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67 tach wiring dillema part2

6

67390GT

New Member
So I switched the ends on the tach wires, hooked it up started the car and the tach immediately pegged
to 6000, but the car kept running ok. Does this mean the tach is nfg? probably, right
 
I hooked the red wire from the tach to the red/yellow stripe(ign) harness wire and the tach black wire to the pink resistor wire. But like I mentioned before when I got the tach it was wired the opposite, so I switched the male and female ends. I just wonder what would happen if I switched them back......I am afraid of cooking something (or everything)
 
Yeah, I would switch them back as a test. I wouldn't run your tach like it is wired for very long.
 
I've got to attend to a few other things, but I will get back to this thing, do some more checking. One thing that bothers me is: Why am I going through 2 resistances? wiring goes through tach to resistor wire than to ballast resistor than coil. Is that correct? doesn't sound right. I know that's not the problem since 2 resisti would, if anything, make the tach read low.
 
"67390GT" said:
I've got to attend to a few other things, but I will get back to this thing, do some more checking. One thing that bothers me is: Why am I going through 2 resistances? wiring goes through tach to resistor wire than to ballast resistor than coil. Is that correct? doesn't sound right. I know that's not the problem since 2 resisti would, if anything, make the tach read low.
Click to expand...
You either need the resistor wire or the ballast resistor on the coil, but not both. The tach is a current sensing device, and having two resistors in series would lower the current, probably making the tach read low.
 
You sure you didn't have your foot to the floor revving the engine? *G*

Seriously, try hooking the tach up "backwards" for a second or so and see what happens. Something is amiss that isn't apparent visually, probably inside the tach housing.
 
Yeah, im going to try hooking it up 'backwards', but right now ive got it all back together(except the tach)so I'll have to pull the cluster out again -pita.
How else, besides the tach, would the 'double' resistance affect the car?
I figure the tach must be shorted internally - bypassing something; if it was external, the car wouldn't run. I am no electrical guru, so even if I saw a wiring diagram of the tach internals, I wouldn't know what to look for and I am in the top 5 for poor soldering technique. Tachman, here I come.....
 
Double resistance wire: lower voltage at the coil, possibly low enough to produce poor spark and thus poor performance. Some aftermarket dizzies require a voltage greater than some value; if the voltage drops enough, the car will die, most likely when the car gets warm and you're out in a bad neighborhood.

If you do have the pink resistor wire, dump the coil ballast resistor.
 
Si I hooked up the tach 'backwards' and it did the same thing: car started and tach pegged at 6000. I guess that pretty much confirms some kind of short in the tach itself; current passing through it bypassing whatever circuit it needs to go through in order for the tach to work correctly. I guess I should have predicted that.
Now, onto the flickering lights ......... :rr
 
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