We used an inductive soldering iron held near the HEI module to induce a 60 hz magnetic signal into to the pickup coil. With a spark test, it would fire 30 times a second or half to the magnetic field as is reversed. I would try a coil of wire if you have a soldering gun. It won’t work with a pencil type soldering gun. Or, run a jumper off a running GM with HEI, from the tach lead to the tachometer. You just need power, ground and input which was optional on most. It could be a 6 cylinder as it still reads. Unfortunately I don’t live nearby or I could loan my Kent-Moore frequency generator. It has multiple out puts to check VSS input, ABS as seen on scan tool and many other on-off circuits directed by the service manual. Note; Some digital tachs require a “Pull-up” resistor to B+ and increase signal strength. Just a thought.
Thanks, ive heard of using an old 12 charger as it still has 60 hz onthe dc ……i should have bought a freq gen 30 years ago, lol inever thought id use one again…til next time….thanks
@@skipprice6843 I had to laugh a little when I read the little line of your post in my notification list. I pictured a full sized battery charger weighing 60 lbs. held up near a distributor. LOL! I am sure a couple of jumper wires connecting your unknown tach onto a running HEI vehicle. Yes, many are coil over or coil near plug, but a tach signal terminal is a simple 1/4 male spade that a female 1/4” terminal will plug into. This would be easiest to do as a factory tach from a vehicle 8 cylinder engine will simply need ground, B+ and input signal. So barrow a signal from uncle Joe. Not the one in the White House! Just a person you know because it can’t hurt or damage anything. If you remember when they had Sear’s, but Radio Shack sold a spool of meter wire. Red & Black but a package of alligator clips (unless over seas, call crocodile clip) but soft silicone jacket over low oxygen copper wire made great jumper wires. I still have a 4 ft, 8 ft, 12 ft with soldered ends and shrink tubing on ends. I have spool of 3M 5/16” shrink tubing on 50 ft roll on large cardboard sleeve. I said I enjoy electrical. As any wire will do, just buy or make some. If I am testing a fuel pump or tank sending unit voltage drop I need a long jumper to battery. Now I know exactly what voltage is, if I have a good ground (voltage drop) then I see a rusted metal filter, I change it. I drain it in solvent tank, but blow thru it and note plugged or not. Fused jumper (15amp) at relay center as GM had green terminal or pump direct line then place amp clamp over it! 7.5 amps normal. (Tip: head lamp is 4 amps, solder jumpers to plug into vehicle harness. Dim, power or ground problem. Bright, all is good) But using the primary scope or lab scope shows amperage waveform. If jagged, pump is worn at brushes or commutator plates on armature down to plastic) So if current is low, pump is worn. Current is high, restriction or plugged filter) easy and quick.
Great advice on polishing the plastic. I am probably a few weeks away from this phase, but this was a great video for what to expect.
We used an inductive soldering iron held near the HEI module to induce a 60 hz magnetic signal into to the pickup coil. With a spark test, it would fire 30 times a second or half to the magnetic field as is reversed. I would try a coil of wire if you have a soldering gun. It won’t work with a pencil type soldering gun.
Or, run a jumper off a running GM with HEI, from the tach lead to the tachometer. You just need power, ground and input which was optional on most. It could be a 6 cylinder as it still reads. Unfortunately I don’t live nearby or I could loan my Kent-Moore frequency generator. It has multiple out puts to check VSS input, ABS as seen on scan tool and many other on-off circuits directed by the service manual.
Note; Some digital tachs require a “Pull-up” resistor to B+ and increase signal strength. Just a thought.
Thanks, ive heard of using an old 12 charger as it still has 60 hz onthe dc ……i should have bought a freq gen 30 years ago, lol inever thought id use one again…til next time….thanks
@@skipprice6843 I had to laugh a little when I read the little line of your post in my notification list. I pictured a full sized battery charger weighing 60 lbs. held up near a distributor. LOL!
I am sure a couple of jumper wires connecting your unknown tach onto a running HEI vehicle. Yes, many are coil over or coil near plug, but a tach signal terminal is a simple 1/4 male spade that a female 1/4” terminal will plug into. This would be easiest to do as a factory tach from a vehicle 8 cylinder engine will simply need ground, B+ and input signal. So barrow a signal from uncle Joe. Not the one in the White House! Just a person you know because it can’t hurt or damage anything.
If you remember when they had Sear’s, but Radio Shack sold a spool of meter wire. Red & Black but a package of alligator clips (unless over seas, call crocodile clip) but soft silicone jacket over low oxygen copper wire made great jumper wires. I still have a
4 ft, 8 ft, 12 ft with soldered ends and shrink tubing on ends. I have spool of 3M 5/16” shrink tubing on 50 ft roll on large cardboard sleeve. I said I enjoy electrical. As any wire will do, just buy or make some. If I am testing a fuel pump or tank sending unit voltage drop I need a long jumper to battery. Now I know exactly what voltage is, if I have a good ground (voltage drop) then I see a rusted metal filter, I change it. I drain it in solvent tank, but blow thru it and note plugged or not. Fused jumper (15amp) at relay center as GM had green terminal or pump direct line then place amp clamp over it! 7.5 amps normal. (Tip: head lamp is 4 amps, solder jumpers to plug into vehicle harness. Dim, power or ground problem. Bright, all is good)
But using the primary scope or lab scope shows amperage waveform. If jagged, pump is worn at brushes or commutator plates on armature down to plastic) So if current is low, pump is worn. Current is high, restriction or plugged filter) easy and quick.
nice job!
Thanks!