Adjusting reluctor gap with vac advance problem
#1365769
01/07/13 05:18 AM
01/07/13 05:18 AM
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Oregon
hooziewhatsit
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A while back I did a normal MP electronic ignition swap on the 318 in my work truck. Shortly after I got a mity-vac and pulled the (brand new) distributor so I could adjust the reluctor gap on the bench and do it right. Long story short, to have 0.008" clearance with the vacuum advance engaged, I have ~0.020" clearance with no advance. If I have 0.008" without the vac advance, then the reluctor collides with the pickup when the advance kicks in.  It's been running in the summer with 0.020" gap seemingly just fine. There's also a couple thou difference depending on where the roll pin is on the reluctor. It sits slightly off-center. It looked like the pivot point was pretty well fixed which would make it hard to true up. Is there any way to get it closer to 0.008" throughout its travel? Also, can I just file down on some of the reluctor teeth to make them uniform length? Now that it's cold out, I'm having a hard start issue. But I'm not sure if it's related to the gap being too big, or to IGN1 not having power during crank (ECU gets ~7.5v backfed from the BR). If I jump +12v to the ECU, it starts right up. But that may be a separate issue 
If you ever find yourself in a fair fight, your tactics suck.
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Re: Adjusting reluctor gap with vac advance problem
[Re: hooziewhatsit]
#1365770
01/07/13 10:08 AM
01/07/13 10:08 AM
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Posts: 6,095
Valencia, España
NachoRT74
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tipically.
by geometric is nearly imposible to keep the gap the same allong his travel. Pickup and reluctor, get both diff circunference radious.
what I have done with success is bend the pickup coil bracket back and forth, here and there, until get the best gap relation in both positions. Made to get 7-8 gap without vacuum and maybe 9-10 with full vacuum. Thats was with factory vacuum setup, which gets A LOT OF ADVANCE ( maybe up to 10 degrees )... then shortened the vacuum advance to maybe just 4 or 6 degrees.
needs patiente for that... is a tryal and error process.
Sometimes the vacuum pivot and pickup coil bracket assembly gets lots of play due the vacuum stud and hole on bracket doesn't match perfect. I have filled it with teflon tape over the vacuum stud.
With a Charger born in Chrysler assembly plant in Valencia, Venezuela
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Re: Adjusting reluctor gap with vac advance problem
[Re: RapidRobert]
#1365772
01/07/13 03:29 PM
01/07/13 03:29 PM
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Valencia, España
NachoRT74
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need to note that you need to be sure all reluctor points are set at same height too
With a Charger born in Chrysler assembly plant in Valencia, Venezuela
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Re: Adjusting reluctor gap with vac advance problem
[Re: hooziewhatsit]
#1365777
01/20/13 03:14 AM
01/20/13 03:14 AM
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hooziewhatsit
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It finally warmed up and got nice today (hit 32*F  ), so I took another look at it. I have a couple problems: 1 - The reluctor teeth. Measuring from the ID (where the reluctor touches the shaft) to the outer edge of each tooth, there is a ~0.005" difference from the shortest to tallest tooth. This is noticeable when looking at the gap and spinning the shaft. 2 - I did a few things to the entire pickup mechanism, and got it to have 0.008" difference between vac and (0.016") with no vacuum. The big gap with no advance is definitely the issue. It's currently gapped to 0.008 +5 slop, and it fires up cold GREAT. But, I don't have vacuum advance. Quote:
what I have done with success is bend the pickup coil bracket back and forth, here and there, until get the best gap relation in both positions.
Nacho, are you referring to adjusting the bracket that the two wires go to?
Edit: Just drew a picture and figured out 90% of the problem with #2. Will try to verify it tomorrow. #1 is still a problem though.
If you ever find yourself in a fair fight, your tactics suck.
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Re: Adjusting reluctor gap with vac advance problem
[Re: hooziewhatsit]
#1365779
01/20/13 12:39 PM
01/20/13 12:39 PM
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Joined: Aug 2007
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Valencia, España
NachoRT74
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Quote:
Quote:
what I have done with success is bend the pickup coil bracket back and forth, here and there, until get the best gap relation in both positions.
Nacho, are you referring to adjusting the bracket that the two wires go to?
that OR the bottom section where magnet is. As I told you is a tryal an error method.
If you find can remove the coil from bracket and reinstall it without problem ( usually is posible ) you can work there, removing the coil to save from damage on it.
talking about tooth height. You must consider the reluctor can get a small difference mounted on shaft due the pin is pushing out one side of reluctor. I adjust the tooth height MOUNTED, using a fine file, setting the height against the pickup ( no matter how much is the gap at this moment )
With a Charger born in Chrysler assembly plant in Valencia, Venezuela
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Re: Adjusting reluctor gap with vac advance problem
[Re: NachoRT74]
#1365780
01/20/13 08:17 PM
01/20/13 08:17 PM
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Oregon
hooziewhatsit
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 10-12 clearance on all teeth, with and without the vac advance engaged. Later tonight I can make a picture, but the short version is that you have to shorten and/or lengthen the arm for the vacuum advance to get more uniform gaps as the advance engages. A drawing really helps show how this works. I also clamped a file to a board and adjusted the height of the reluctor teeth. It does seem to idle better already, so I wonder if that was the cause of my rough idle when it was cold.
If you ever find yourself in a fair fight, your tactics suck.
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Re: Adjusting reluctor gap with vac advance problem
[Re: hooziewhatsit]
#1365781
01/21/13 01:16 AM
01/21/13 01:16 AM
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hooziewhatsit
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Let's see if this makes any sense. Like Nacho mentioned, the reluctor and the pickup travel on different curves because their diameters are different. Like the picture shows, this puts the pickup a varying distance from the reluctor, depending on the length of the vacuum advance arm. Initially, my arm was too long, which is why the gap got a lot smaller when the advance was applied. The only thing that changes this is the length of the arm going to the vacuum advance can. I tweaked the Z portion of the arm to make it ~0.050" shorter. This put the pickups' travel over B, rather than A->B. This is mostly trial and error until you find the sweet spot. Some distributors have an alignment pin to keep the vac advance can in one spot. Mine didn't, which allowed a little bit of adjustment, but it still wasn't enough.
If you ever find yourself in a fair fight, your tactics suck.
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Re: Adjusting reluctor gap with vac advance problem
[Re: hooziewhatsit]
#1365782
01/21/13 01:26 AM
01/21/13 01:26 AM
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Today? Who Knows?
1_WILD_RT
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Which is why Ford & GM pivot their breaker plate on the same center as the shaft... But Chrysler had the best engineers...  I love my old Mopars but some of the stuff they did really sucked...
"The Armies of our ancestors were lucky, in that they were not trailed by a second army of pencil pushers."
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Re: Adjusting reluctor gap with vac advance problem
[Re: hooziewhatsit]
#1365783
01/21/13 01:59 AM
01/21/13 01:59 AM
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Joined: Aug 2007
Posts: 6,095
Valencia, España
NachoRT74
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Interesting method HOWEVER I think bending the vacuum advance link, will affect the phasing IMHO
With a Charger born in Chrysler assembly plant in Valencia, Venezuela
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I'd have to check again, but I think mine is otherwise fine, it's just not centered on the shaft properly. The side with the roll pin sticks a couple thousandths farther out. Just enough to be annoying.
