Help with ignition timing

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George R

George R

Mopar Nutcase
Joined
Oct 29, 2007
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Location
Trumbull, CT
I bought a remanufactured distributor, a dial back timing light, a tach & dwell meter and a set of advance springs for the car. Now all I need are real world specs on what to set the advance and initial to.
Here is the car:
Stone stock 1969 Dart 340 with a stock 727 trans and 323 rear gears. Car has the stock HP manifolds, and the original AVS carb.
What should the initial timing be set to?
Where do I want to be with the mechanical advance all in?
Should I use the vacuum advance, and if so, should all adjustments be made with it attached or disconnected?
When people say set timing at full advance to XXº, do they mean with or without vacuum advance??
Looking for real settings from you more experienced guys. I am as green as they come when it comes to Mopars! LOL

Thanks in advance. (no pun intended :D )

George
 
George, usually total advance is more important then initial because without tailoring the curve you usually won't end up with the desired initial after setting the full advance/total timing w/stock distributor.
When we speak total timing we are talking about the total amount of mechanical advance in the distributor combined with initial, so in other words say you have 5* initial before top dead center @ idle, then if you rev the engine to 4000 and check the timing again you would probably find 30* timing, thats the mechanical advace in the distributor basically advancing with RPM so 5* initial + 25* of mechanical =30* .

Total timing does not account for the vac advance, thats something to be looked at by it's self[IMO] And if your gonna run vac advance you need to dial it in after you figure out your timing curve.

Now tipically for 'power' you would need to find a way to get as much initial the engine can 'start' with [no kick back] and all the total timing it can stand without detonating along with the rate/speed it advances, which is where the tailoring comes into play.
This is where you would weld up/pin the slots in the wieghts inside the distributor IF STOCK and where you would simply change bushings and springs in a MSD or most other high end ditributors.

With a stock piece you could put the mr.gasket springs in and at least speed the advance but that alone doesn't fix it, time to weld or what we used to do was take the haevy spring off all together and only run the lighter one[1 spring] this will give you more like 18* @ idle if it's set to 34*@/around 1800-2200RPM however the intial can varie it's self with idle lowering and such so it's not something I would do on a freeway car [which is where it would be noticable, as you came to a stop at the off ramp]

To rap this up I'll say put [1] light spring in place of the heavy one in the ditributor and set the total timing [timing at 3000+RPM] to 34* and call it good.

I'm gonna stop here and if there are any more direct questions just ask.
 
340 hit most of the stuff, but, I have a differing opinion on the set it at 34* and call it good.

I'd set your initial with a vacuum gauge. Advance the idle settings keeping the rpm consistent until you reach the highest reading, then back it off 1" and reset idle RPM. As long as it doesn't kick back on the starter, you're good. Mopar distributors generally have a bunch of mechanical advance in them... too much, IMHO.

Then tailor the mechanical advance, welding up or jbweld slots, to reach the desired total advance number that doesn't result in detonation.

Nice write up 340!
 
George,

You can put in one light advance spring. If this is the M/P electronic distruibutor then you can run full mechanical advance. I have a plugged vacuum hose on mine just for "looks".

I run my idle speed up to 2600rpm and dial in for a total of 36*. Set the dial on your light to 36* and when the crank timing mark and the zero line up, then tighten down the distributor. Back off your idle speed to whatever idle speed you prefer ( I run 1000rpm in neutral) and now check your timing. This will be your "initial" timing and I bet it is right around 12-13* (using the dial on the timing light- turning back until the two timing marks line up again).

I had my distributor "curved" by a pro because I discovered that the first guy who curved the distributor didn't fill in the advance weight slots so at 2400rpm it was at 36*, but at full tilt rpm, my 340 was advanced all the way to 48*!!
I now have a total mechanical advance in the distributor of 36*. I run my initial timing at 20* @ 1000rpm. Idles great, awesome throttle response!
 
I ran the MP electronic distributor in mine and it has 25 degrees on the distributor. I like to run 13 initial and 38 total (vacuum disconnected while checking). I found this chart on another forum recently:

dist. degrees X 2 + initial= total


dist. 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
 
Thanks for all the help guys.
If it ever stops raining here, maybe I can apply what you all have taught me.
This is the second rainy weekend in a row in CT!

George
 
George R said:
Thanks for all the help guys.
If it ever stops raining here, maybe I can apply what you all have taught me.
This is the second rainy weekend in a row in CT!

George
Click to expand...

Weather COULD be worse though George !!! We coulda got a foot of snow, or worse yet, another ice storm like the one in November of '02.. THAT REALLY sucked !! Hope U get your 340 running great !!

Kenny
 
Hey Ken!
I hope to have mine running as good as yours does one of these days!
Your car does a wicked burnout!!!

George
 
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