discussion on ignition pick up coils

-
I believe that the pick up is the same. You are correct that SB/BB turn in different directions. SB turns clockwise, the pick up wheel has two grooves in it, one is located for corresponding direction.
 
What I was allway told in the past is that SB had a orange and black wire and where wound in one direction, the BB had a gray and black wire and was wound in the opposite direction. You could not interchange them because they would not run right.

Read BEWY post # 9 in the link above
 
Last edited:
There's no reason why they cannot be the same. Ma could have easily engineered them "same." My recollection is that they are the same. You should know, right? That the reluctor is the same but is installed differently. There are two roll pin slots, 1 for CW and 1 for CCW
 
My eyes are open, my small blocks dist is grey/black wires. I am having issues with splugs. Too rich, oil fouled, sounds like now and then a popping miss. But it runs pretty good up to 5000. So, I tried to answer a question, and now I have questions!
 
brian6pac said:
Need some input on Ignition pick-up coils BB vs SB are they different ?
I say yes but it seems part manufactures are listing both the same.
They can't be the same because of the different rotation of the dist.


WAI DST3890 Distributor (And Other Chinese Variants)
Click to expand...
There had to be a reason why originally the small block coil wires were org/blk and big blocks gry/blk like you have mentioned but perhaps it was just over engineering by Chrysler at the time for whatever reason. And with the aftermarket maybe the engineers saw a way to wire them to work on both? Just a wild guess, no clue, but what I have has worked as it should on quite a few older SB Mopars.
 
CRUZE 418 said:
My eyes are open, my small blocks dist is grey/black wires. I am having issues with splugs. Too rich, oil fouled, sounds like now and then a popping miss. But it runs pretty good up to 5000. So, I tried to answer a question, and now I have questions!
Click to expand...

Maybe you could make a jumper to cross the wires and see if it fixes the problems.

Like I said in the other post I had a drivability problem and problem setting the timing, marks jumping all over the place. After the change car ran great and timing marks where rock solid, no jumping around at all.
 
I was going to tear my new engine down and re ring it. After a leak down test, decided against that. I may have several issues, I thought it was the six-pack and trying to get it right. Now I don't know. Going to take the whole FBO set up out and put my chrome module, coil and ballast back in in. Confused by an oil fouled #1 plug, and the cyl leaked at 3%. Going to reseal the intake gaskets first, then try the ign.
It's just too much to put down on paper, so I haven't asked for help. New 418 engine. My timing seems pretty stable at 20°.
 
Pickup sensors generate voltage based on rate of change of magnetic flux. Pickup coil is biased with a rectangular magnet on back side. When reluctor rotates, area between teeth is distant to pickup, with space consistent, so little change in flux, sensor output near zero. As tooth approaches pickup, flux reduces, and sensor output goes negative, when at center of tooth, output drops to zero, as tooth exits, positive signal, followed by zero again in open space between teeth. Rotation CW vs CCW, results in same look of signal, difference is in edge of tooth. Ignition trigger is always on trailing edge. No rotation, no signal, faster rotation signal amplitude proportional to RPM.

As others suggest, relutor set for edge difference, changing rotor phase for sb and bb.

An easy way to check is use a timing light, set desired timing. An example is 13 BTDC at idle. Turn off engine, turn crank to 13 BTDC, pull distributor cap, observe reluctor tooth to pickup nub location, it should be on trailing edge, based on rotation. Remember what that looks like, use it to static time, and be within 1 to 2 degrees. It is important to rotate correctly to position, and never back it up, backlash will mess up test.
 
Last edited:
brian6pac said:
Maybe you could make a jumper to cross the wires and see if it fixes the problems.

Like I said in the other post I had a drivability problem and problem setting the timing, marks jumping all over the place. After the change car ran great and timing marks where rock solid, no jumping around at all.
Click to expand...

What he needs to check for is "rotor phasing" Google that. Couple videos and other hits
 
OK LA. B and RB are usually red/black Slant white/black. from mopar. Grey black are usually aftermarket or MP. The pick ups pretty much are all the same the plate they mount on are sometimes different. It is the reluctor clocking that really make the phasing on them from what I have seen.
 
Oh yeah there is a magnet on the coil I will check and see if the polarity is different between the orange and gray pickups,
 
MOPAR and GM ignition trigger correctly when pickup signal goes positive, after first going negative. Both trigger on trailing edge, that is important! Trailing edge is more repeatable... and phased correctly with rotor based on configuration for particular rotation.

I have used scope to look at trigger event vs polarity, but for many, post #9 is good test.
 
KitCarlson said:
Visual observation suggest GM pickup coil assembly is offset! MOPAR offsets reluctor.
Click to expand...
Thanks Kit!
Unfortunately there remains the possibility with poorly made products that the wire leads get mixed up.
 
Yes, when polarity is off (magnet, or wire), it will trigger on leading tooth edge, and be AFU. Then if rotor is phased with that, then FUBAR. Trigger must happen trailing, on positive edge after going zero, from negative peak
 
IMG_20210510_111128.jpg

Sorry for poor sketch. Reverse polarity triggers will vary, they happen in poor position. Correct trigger happens at a more predictable slope. As RPM increases, slope approaches vertical.
 
I looked at the magnetic polarity with a compass and they all seem to be the same, orange, gray, and I have one with 2 black wires.
 
brian6pac said:
I looked at the magnetic polarity with a compass and they all seem to be the same, orange, gray, and I have one with 2 black wires.
Click to expand...
Has to be a aftermarket one I have gotten some in like that also.
 
You must log in or register to reply here.
-

Back
Top