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  #1  
Old 06-05-2005, 03:29 PM
71SATELITE 71SATELITE is offline
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Default Another advance question!!

Here it is, the first question might answer the rest. Do MP performance distributors come with the light weight springs (quick advance) installed? I thought they did but I have been wrong before. Here is my advance trouble, car is a primarliy stock 71 318, automatic, 271 gears, 14 inch rims, stock cam, stock 2bl, and I never noticed this problem until I installed my new ignition; however, I don't think the ignition is the root of all evil it is just amplifiying a pre exsiting problem. Car starts better than ever, runs good down low until advance needs to kick in and then it surges like power... gurgle... power... gurgle like the the advance is in and out until reaching about 2k and then everything is once again great, haveing ten times more power and pick up then prior to the new ignition. It seems like the light throttle is killing it. I watched it with a timing light the other day to see how the curve came in to see if it was to slow or two fast. Everything was good until 1200 then the mark was so eratic I couldn't see it with the light. Around 1700 it was back just fine. I tried this with the vac advance attached and un attached with the same results. The total advace and rate was really weak which leads me to belive that the motor wants to rev up but the advance is holding it back making it sputter. The distibutor is two years old with accell cut to fit wires. Any ideas?
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  #2  
Old 06-05-2005, 07:04 PM
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ehostler ehostler is offline
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IF your distributor has the adjustable vacuum advance, then it also has the light springs (I've seen a few MOPAR performance kits that did not have the adjustable vacuum and they did not have the light springs).

For watching the advance curve, you will need to remove the Jacobs from the circuit. Run it straight with jsut the MOPAR ECU. Things start to get erratic because of the multi spark. The timing light throws light, every time it senses spark.

Once you get the jacobs out of the picture, you will be able to see what the MOPAR ECU is doing and what the distributor timing is doing.
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Old 06-05-2005, 08:53 PM
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Stock 318 with 271 gears, and a 71 satelite(from your login).

It could be that you are getting your advance in way too soon. I have noticed that the mp dist fcomes with really light springs, and the slot left almost wide open.

The slot lengthe is adjustable, and tighter springs need to be used.

What you are describing sounds like the advance is coming on too soon. It detonates, regains it composure, and trys again.

With those gears,and that heavy car, you're total mechanical advance shouldn't be in before 3000 rpm. Even a little later would be ok.

The weights on the mp dist are smaller than the stock ones. I'd put the lighter stock spring(from your old dist) on to the mp one and see what happens. It will probably solve most of your trouble.
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Old 06-05-2005, 09:44 PM
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Quote:
Originally Posted by ehostler
IF your distributor has the adjustable vacuum advance, then it also has the light springs (I've seen a few MOPAR performance kits that did not have the adjustable vacuum and they did not have the light springs).

For watching the advance curve, you will need to remove the Jacobs from the circuit. Run it straight with jsut the MOPAR ECU. Things start to get erratic because of the multi spark. The timing light throws light, every time it senses spark.

Once you get the jacobs out of the picture, you will be able to see what the MOPAR ECU is doing and what the distributor timing is doing.
I don't think Jacobs is a multispark. Are you sure?

torch
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Old 06-05-2005, 10:16 PM
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Yes, the Jacobs system is a multi-spark system with capacitive discharge. They always have been. Now that Mr. Gasket owns them, it is possible (doubtful) that they have removed the multispark abilities.

MSD is a programmed multispark setup. At x RPM, you get y sparks per ignition event.

Jacob's is a reactive multispark. It fires off a hot initial spark. It then measures the electrical differential and determines how well the fuel was burnt. It will then follw up with a programmed number of sparks to complete the fuel burn. It does this for every ignition event.

Once you get to about 3,000 - 3,500 RPM, both boxs stop multi spark and just go to hot sparks. This is due to the short ignition window.
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Old 06-05-2005, 10:17 PM
71SATELITE 71SATELITE is offline
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The only really odd thing is how apparent it is with the new helper ignition system. It feels more like a V8 now for sure and cruises and starts better. Before is was all right but never really showed any symptoms like this but before it wouldn't really get out of its own way very well. I am once again in a different school away from the house so I will check out everything this weekend. E I was wrapping my brain around what you said and it makes perfect sense about the whole multi spark thing. It worked good with my timing light until about 12-15 K and just went nuts, couldn't track it and I have a pretty sexy timing light. My distributor has the adjustable vac so hopefully it has the light springs. I re connected my vac advance after I initially posted this and drove my kids to the pool and it a world a difference having the vac advance attached compared to the straight mech advance. It was a lot better. Any more thoghts on this one anybody?
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  #7  
Old 06-05-2005, 11:41 PM
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E, I think we're both right. I looked around, and it seems that the FC1000 and the I.C.E. Pack ignitions are multispark, and the Pro Street and Mileage Master units are not. It seems they are all capacitive discharge. The first two systems are new to me, since it's been a while since I've looked at Jacobs' stuff.

torch
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Old 06-06-2005, 12:11 AM
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OK, the original Jacobs was multi spark. I guess the newer Jacobs uses a variable duration spark. Once electrical differential reaches a certain point, it breaks the spark.
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Old 06-06-2005, 04:12 AM
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Quote:
Originally Posted by cutting torch
E, I think we're both right. I looked around, and it seems that the FC1000 and the I.C.E. Pack ignitions are multispark, and the Pro Street and Mileage Master units are not. It seems they are all capacitive discharge. The first two systems are new to me, since it's been a while since I've looked at Jacobs' stuff.

torch
Err ..... Not quite right ! - Have a look at http://go.mrgasket.com/pdf/74069G_jacobs.pdf
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Old 06-06-2005, 06:56 AM
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The site I found showed the old style Pro street and milage master units that were single spark. I didn't know those had been updated to multispark, so I stand corrected. My bad! Thanks for the link.

torch
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