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 Post subject: total timing under boost
PostPosted: Thu May 08, 2014 10:35 am 
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Turbo Slant 6
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Joined: Fri Jul 13, 2007 11:11 pm
Posts: 794
Location: clearwater florida
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I'm about to pop the dist out a limit the total timing some more just was curious what you guys are running for total timing.

I was planning to weld the slots enough for 18 or 20 total?
The car did well at TnT last night but started falling on its face in 3rd gear pretty sure it's getting into a bit of detonation with the increase in boost since I didn't pick up any mph on the big end. The Duster ran a 8.4 @85 with a 1.9 60ft so still happy with the results despite the hickups in 3rd gear.

Kev

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 Post subject:
PostPosted: Thu May 08, 2014 12:38 pm 
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Turbo Slant 6
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Joined: Fri Apr 27, 2007 5:50 pm
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i saw this thread a while ago. http://www.slantsix.org/forum/viewtopic ... gth#403425 and was under the assumption that the stock mechanical advance was limited to 18*. now i could be and probably am wrong about that.

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 Post subject:
PostPosted: Thu May 08, 2014 6:28 pm 
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Joined: Mon Oct 21, 2002 11:08 am
Posts: 16505
Location: Blacksburg, VA
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I have not gone much above 18 deg total on my Dart under boost. I have been pretty conservative since I have been driving/racing the car to/on both coasts with no breakage. I've been using around 14-18 deg total and have not seen big differences in power although other factors are at play.

Junior, 15-30 deg is the spread between initial and final mechanical advance on stock dists. You want to narrow the spread to maybe 8 deg so you can have 10 deg at idle and 18 deg at full boost.

Lou

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 Post subject:
PostPosted: Thu May 08, 2014 10:43 pm 
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Turbo Slant 6
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Joined: Fri Jul 13, 2007 11:11 pm
Posts: 794
Location: clearwater florida
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I think I'm getting confused according to those slot length measurement say .380 for 18 degree would mean the dist advances another 18 + your initial right? I took my dist out today and measured my slots they are at .300 from when I welded it years ago before I knew anything about the slot length measurements lol. So where does that put me Lou? If my timing is 10 degree initial is my dist only advancing like 6 or 8 degrees of mechanical which would put me around 16 to 18 total timing? Or am I thinking about this wrong? My slot almost looks like a square lol it looks like almost no room for the weights to even slide.

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 Post subject:
PostPosted: Fri May 09, 2014 12:10 am 
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Turbo Slant 6
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Joined: Fri Apr 27, 2007 5:50 pm
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lol love this site. just had an ah ha moment. completely forgot about the initial timing. thanks Lou, you probably just saved me from having to use my spare motor.

so just to clear this up real quick i need to limit the movement to somewhere in the .300-.310 range to get 18 degrees total with 10 base? does that sound about right? doing the math it seems to break down to .015-.017 per degree total. what do you use to shorten the slots? in the link it says to use the heavy spring. i dont know if i like that idea.

these are my figures
3 degree 6 degree 0.290
4 degree 8 degree 0.307
5 degree 10 degree 0.325

these are from the thread previously listed.
6 degree 12 degree 0.340
7 degree 14 degree 0.357
8 degree 16 degree 0.375
9 degree 18 degree 0.390



sorry to hijack your thread Kev.


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 Post subject:
PostPosted: Fri May 09, 2014 6:06 am 
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Joined: Mon Oct 21, 2002 11:08 am
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Location: Blacksburg, VA
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I have never measured the length of a slot (weld then eyeball then test in car), but those numbers sound about right. Yes, it should barely move (maybe 0.060-0.090" movement of the pin) for 8 deg advance "spread".

DusterIdiot is the real expert on the particular measurements here.

Lou

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 Post subject:
PostPosted: Fri May 09, 2014 8:08 am 
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Turbo EFI
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Joined: Wed Sep 20, 2006 7:08 pm
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Location: The Hand
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Just put the race weight dist springs in and set total timing with the vac line off at 18 or 19 degrees. Plug the vac line back on......done.

Normal driving will see additional advance from the vacuum advance and under boost it will be limited to what you set from above.

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 Post subject:
PostPosted: Sat May 10, 2014 1:57 am 
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Supercharged

Joined: Thu May 12, 2005 11:50 pm
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Location: So California
Car Model: 64 Plymouth Valiant
You can wrap some wire on the outside of the slot to shorten the hole.

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 Post subject:
PostPosted: Sun May 11, 2014 11:02 pm 
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Turbo Slant 6
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Joined: Sat Feb 06, 2010 10:21 pm
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I run 18 degrees total with a locked plate and no vacuum advance diaphragm. It starts easily, (no kickback) and idles nicely; the cruise experience is smooth and using 10 pounds of boost it feels really good.

I don't understand why it doesn't seem to need any kind of a curve, but I'll take it... :)

Bill in Conway, Arkansas

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