Advance Plate

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Bad Sport

Bad Sport

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Okay, here's the deal. I bought a nice dizzy at the swap meet this past Saturday, and it has a 13* advance plate in it and lighter springs.

NOW, what I want to achieve is somewhere in the neighborhood of 34 maybe 36 all in by 2500 or so.

With that said, do I factor in crank degrees (26) or do I go just by the 13*?

If I went with the 26* I would only be running 8* initial to achieve the 34* total.

OR do I go with the 13* and add to that.

I'm still trying to grasp all of the ins and outs of timing.

I know I need to adjust with the vacuum advance plugged off etc. But after talking with him I'm confused again, it flew just the opposite of what we discuss on here, and what I have always done.
 
13 at the dizzy is 26 at the crank. You need to weld up the slot and file to customize the mechanical limit.
 
Assuming the factory 13 is accurate, that will give you 26* of mechanical advance.
 
You use 26 degrees of advance at the crankshaft. But is it 13 or really 12.5? It sounds like the good Mopar Performance distributor. It is better to time to 35 degrees at 2,500 rpm and let the initial fall where it may. It may be partially advanced at your idle speed. Are you sure TDC is at "0" on your balancer? If not you can "time it by ear" look for RRR's method.
 
I understand it will give me 26* at the crank.

But which number do I use when adding in my initial. 13* or 26*

EXAMPLE:

21 initial +13 mechanical = 34 total

OR:

8 initial + 26 = 34 total


Like I said after talking with the guy he has me rethinking things.
 
66fs said:
You use 26 degrees of advance at the crankshaft. But is it 13 or really 12.5? It sounds like the good Mopar Performance distributor. It is better to time to 35 degrees at 2,500 rpm and let the initial fall where it may. It may be partially advanced at your idle speed. Are you sure TDC is at "0" on your balancer? If not you can "time it by ear" look for RRR's method.
Click to expand...

I agree, and it probably will be with the lighter springs. Hmmm... maybe I'll try the " It is better to time to 35 degrees at 2,500 rpm and let the initial fall where it may".
 
Your throttle reponse will improve when you get the intial bumped up, around 16 to 18*. Try running one heavy and one light spring and keep bumping timing up until it pings. Then backoff 2* What is your compression ratio?
 
mderoy340 said:
Your throttle response will improve when you get the initial bumped up, around 16 to 18*. Try running one heavy and one light spring and keep bumping timing up until it pings. Then back off 2* What is your compression ratio?
Click to expand...

And this is where things go sideways.

IF I ran it that high, and add in the 26* at the crank, does that not put me around 42 to 44.

If so, then the dizzy would have to be limited even more than it is now, as in a 10* plate/slot.
 
Bad Sport said:
I agree, and it probably will be with the lighter springs. Hmmm... maybe I'll try the " It is better to time to 35 degrees at 2,500 rpm and let the initial fall where it may".
Click to expand...

That's the easy way, but if you want 12 intial and 34 total you need to limit the advance plate slots to 22 by closing them up more.

Then after that, if you want to run a vacuum advance you may have to adjust the advance pod so it doesn't ping at lower mid throttle RPM's and run it right off the intake vac port on the carb or the intake itself.

Sometime you even have to limit the vac pod travel.

I have a great article on this if you want it, as it helped me verify things.
It would have to be emailed to you so this site doesn't mess it all up and make it unreadable.
 
"Back in the day" I ran mine for quite awhile with NO springs. It dragged enough "friction" on starting to allow startup, and was "full advance" as soon as it fire.

Only "real" answer is to recurve the thing. It is NOT that hard. You can do it yourself if you are patient, specially if you have another dist. to run in the meantime

This is a pretty good article

http://www.moparmusclemagazine.com/...mopar_electronic_ignition_system/viewall.html

And crackedback or somebody came up with these slot dimensions. Note that "as usual" these are dist. degrees

Dimensions for Mopar distributor slots, in DISTRIBUTOR degrees

Modifying advance slots
degrees / slot size
6.............. .340
7................355
8................375
9................390
10...............405
11.5 ...........420
12...............435
13...............445
14...............460
15...............475
16...............490
17...............505
18...............520
 
Bad Sport said:
And this is where things go sideways.

IF I ran it that high, and add in the 26* at the crank, does that not put me around 42 to 44.

If so, then the dizzy would have to be limited even more than it is now, as in a 10* plate/slot.
Click to expand...

What is your compression ratio?
 
67Dart273 said:
http://www.moparmusclemagazine.com/...mopar_electronic_ignition_system/viewall.html



Dimensions for Mopar distributor slots, in DISTRIBUTOR degrees

Modifying advance slots
degrees / slot size
6.............. .340
7................355
8................375
9................390
10...............405
11.5 ...........420
12...............435
13...............445
14...............460
15...............475
16...............490
17...............505
18...............520
Click to expand...


Yeah, I was just rereading that article that I posted for someone else, thanks. I think I have been confusing myself all along, lol.

And those slot measurements I was just looking for , THANK YOU!!
 
.125 or 1/8 inch of shortened slot will take about 10 degrees out of the mechanical at the crank, so I used a 1/8 rod stock and tacked a peice it into the slot on each side.
 
You spend all the time at WOT, time it using the total method.

If you want decent idle manners and quality, sort out the proper initial timing and tailor mechanical advance to fit.
 
crackedback said:
You spend all the time at WOT, time it using the total method.

If you want decent idle manners and quality, sort out the proper initial timing and tailor mechanical advance to fit.
Click to expand...

Yup, the second option. I guess I got some more work to do, (sigh). :D
 
TrailBeast said:
Do you want to know how it can go sideways into WTH? land now, or after. :D
Click to expand...

Oh no--:banghead: :D


The biggest confusion for me has been the crank degree deal.. Out of all of the threads I have read, I don't recall that being thrown out there. It probably was but I missed it.

I have no idea why, but timing just somehow confuses the bologna out of me, I understand the basics but it's the total picture that gets me.
 
Bad Sport said:
Oh no--:banghead: :D


The biggest confusion for me has been the crank degree deal.. Out of all of the threads I have read, I don't recall that being thrown out there. It probably was but I missed it.

I have no idea why, but timing just somehow confuses the bologna out of me, I understand the basics but it's the total picture that gets me.
Click to expand...

As I mentioned before, I took 125 thou out of the mechanical slots to limit the amount of advance it added to the initial. (for my total) without vacuum advance connected.
Now I had about 14 intial and a mechanical of about 12 with one light spring for the total to come in at around 2500 and I thought "ok i'll have to go back in and grind out some of the slot to add more mechanical timing to end up with somewhere around 32-34 total.

Sounds good so far in theory, right?

I decided to drive it first and use my tried and true "by ear" method and see what happens.
I advanced the distributor till I got pinging at WOT, then backed it off about 2 degrees and it still seemed to run and start great.
Back home again I put the light on it and checked it and it had about 13 initial, full advance came in at about 2500 and total was 26 ???????? WTH?
Any more advance I get preignition at WOT, and I can't tell that the spring change made any difference at all either.

Any more initial and I go over 26 total and get ping.
Any less initial and it brings the total down to far.
At this point I said screw it, sombody is lying here and as long as I don't have WOT ping I going to leave till the new engine goes in.

Totally sideways huh?

I went over it with another trusted member here on the phone and in the end we both kinda threw up our hands and decided if it runs good to ignore the reason why it shouldn't. :)
 
I currently have my slots welded up so that my initial is running at 30-32 degrees with total at 36-38. No pinging and this seems to be where it is happiest and idles best. I forget what the slot measurement is but it aint' much! I think I ended up around .330 or .320.
I've got a couple of advance plates I have been experimenting with.

10.5 compression and a 508/292 cam. 4000 stall and 4.56 gears.
 
Welding up the slots is pretty easy. I re-curved the electronic dizzy on my Duster by welding up the slots and then pulling the original heavy spring and replacing it with a light one, leaving the original "light" spring in there (although its now the heavier of the two).

With my Lunati 60404 I'm running 22* advance at idle and 36* all in, mechanical advance only. The slots were welded up and filed to 7* (.355), so I end up with

22 initial + 14 crank = 36* total

IMG_1417_zps89fc3893.jpg


IMG_1422_zps4ba7b85d.jpg
 
OK, I'm going to weld the slots to 9* to give me 18* at the crank and 18* initial. Shooting for 36* all in by 2500rpm.

One original light spring and a lighter spring.

Sound logical?

Also, does anyone recall which direction the allen screw goes to limit the vacuum advance???
 
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