Reluctor and Phasing....

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JoeSBP

JoeSBP

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Gentleman, I know the CW/CCW discussion between the SB/BB has been beaten to death, so I apologize up front for starting this thread.

After searching the forum, it is very obvious that a SB distributor has a clockwise(CW) rotation while a BB uses a counter-clockwise(CCW) rotation. I am running one of the aftermarket distributors that is obviously a stock knockoff. When looking at pics on the forum, its clear that the OEM reluctor had an arrow marking rotation to properly index the reluctor on the shaft via the roll pin. My question is, can someone please tell me the position of the reluctor fins in relation to the roll pin for a SB. One side has the roll pin in line with a fin, the other side has the rollpin offset to the right of a fin. I'm thinking our Chinese friends incorrectly marked this reluctor
 
Some distributors have two roll pin slots and for small block you want the one opposite the rotor slot in the top of the shaft and the two lines opposite the rotor slot.
I'll try and find a reference if yours doesn't have those marks and post it.

This is the way they go on marked OEM small block distributors.
Sorry again about posting the wrong distributor earlier.

image_84.jpg
 
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I was dealing with this just the other day as well.
Lining up the pickup coil with a reluctor-line made the rotor end up somewhere right between two cable terminals on the cap.
Not sure what I want to do here yet.
I could file another alignment gap in the distributor cap so it all lines up better, but that would be 'forgottten' to do again is the cap ever got replaced ofcourse.
Changing/altering the reluctor should be preferred me thinks.
 
The super cool reluctors are machined with multiple slots and you degree them.

That's what I'd find, if it was me
 
BigBlockMopar said:
I was dealing with this just the other day as well.
Lining up the pickup coil with a reluctor-line made the rotor end up somewhere right between two cable terminals on the cap.
Not sure what I want to do here yet.
I could file another alignment gap in the distributor cap so it all lines up better, but that would be 'forgottten' to do again is the cap ever got replaced ofcourse.
Changing/altering the reluctor should be preferred me thinks.
Click to expand...

If I remember correctly the trigger event is just slightly after the two are lined up. (trailing edge on the pickup coil)
Could this explain it?
Also if the distributor pickup wires are swapped it will throw the phasing way off.
Ran across that just a little bit ago with a member having issue's with timing jumping all over the place and his total timing going too high.
 
I am a Moper guy from way back, but I worked for Cadillac for 10 years and GM for 20 years for the technology, sorry way better than Mopars. I suggest looking up distributor-less ignition, how it works. The engineers at Mopar are not stupid, they would not make a distributor that would fire 2 cyls at once or even close. If you look at the reluctor and the rotor it looks like it could fire ether cyl as it is between posts. The thing is that it will only fire the cyl that has the less resistance to ground, fuel in the chamber and under high pressure. This it why some say to keep cyl 5 and 7 plug wires at least 1" apart at all times as they are 90 deg from firing from each other. Other than that there is no possibility of crossfire unless you have a bad cap.
 
Most important when the reluctor and the pick up are lined up and the rotor is in between 2 post the rotation of the rotor should be cumming up on the cyl to be fired not away from it.
 
So you are saying that a SB can't technically crossfire. Although you might not get an actual firing event in that (wrong)cylinder, that (wrong)plug will be sparking, pulling spark away from the (intended)cylinder right?
 
Wrong, If you read the technology on distributor less ignition you have 1 coil and 2 plugs
even that one fires on the exhaust and one fires on compression the spark will only travel to the ground with the less resistance, never to both.
 
The arrow is for big block and small block, they go in different directions.
 
Looking at the design of the stock rotor, it would actually be very easy to build an adjustable one. Cut the top of the rotor off, maintaining the center stem with key. Use a nylon bushing with the same ID as the rotor center OD. Super glue the rotor top to the bushing. Drill/tap the bushing so a nylon screw can work as a jam. Mark #1 on distributor body, rotate engine so it's at desired initial. Turn rotor to trail edge of #1 and tighten jam. Once you run/test with a skeletonized cap you could super glue rotor together fully...
 
brian6pac said:
Wrong, If you read the technology on distributor less ignition you have 1 coil and 2 plugs
even that one fires on the exhaust and one fires on compression the spark will only travel to the ground with the less resistance, never to both.
Click to expand...

I'm talking about spark scatter on a regular distributor. I'm not really sure what you are talking about
 
What about shimming the vacuum canister? That could add timing without changing the relationship of the rotor/cap tower
 
yes, pic 2 has the small block pinned at the counterclockwise arrow, and the small block distrib. rotates clockwise!
 
So the pic is correct, or the reluctor is installed the the BB position?
 
You are way out of control on this, find a factory service manual on a 1986 Dodge Shelby 2.2 turbo and read about the ignition system. Back then they could retard the timing on each individual cyl independently at any rpm for preignition. The spark is fired at the time the reluctor and the pickup are lined up. The electricity (spark) is so fast the rotor has no time to turn.
 
What do you mean I'm way out of control? The initial timing is set by rotating the distributor housing, altering the alignment of the pickup/reluctor. The mechanical advance works by also alternating the alignment of the pickup/reluctor. Both of these also directly effect the alignment of the rotor to the cap tower. The whole point is to ensure the rotor is adequately aligned with the correct cap tower for the full sweep between initial and total. Vacuum advance isn't a factor because it does not alter the alignment of the rotor/cap tower.

I am not concerned with any distributorless ignition or multi plug setup because that is not what I have.
 
You are correct about the alignment of the reluctor and the pick up coil and that is what controls timing. They have not so much effect on rotor and cap as spark will jump. like I said educate yourself, look up facts.
 
But isn't that the whole point? To ensure the spark has the shortest jump possible for the full timing sweep? Not a short jump at initial, and long jump at total, etc
 
AH hell, you guys are right about that picture being a big block distributor.
I posted the wrong one, but I'm positive I have the small block pic here somewhere.

Please excuse that stupid mistake.

There, I replaced that pic up at the top with the right picture.
 
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Well I wanted to say, much ado about nothing, cuz it sounds cool.
The fact is that the further that spark has to jump inside the cap, the better! Just so long as it does in fact jump, and so long as it jumps to the right tower,and that as the revs climb and the advance mech is brought into play, everything continues this way.
The bigger the gap,the more energy will be delivered to the plug. That's the way the coil works. So really who cares exactly where the rotor tip is. I wasted so much time dialing this in and it made exactly zero difference in my streeter.Just make sure the coil is up to the task. I have the big square-top Accel SuperCoil. It has no problem hitting 7200. And it idles around all summer's day in 95* temps.Keep a spare hi-quality rotor, in case you burn off the rotor tip. ZZZZZZZZZZZZZZZ
 
Seems like a final test would be to spin the distributor by hand w/ the cap off and shine a timing light at it to insure the reluctor aligns with the pickup when it flashes. For this, clip the coil HV wire to the engine block and clamp the timing light over it. You can find an MSD video on that, or search for the Crane Cams XR700 manual, see "rotor phasing". Can also cut a hole in an old distributor cap to shine the light as the engine is running to assure the rotor tip aligns w/ the post. It will move back and forth as vacuum advance changes, but not w/ rpm.
 
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