MP Dizzy?

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Cuda416

Cuda416

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Looking through my pile of random parts I might have found a MP small block dizzy. Tag says 3690431. It appears to be a "left hand unit" which is confusing to me but hey, what isn't these days.

Looking at the governor plate and measuring for "good measure", it has a total mech adv of 24 deg. Looks like someone already futzed with the springs, only one inside...

Anything special? Thinking of using this instead of the other one with 30 deg total we have.

20210116_183102.jpg


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Cuda416 said:
Looking through my pile of random parts I might have found a MP small block dizzy. Tag says 3690431. It appears to be a "left hand unit" which is confusing to me but hey, what isn't these days.

Looking at the governor plate and measuring for "good measure", it has a total mech adv of 24 deg. Looks like someone already futzed with the springs, only one inside...

Anything special? Thinking of using this instead of the other one with 30 deg total we have.

View attachment 1715671621

View attachment 1715671622
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For the B engine.
 
halifaxhops said:
Basically a fast advance in them from MP.
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Exactly right. That's all they were. A stock Mopar electronic unit with a set of springs. People don't realize how good the stock units were. The advance kit was all they needed to be an HP unit. Yet people run them down and talk about how "great" MSD is. BAH humbug.
 
RustyRatRod said:
Exactly right. That's all they were. A stock Mopar electronic unit with a set of springs. People don't realize how good the stock units were. The advance kit was all they needed to be an HP unit. Yet people run them down and talk about how "great" MSD is. BAH humbug.
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Hey Rusty I remember people saying if I remember correctly that those units added too much advance for a setup that needed let's say over 10° initial without modification ? Just for a side note I run Mopar performance distributors and control units am a fan.
 
Okay looking back on the original post I see he believes the advanced to be 24°you could work with that.
 
K.O. SWINGER said:
Hey Rusty I remember people saying if I remember correctly that those units added too much advance for a setup that needed let's say over 10° initial without modification ? Just for a side note I run Mopar performance distributors and control units am a fan.
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If you put initial where it really needs to be for performance, all of them really have too much total, unless you limit them somehow.
 
RustyRatRod said:
If you put initial where it really needs to be for performance, all of them really have too much total, unless you limit them somehow.
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What are some good number for initial and total? When does it become a requirement to start limiting mech advance? I suppose what I am asking is does it even help on an otherwise "stock" engine such as a 5.9 truck motor with a carb an no other mods?
 
Cuda416 said:
What are some good number for initial and total? When does it become a requirement to start limiting mech advance? I suppose what I am asking is does it even help on an otherwise "stock" engine such as a 5.9 truck motor with a carb an no other mods?
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Hell yeah it'll help. I would "start" at 15 initial and see how it does. The Magnums have a shorter deck height and higher compression than their LA counterparts, so you might get into detonation before the LA would. Even the stock engine would still benefit from the FBO limiter plate. I would keep total to 36 "at the most" all in by 3000 in a heavy truck.
 
Most of them came with a 15 degree advance cam (30 at the crank) and light springs usually all in by 12-1500.
 
RustyRatRod said:
Hell yeah it'll help. I would "start" at 15 initial and see how it does. The Magnums have a shorter deck height and higher compression than their LA counterparts, so you might get into detonation before the LA would. Even the stock engine would still benefit from the FBO limiter plate. I would keep total to 36 "at the most" all in by 3000 in a heavy truck.
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Thanks, to be clear, this truck motor is in a 65 valiant. We've been having trouble getting things tuned between the carb and dist. Current dist has 30 mechanical which I am going to limit this week by welding up the slots (centermost edge). I'm going to shoot for 20 total mech (0.405 ish) slots, then try again.
 
halifaxhops said:
Most of them came with a 15 degree advance cam (30 at the crank) and light springs usually all in by 12-1500.
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Are you talking about stock? That's what are current one does right now and it's a nightmare. We can get it to idle "OK", 20 inches of Hg, but when get on it, no matter what we do, it craps itself. I was thinking our dist is the problem and a good place to start.
 
No the MP ones they are all pretty much the same curve, let me find a chart. @Mattax definately has them
 
Cuda416 said:
Thanks, to be clear, this truck motor is in a 65 valiant. We've been having trouble getting things tuned between the carb and dist. Current dist has 30 mechanical which I am going to limit this week by welding up the slots (centermost edge). I'm going to shoot for 20 total mech (0.405 ish) slots, then try again.
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**** man, you can certainly do it that way, but those limiter plates are really nice and adjustable.
 
Like Rob said great for the strip, the street not so much. Hope it helps.
 
RustyRatRod said:
**** man, you can certainly do it that way, but those limiter plates are really nice and adjustable.
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Yes they are and nothing wrong with them. Only "problem" I'd heard of is a little noise after install. Not a show stopper and I'm not agenst them but I'm that guy who has to beat his head against the engine for a bit. This is my sons car and he'll most likely end up getting a "better" dist later. Not entirely sure what that means yet :)
 
halifaxhops said:
Like Rob said great for the strip, the street not so much. Hope it helps.
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yessir, loads. I appreciate it. The dist we have actually came from your generosity a while back. Came out of your core pile. Thanks again for that. Functionally, it's been great.
 
RustyRatRod said:
Exactly right. That's all they were. A stock Mopar electronic unit with a set of springs. People don't realize how good the stock units were. The advance kit was all they needed to be an HP unit. Yet people run them down and talk about how "great" MSD is. BAH humbug.
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Wrong! They only removed the big spring in it. Small spring is the factory one as any other dist. That is a street dist that came in their conversion kit to change from points or a lean burn. Kim
 
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