Topic: Tach not working
in Forum: C3 Electrical
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Hey all,
The tach on my 72 does not function at all. Any ideas on where I should get started would be greatly appreciated.
Thanks as always!!
The tach on my 72 does not function at all. Any ideas on where I should get started would be greatly appreciated.
Thanks as always!!
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I would first take off the tach cable off the distributor end, sometimes the gear that goes into the dist shaft gets stripped. You can also turn the cable by hand and see if your tach moves. My gear was stripped in mine and after I changed gears it has worked fine ever since!
Good Luck!
Good Luck!
Tom
71 454/365 Mulsanne Blue Convertible 
Thanks Tom I will try that and let you know!
The tach on my 75 has a circuit board mounted on it. The board was bad when I purchased her. I purchased a new circuit board from one of the corvette specialty places, took a weekend and replaced the board. Real easy to change, but just a pain to get to. Is the 72 setup different than the 75?
1975/L48/Coupe/4 Speed(1 of 1057)/Headers/true duals/aluminum intake/holley 750/MSD ignition/roller rockers/
|IMG|http://www.C3VR.com/member_uploads/1701_1800/1717/BSVette75d_sig.jpg |/IMG|
Gold MemberClifton, NJ - USA
Joined: 10/3/2003
Posts: 129
Vette(s): 1972 Coupe
Ontario Orange
Black leather interior
LS-5; Turbo 400
Yes, the 72 is a mechanical distributor driven tach. I beleive that 75 & up have a electronic Tach. I have a 72, and the first thing I did was to completely rebuild the distributor drive, as I experienced a few on the road problems with my 67. It is especially important on those mechanical drive distributors to keep the driven gear well lubricated in its brass adapter, and make sure the spacer button inside the distributor is not missing / worn down. There are a few different approaches to fixes available thru the usual suppliers.
1972 T Top 454; "Boomer" Latest "upgrades": 1 1/8" front Stabilizer bar. Rebuilt SS calipers with O-ring pistons. Under car Chambered exhaust. Fiberglass rear spring (360lbs/in). Bilstein Rear Shocks. 3/4" Rear Stabilizer Bar. Tow hitch. Performer manifold with 600 cfm Holley. Comp Cam 262 .499 lift. L-88 Hood in process
Thanks for the info windrider. I know there are a lot of differences between the early and mid 70's. I know that sometimes the service manual don't help out much, because most these manuals aren't really specific, but very general. 
1975/L48/Coupe/4 Speed(1 of 1057)/Headers/true duals/aluminum intake/holley 750/MSD ignition/roller rockers/
|IMG|http://www.C3VR.com/member_uploads/1701_1800/1717/BSVette75d_sig.jpg |/IMG|
I have the same problem with my '68. So can the tach drive gear be removed and replaced with the distributor in the car? Or does the distributor have to be removed?
Do I have to take the distributor housing apart or just slide out old one and slide in the new?
Steve
Do I have to take the distributor housing apart or just slide out old one and slide in the new?
Steve
Gold MemberClifton, NJ - USA
Joined: 10/3/2003
Posts: 129
Vette(s): 1972 Coupe
Ontario Orange
Black leather interior
LS-5; Turbo 400
The driven gear and adapter can be removed from the distributor houseing without removing the distributor, the Tach drive gear is part of the distributor shaft. To replace this, the distributor needs to be removed.
1972 T Top 454; "Boomer" Latest "upgrades": 1 1/8" front Stabilizer bar. Rebuilt SS calipers with O-ring pistons. Under car Chambered exhaust. Fiberglass rear spring (360lbs/in). Bilstein Rear Shocks. 3/4" Rear Stabilizer Bar. Tow hitch. Performer manifold with 600 cfm Holley. Comp Cam 262 .499 lift. L-88 Hood in process
Hey,
I got in there and removed the tach cable from the distributor. The cable seemed a little tattered but not too bad. I guess I need to remove the whole distributor to see if it is a gear. Is that correct?
As a side not, when I was in there unscrewing the tach cable, my arm brushed past the oil pressure guage where it goes into the engine block. When I started up the car to test if my cable fix worked oil started spewing out where the cable is. I guess I accidentally broke it without noticing. I got it fixed but just a word of warning to any other who ventures in that way. Be careful it was quite a mess!
I got in there and removed the tach cable from the distributor. The cable seemed a little tattered but not too bad. I guess I need to remove the whole distributor to see if it is a gear. Is that correct?
As a side not, when I was in there unscrewing the tach cable, my arm brushed past the oil pressure guage where it goes into the engine block. When I started up the car to test if my cable fix worked oil started spewing out where the cable is. I guess I accidentally broke it without noticing. I got it fixed but just a word of warning to any other who ventures in that way. Be careful it was quite a mess!
in Forum: C3 Electrical
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