Need help with electronic ignition conversion

[Beck]

I am going to try to convert an old points distributor to electronic. Below is a rough sketch of a Mopar reluctor.

I am trying to figure out what the arrows and lines on it are for. Do the small block and big block Mopar distributors turn in opposite directions? The 2 slots in the base of the reluctor are not 180* apart. I expect one slot is small block and the other is big block locations. There is a pin that goes into these slots, locating it on the shaft.

Now a bigger question, what are the lines for on both sides of the clockwise arrow (top of drawing)? Are they to get the rotor phased correctly in the cap? Are they showing where the non-advanced and full advanced center of the rotor is?

[Beck]

I didn't get very far into this project before I hit a snag. On the Chevy V8 distributors the centrifigal advance is mounted on top of the points plate. On my distributor the advance is mounted below the points plate. If I press the Mopar reluctor onto my shaft I can't get anything back together. The reluctor is to big to install the advance cam retainer and to big to go through the points plate hole.

It's time to back up and regroup. Some things that appear easy aren't.

[chimp koose]

I think the conversion was using a ford reluctor wheel . I don't know what difference that might make , but that is how I understood the conversion

[chimp koose]

If I remember correctly , the breaker cam on the chevy was machined down to press fit the ford reluctor wheel onto it.

[Beck]

I was looking at the Bubbas site from Glen's previous distributor thread. Bubbas uses the Mopar reluctor. Others may use the Ford, but I am not familiar with those swaps.

http://www.lindertech.com/bhrs/chev_8_dist_elec_conv.htm

[wayne petty]

looks like they bored the heck out of the middle of the reluctor..

the mopar reluctors do have 2 slots.. one for small block direction and one for big block direction..   or the pickup coil/reluctor phasing won't match the direction the rotor is pointing..

please when you are doing this.. order up a CLEAR distributor cap from some place like JC Whitney... even if it means getting on their mailing list..  if that still exists.

let me explain some tests you will need to PROVE your set up works properly on the bench .. before you get it in the car and get stuck someplace..


reluctors are made of a sintered material that has weird properties.  it will retain some magnetic field when its been exposed to it..

as the reluctor rotates inside the pickup coil..  it picks up some of the magnetic field.  as the pole pieces of the reluctor approach the pole pieces of the pickup coil.. it starts to generate a small positive electrical signal voltage..  as the pole pieces align. the voltage drops to zero.  as the pole pieces move apart the voltage continues to drop and go negative..  as the pairs start to approach the voltage starts to rise again

this creates an AC voltage sine wave..   it needs to create a voltage over 0.8  volts AC over 0.9 volts AC is better..

the sine wave goes 4/10s of a volt above zero or more.. and  4/10s of a volt below zero.. this as i understand is RMS but i could be wrong..

why is that important to have more than 0.8 volts AC output from the pickup coil..

the power transistor turns on to send negative to the coil primary at just over 3/10s above ZERO RMS.  if you are not getting enough signal voltage you won't turn on the power transistor and there will be NO saturation of the primary winding in the coil.. if the coil is not saturated.. the opening of the power transistor to stop the flow of electrons to cause the magnetic field to collapse will NOT happen..  so no spark will be created.  or worse.. spark may be created sometimes and not under slightly different conditions. like a slow cranking hot..


notice the angle of the spark during this video..

the 13 tooth distributor gear was installed 180 out.. since the housing is locked and not really adjustable on the vortec..  this puts the rotor almost 14 degrees out of phase.. this is why i would like you to experiment on your work bench.. with a clear distributor cap.  vortecs use a crank sensor.  

sorry to bury you under a mountain of tech..

oh.. i would worry about loosing that much reluctor material.. i don't know how much it will reduce the effective magnetic field..

one of the tests i perform is to check the pickup coils for resistance.. usually  at the 2K ohm setting.. i look for 500 to 1500 ohms.. many GM versions end up around 980 ohms..  before i disconnect i spin the shaft.. if i don't get really close to 1.0 volts AC.. i replace the reluctor.

hard to start mopars get this test first.. saves me hours of head scratching looking for a bad component.

[Beck]

I have the reluctor machined and on the distributor. I only had to cut .039 out of the bore for a press fit. I drilled a couple of new holes into the internal plate to mount the pickup coil. Somewhere along the way I got things out of phase so I had to spin the reluctor a bit on the distributor shaft. I was concerned about it getting loose, but I cannot move it by hand.

I don't think they make a clear cap for my distributor. I was planning to cut a hole in a cap to check phasing.  I have the rotor aligned with the plug pin when the pickup coil is in line with the reluctor tooth.

I wish I knew somone with a distributor machine. That would spin it without mounting it in the motor. I could also check my mechanical advance. This distributor has no vac advance.

[wayne petty]

don't need a distributor machine..  to test the phasing..

a clear distributor cap really helps..

if you cannot find one..  drill some holes in the side and the top of a cleaned used distributor cap.. you only need to see ONE rotor to cap GAP..   so you could in fact cut a rather large hole between the cap terminals on both side of just one tower to allow you a view.

a piece of heater hose with a hose clamp on it shoved over the smooth part of the distributor drive gear..

clamp the housing in a vice... or make your own clamp type housing holder.

cut the back out of an old intake manifold..  or even better .. Clamp an intake manifold to the work bench.. put the distributor in the hole..  and use a stock hold down..  a variable speed power drill with a 3/8 bolt chucked in it with the head held in the heater hose with 2 clamps on the hose to limit the up and down movement of the hex head..  or some other creative way to do it..

this is becoming a cheaper and cheaper fix all the time.

please build your spark plug pack.. so you can hook all the spark plugs to it.. and ground the spark plug rack to the intake manifold..    

i wonder if you wrap the cap openings in sandwich wrap.. if you could fill the cap with some mig welding gas.. to allow you to see the arc better.

[chimp koose]

I must have been mistaken about the ford reluctor as I have been looking for the article and have seen nothing but the one with the dodge reluctor .

[Beck]

I have been working an insane amount of hours at work. I have been doing the little stuff there in my spare time. I don't think they would appreciate me spinning the dizzy, firing the plugs, and a timing light flashing after I dimmed the shop lights where every one else is trying to work. That may be pushing things a little too far. I will have to wait at least a week so I can do the rest at home.

Thanks for the input and ideas guys!

A cordless drill won't spin the distributor fast enough to get the mechanical advance all in will it?