meantime, I just plugged in a cheapo electronic tach and stuck that sucker on the steering column. :o It ain't the look I was going for, but it tells me what I'm spinning . . . cost about $30, and took an evening . . .
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
On my '69 Vert that I owned about 5 years ago, I bought a used 1975 tachometer from
http://www.contemporarycorvette.com
for about $100.. That's a lot less than a $350 tach drive distributor...
http://www.contemporarycorvette.com
for about $100.. That's a lot less than a $350 tach drive distributor...
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
1970 has green numerals and 75-77 has white so it won't match the speedo. The later C3 also has fairly low redlines.
Good news is that you can transplant your original faceplate onto the 75-77 tach. The mounting holes are off just a hair but it is not very noticable at all. I did this on my 71 (last year for green numerals) and it has worked great.
Good news is that you can transplant your original faceplate onto the 75-77 tach. The mounting holes are off just a hair but it is not very noticable at all. I did this on my 71 (last year for green numerals) and it has worked great.
Le Mans Master
Joined: Sep 2003
Posts: 8,812
Likes: 2,029
From: eastern NC
A couple of people have asked about this in the past few weeks. The easiest thing to do if you like and want to keep with the HEI is to get an HEI with the external tach drive. A number of supporting vendors carry them. These are not inexpensive but they are an excellent low maintenance distributor and of course have the added benefit of a mechanical tach drive.
The HEI is a great system, typically inexpensive and makes a excellent upgrade on early smallblocks. The only draw back is of course it doesn't come stock with a tach drive and it will not fit under your original distributor shielding. You can change to an electronic tach, but by the time you buy the tach, get a custom face plate to match your gauges and then install it, the HEI with external tach drive will seem very reasonable.
One other option is to get an original tach drive distributor and convert it to electronic. This will cost about the same and have the added benefit of fitting under your shielding. Keep in mind the HEI distributor does require occasional rebuilding just like the original distributor does. With the exception of no points and condenser, it has all the same basic internal moving parts that wear and corrode just like the points distributor.
GUSTO
The HEI is a great system, typically inexpensive and makes a excellent upgrade on early smallblocks. The only draw back is of course it doesn't come stock with a tach drive and it will not fit under your original distributor shielding. You can change to an electronic tach, but by the time you buy the tach, get a custom face plate to match your gauges and then install it, the HEI with external tach drive will seem very reasonable.
One other option is to get an original tach drive distributor and convert it to electronic. This will cost about the same and have the added benefit of fitting under your shielding. Keep in mind the HEI distributor does require occasional rebuilding just like the original distributor does. With the exception of no points and condenser, it has all the same basic internal moving parts that wear and corrode just like the points distributor.
GUSTO
Burning Brakes
Joined: Mar 2004
Posts: 923
Likes: 4
From: Austin Tx
You can spend $400-500 on an HEI dist with a tach drive or you can get a 75-77 tach on ebay for $70 or less and easily put his faceplate from your 70 on there and be on your way. The mech tachs suck because no matter how much you keep em lubed they bounce and the cables and dist gears wears out. Sounds like a great excuse to convert to elec stock tach.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Originally Posted by Gage
You can spend $400-500 on an HEI dist with a tach drive or you can get a 75-77 tach on ebay for $70 or less and easily put his faceplate from your 70 on there and be on your way. The mech tachs suck because no matter how much you keep em lubed they bounce and the cables and dist gears wears out. Sounds like a great excuse to convert to elec stock tach.
two kinds of mechanical tachs, those that don'e work, and those that shortly will not....
GENE
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Team Owner
Joined: Jul 2004
Posts: 40,412
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From: Redondo Beach, California
There was a posting here a while back by someone who took his early C3 mechanical tach and grafted on the electronic drive from a later year C3. He did it himself. I was pretty easy as I recall. Maybe the article can be found today in corvettefaq.com. Sending the tach out to someone like "Roger" sounds like a really good idea also. (I've had a couple of things redone by Roger and have been very happy.)
I bought one of those HEI distributors that was mod'ed for a mechanical drive pickup. Those things cost something like $500 today I believe. This is really an outrageous price.
I bought one of those HEI distributors that was mod'ed for a mechanical drive pickup. Those things cost something like $500 today I believe. This is really an outrageous price.
Last edited by 68/70Vette; Feb 4, 2005 at 08:40 PM.
Le Mans Master
Joined: Jan 2001
Posts: 6,743
Likes: 1,385
Go with the 75-77 electronic...
I've had both. MSD was a fine distributor and all that, but I should have just gone with electronic tach to begin with. I ended up installing a ramjet 350 with a small cap HEI and I just wired up a 75-77 tach. I recommend the Electronic 75-77 tach.
One thing that annoyed me about the MSD was that it got all rusty inside. AND it's not like my car sits outside or anything. It would also have annoyed me to buy an MSD 6A just to make the distributor work; except that I already had one when I bought the distributor.
One thing that annoyed me about the MSD was that it got all rusty inside. AND it's not like my car sits outside or anything. It would also have annoyed me to buy an MSD 6A just to make the distributor work; except that I already had one when I bought the distributor.
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
There was a posting here a while back by someone who took his early C3 mechanical tach and grafted on the electronic drive from a later year C3. He did it himself. I was pretty easy as I recall.
After 20 + years of being out of the electronic tachometer repair business... I am gettign back into it again.
Email me if interested in a repair - or conversion from mechanical to electronic. I'll beat anyones price on similar work.
tim-yvonne@juno.com
1971, 7577, conversion, convert, corvette, cost, dive, electric, electronic, hei, ignition, mechanical, pointless, tach, tachometer, tachs
