Tach Drive Distributor
Thread Starter
Advanced
Joined: Jun 2009
Posts: 66
Likes: 1
From: Akron Ohio
Tach Drive Distributor
I have a '73 Vette that had its distributor replaced with a non tach drive distributor. I sure would like to have it replaced with one that will drive the tachometer. Is there a consensus on what type would be best?
Any info would be helpful
Any info would be helpful
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
Up Grade to HEI
Check E Bay for a replacement HEI distributor with a tach drive. They work and are ridiciously cheap...about $125.00 or there abouts...You cant go wrong with these distributors. The competitions distributors are nearly double and could be the same ones with a different color cap....There is a E Bay seller.....
Instructor
Joined: Mar 2009
Posts: 187
Likes: 1
From: WA
I was thinking about buying this one through Summit, but now I'm considering pulling all the gauges and going electric to them all, so who knows what I'll eventually do.
http://www.summitracing.com/parts/MSD-8572/
http://www.summitracing.com/parts/MSD-8572/
Thread Starter
Advanced
Joined: Jun 2009
Posts: 66
Likes: 1
From: Akron Ohio
Check E Bay for a replacement HEI distributor with a tach drive. They work and are ridiciously cheap...about $125.00 or there abouts...You cant go wrong with these distributors. The competitions distributors are nearly double and could be the same ones with a different color cap....There is a E Bay seller.....
http://cgi.ebay.com/ebaymotors/Corve...1%7C240%3A1308
Pro
Joined: Jul 2004
Posts: 708
Likes: 61
From: Waterford CT
The answer is YES! If you buy the tach drive HEI from e-bay you will have an electronic version with no points. I bought one a couple years ago for about $150 from e-bay and it worked perfectly in my '73.
Racer
Joined: Apr 2007
Posts: 492
Likes: 3
From: Temecula CA
I put an E bay unit in my 72. Works perfect and a bargain price. Just run a good 12 volt power source with a large gauge wire. I ran the hot wire directly from the fuse block. It has adjustable vacuum advance, but it was perfect out of the box after I set the initial timing. I highly recommend it!
Temvette72
Temvette72
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Drifting
Joined: Apr 2007
Posts: 1,970
Likes: 45
From: Cameron Park CA
All the above advice about using a tach drive HEI distributor is excellent. The only caveat I would offer is that if you ever plan to have your car judged on originality, you will have points deducted for a non-original part. Ugh! I can't believe I'm saying to use a points distributor! Just something to consider as you replace the distributor.
Pete
Pete
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
get the e bay unit.....
Melting Slicks
Joined: Mar 2006
Posts: 3,456
Likes: 102
From: Piedmont Va
St. Jude Donor '11-'12-'13,'19-'20
Ditto. Best deal out there and performs flawlessly! 
Terrorizing Orange Cones
Joined: Oct 2007
Posts: 2,572
Likes: 17
From: Northern CO
This is one subject I can straddle both sides: mech drive and electronic.
I've always run wired tachs with no problems. They work great and keep me informed.
When I bought my '72, I inherited a non-OEM distributor (Mallory Unilite) with a mech tach drive and connected to an MSD 6AL box. Cool. It too, works great.
First mech drive I ever owned and maybe it's just the thought there's a cable spinning instead of a wire sending pulses that reminds me of old-school race cars.
These old Corvettes had some fascinating engineering developed into them. I love this stuff (but only when I'm not mutterin' bad words under my breath over another PITA issue).
I've always run wired tachs with no problems. They work great and keep me informed.
When I bought my '72, I inherited a non-OEM distributor (Mallory Unilite) with a mech tach drive and connected to an MSD 6AL box. Cool. It too, works great.
First mech drive I ever owned and maybe it's just the thought there's a cable spinning instead of a wire sending pulses that reminds me of old-school race cars.
These old Corvettes had some fascinating engineering developed into them. I love this stuff (but only when I'm not mutterin' bad words under my breath over another PITA issue).
Pro
Joined: Oct 2004
Posts: 573
Likes: 0
From: Stafford VA
Can the ebay tach drive distributor be changed to a bronze gear for a mechanical roller cam? I know I can order the bronze gear for other distributors, just don't know if they are all the same.
Last edited by UBETRUN; Jul 1, 2009 at 09:19 PM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,113
From: Crossville TN
Perhaps you should test out the (mechanical) tach in your car to make sure it works before buying a tach drive distributor. If the cable is still attached, just hook a small cordless drill's chuck up to the other end of the cable. Run it at a very slow speed until you determine if you are rotating the correct direction. Reverse if necessary. Then run slow again and watch indicator as you increase speed. It should be smooth, steady at a constant drill speed, and work throughout it's range. If the tach doesn't work, then you have to decide whether to fix the mechanical one or switch to electric.
Thread Starter
Advanced
Joined: Jun 2009
Posts: 66
Likes: 1
From: Akron Ohio
Perhaps you should test out the (mechanical) tach in your car to make sure it works before buying a tach drive distributor. If the cable is still attached, just hook a small cordless drill's chuck up to the other end of the cable. Run it at a very slow speed until you determine if you are rotating the correct direction. Reverse if necessary. Then run slow again and watch indicator as you increase speed. It should be smooth, steady at a constant drill speed, and work throughout it's range. If the tach doesn't work, then you have to decide whether to fix the mechanical one or switch to electric.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,113
From: Crossville TN
I think it's clockwise; but to be honest, I can't remember for sure. But running the drill at low speed the wrong way should not do any damage...that would just simulate backing-up (which should free-spin, rather than moving backwards).
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
All of the tachdrive hei I've seen are clones of GM hei which has 0.491" diameter shaft. You'd best ask the ebay seller for dimensions. You'd best do some searching on gear material. And you'd best ask your cam maker what kind of gear other than bronze can be used with your cam. Street cars should avoid bronze & avoid polymer if at all possible. Most cams (billet steel & iron) can use melonized GM gear p/n 10456413 which fits 491 shaft. There's been lotsa threads on this very matter ... search. That's the straight dope ... ask the suppliers when they aren't itching to sell ... you'll likely gets lotsa different opinions here & some aren't well grounded in practical experience.