Topic: tach problems
in Forum: C3 Electrical
Already a Member?
Click Here to Login
Not yet a Member?
Click Here to Register for Free!
SPONSOR AD:: (Our Sponsors help support C3VR)

Hot Springs, AR - USA
Joined: 4/24/2004
Posts: 3236
Vette(s): 69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans
1972 ??
i thought 72 still had a tach drive gear..
maybe im smoking crack but im pretty sure 72 shouldnt have an electric tach.
have you converted it to hei ? and changed the tach out..
i thought 72 still had a tach drive gear..
maybe im smoking crack but im pretty sure 72 shouldnt have an electric tach.
have you converted it to hei ? and changed the tach out..
I didn't change it out but I couldn't find a cable running anywhere. I will do a double check. This car is a '72 frame with a '80 body. as far as I know and can find out I have the original dash and shifter. I have some pics but I don't know how to attach them. How can I post a pic ? 


Hot Springs, AR - USA
Joined: 4/24/2004
Posts: 3236
Vette(s): 69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans
as for posting pic
goto support/comments forum... there are a few locked threads telling you how to do that.
as for distributor.. it would be best to get us a pic..
a 72 should have a gear driven cable tach.
and 80 will have an electrical..
is your coil on the distributor cap or is it a seperate cylinder mounted on the intake.
it really sounds like you have a strange 72/80 hybrid..
it also sounds like you have an 80 tach and distributor
goto support/comments forum... there are a few locked threads telling you how to do that.
as for distributor.. it would be best to get us a pic..
a 72 should have a gear driven cable tach.
and 80 will have an electrical..
is your coil on the distributor cap or is it a seperate cylinder mounted on the intake.
it really sounds like you have a strange 72/80 hybrid..
it also sounds like you have an 80 tach and distributor

HOWELL, NJ - USA
Joined: 5/18/2004
Posts: 6812
Vette(s): 1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.
It appears to be that if you replaced a wire between the distributor and the tach, you have an elctrical tach run off what I assume is an HEI distributor. You may have blown the printed circuit board connected to the back of the actual guage. Was the wire you replaced going into the dist cap? If you used too large a guage of wire, that could have easily over-juiced the PC board. Also, is there a tach filter between the wiring harness and the connection to the distributor? It looks like a large radio supressor.
Let us know what you find.

Let us know what you find.








LukesVette Homepage
Veteran of Operation Iraqi Freedom
101st Airborne(AirAssault!)
God Bless America
Support Our Troops
My guess is you have the newer distributor and tach as well.
But I have to make a correction. Yes too much amperage will cause anything to burn out. But using a larger wire will not.
If a wire is too small it can't handle the amperage going through it an it will burn up. But the current through a wire is not determined by the wire, unless it's a resistance wire.
What determines the flow, assuming the wire is large enough, is the device drawing the current. If it pulls 1 amp, it is going to pull 1 amp on a small, medium, large, or welding cable wire. Larger wire will not increase amp flow.
So why use smaller wires for smaller circuits? It's less bulky, less expensive, and lighter weight. All 3 are very important in a car.
But I have to make a correction. Yes too much amperage will cause anything to burn out. But using a larger wire will not.
If a wire is too small it can't handle the amperage going through it an it will burn up. But the current through a wire is not determined by the wire, unless it's a resistance wire.
What determines the flow, assuming the wire is large enough, is the device drawing the current. If it pulls 1 amp, it is going to pull 1 amp on a small, medium, large, or welding cable wire. Larger wire will not increase amp flow.
So why use smaller wires for smaller circuits? It's less bulky, less expensive, and lighter weight. All 3 are very important in a car.
in Forum: C3 Electrical
SPONSOR AD: (Our Sponsors help support C3VR)