| FAQ |
| Members List |
| Social Groups |
| Calendar |
| Search |
| Today's Posts |
|
#1
05-16-2005, 01:34 PM
|
|||
|
|||
What mods if any do I need to do to tach signal from an HEI dist to get my hood tach to run properly? I do know the signal with HEI is different that points. Some kind of Filter?
Thanks, |
|
#2
05-16-2005, 02:09 PM
|
||||
|
||||
|
My hood tach has 3 wires.
1-From tach to HEI distributor "Tach" Lead 2-Ground 3-Keyed power (From wiper motor on mine) Bob
__________________
67 GTO Hardtop |
|
#3
05-16-2005, 07:57 PM
|
|||
|
|||
|
Yes I know 3 wires. Ground, rev signal, power. But HEI send different signal than points style dist. Will I damage the factory tach or will it not work if I use it as is? Need a Sparky for information.
|
|
#4
05-16-2005, 08:41 PM
|
||||
|
||||
|
Welcome. It should work; at worst it may need a recalibration.
George
__________________
"...out to my ol'55, I pulled away slowly, feeling so holy, god knows i was feeling alive"....written by Tom Wait from the Eagles' Live From The Forum |
|
#5
07-22-2005, 05:02 AM
|
|||
|
|||
|
i have the same question for my GTO 70,she is equipped with the original hood tach,but i don't know if i can just connect the tach wire to the tach connection of the HEI distributor ?
does it work normally or buy an electrical adaptater ? sorry for my french language. |
|
#6
07-22-2005, 09:00 AM
|
|||
|
|||
|
I'll go with George ! My 67 GTO worked fine with HEI. The only issue I had was going to the MSD 6Al box, this required a TACH Adapter. It Will Work * If It Does Work ?
|
|
#7
07-28-2005, 05:11 AM
|
||||
|
||||
|
Goatmon, what kind of adapter? My friend has a hood tach on his 71 and is having problem with it, he has an MSD on it.
|
|
#8
07-28-2005, 08:35 AM
|
||||
|
||||
|
The MSD is a capacitive-discharge type of ignition. The coil connections in this system are MSD output and ground.
At firing time, the MSD box discharges a 400 volt (approx) capacitor to the coil. Ths signal at the coil thus is a positive-going voltage of say, 400 volts, and probably oscillating, that's probably where they get the "multiple sparks". A conventional system (points, HEI, Pertronix, Unitlite...) is a inductive storage discharge, one side of the coil is connected to the battery supply, and the other coil terminal is alternately grounded and then opened (no connection). The tach signal is taken from the switched side of the coil. So all this means that the MSD coil signal is much different from what a standard tach expects (and what a inductive ignition delivers). Hence a adapter is needed for a conventional tach working with MSD. george
__________________
"...out to my ol'55, I pulled away slowly, feeling so holy, god knows i was feeling alive"....written by Tom Wait from the Eagles' Live From The Forum |
|
#9
08-02-2005, 07:44 AM
|
||||
|
||||
|
Does MSD have this adapter? or is it from another manufacture?
|
|
#10
08-02-2005, 11:07 AM
|
||||
|
||||
|
I believe MSD has the appropriate adaptor.
George |
| Reply |
|
|
The PY Online Forums is the largest online gathering of Pontiac enthusiasts anywhere in the world. Founded in 1991, it was also the first online forum for people to gather and talk about their Pontiacs. Since then, it has become the mecca of Pontiac technical data and knowledge that no other place can surpass.
Linear Mode
