Original Ignition curves

[MAD]

Dear V8 Guzzlers

Im also programming an electronic ignition with mechanical and vaccum advance for my IntIII.
I use the product "123 ignition" I made very good experience with it on my other cars.
All I need at the moment are the original Chrysler Advance curves. Does anybody knows where I can get them?

Regards
Martin

[Steve Payne]

The original advane curves were very reserved.

I find if you put a lot of advance in as quickly as possible the engine will respond very well.

They idle well with 15 to 18 degrees and 30 degrees by the time you are doing 2000rpm. All in say mid 40's by the time you are at 2500rpm.

You will need to take out up to 20 degrees at high throttle openings.

I hope this helps

Steve

[MAD]

Dear Steve

Thank you a lot for this information. Incredible that the curves seem not to be available.
It's a complete other story if you ask Bosch. I've got all the curves for the NSU Ro80 to set up the 123 ignition.

But nevertheless. Just for understanding, you mean about 45° at 2500 - rev limit?
with or without vacuum advance?

I'll try to figure out the original curve (or what is possible in my over 30 year old distributor) on a testrig to have plus minus a good starting point.

I think such a curve would be beneficial also for other drivers.

Regards
Martin

[Steve Payne]

Hi Martin

Yes 45 degrees with advance.

Good luck and let me know what you find.

Steve

[thomaslk]

Hi Martin,
in my engine workshop manual i can find for most distributors the advance degrees for 600/750/2200 distributor revs. So if you pass me your distributor# i can check these figures.
On the other hand all sources i know support Steve´s settings of about 15 +/-3 degrees @ idle and max of about 35° +/- 3 degr @ 2500 engine revs - vacuum disconnected.

rgds
Thomas

[MAD]

Salut Thomas

I checked the number of my distributor... 2642730. Im my engine manual all numbers should start with a 3. I'm sure that my distributor is not the original one because it has a mechanical breaker contact and no ECU. breaker contact feeds the coil like a simple "normal" ignition system. I mean the car runs/ starts well in every condition, but I would like to have the original setup.
Acc to my handbook should my 440 not H.P. be equipped with 3874173.
Therefore I can figure out the points given there to evaluate the igition curve.

Regards
Martin

[thomaslk]

Hi Martin,
i could not find any info regarding 2642730 - as you said all specified 440 dizzys start with 3874xxxx and even xxxxx2730 was not in my specs.
Your target dizzy 3874173 had the following specs according to my manual:
1.0 to 3.5° @600
3.5 to 6.0° @750
8.0 to 10.0° @2000 distributor revs
Pls note this are all distributor degrees and distributor revs so multiply by 2 to have crank values.
vacuum values:
0.5 to 2.5°@8"vacuum
9.0 to 11.0°@14"vacuum
also distrib. values

In my distributor i limited the max advance by small spacers to run with about 15°@idle and 38°@max advance (crank values) and used the light Mopar performance springs which give full advance @ quite low revs.
There is a good documentation available in the Mondayclub website - thx Kerry et al.

Hope it helps
rgds
Thomas
2211-1490

[MAD]

Dear all

In the meantime I drove about 700 miles with the adapted 123 ignition and its a real pleasure to drive. Idling is just perfect and the accelleration performance is very conclusive.

So I really can recommend this ignition system as an alternative to all those MSD's and all that stuff which is in my opinion not needed for "normal" street use.

Regards
Martin

[Patric]

Thread Resurrection!

I'm about to go down this route myself and install an adjustable distributor on the Red Baron. Having of course read and re-read the very good JMC article I'm surprised just how agressive an advance curve they used.

Most people seem to be happy with the way the factory sets up these distributors:

From the factory it has 2 medium weight springs installed and approx. 20-22 of mechanical advance dialed in. Run it as-is and set the base timing at 15-16 @ idle and check the total timing. It will be all in by 3000 rpm and you should have ~36-37* total.

This works great with the majority of mild pump gas street builds

The manual says:

...generate a performance ignition advance curve that typically beginns at 1200 RPM and generates 20-22 DEG crankshaft advance that is fully in by 3200-3300 RPM

Compare these figures to the ones in the JMC article:

The point at which maximum advance is reached is another deciding factor in the engines performance. The standard 440 distributor gives maximum advance by 2600rpm. The distributor fitted to the Six Pack or Magnum engines gives maximum advance at 1700. This will make a stock 440 much more responsive.

Why the considerable difference?
I do drive my car @4000 RPM and more on the Autobahn so having total advance coming in way below 2000 RPM certainly sounds rather radical.

Opinions please!

[Steve Payne]

Your going to struggle to fit a fully adjustable distributor as they are no longer available new.

The amount of advance these engines will take is surprising with no pinking, I presume the original figures must be something to do with emissions and maybe they are playing it safe as to much advance can kill and engine quickly if poor quality fuel is used.

There are a lot of fully mapped ignition systems available like this http://www.aldonamethyst.co.uk/" onclick="window.open(this.href);return false;. You can keep the standard distributor and just dial in the amount of advance you need via a laptop. It uses the standard distributor and coil and just delays the signal to give the desired advance curve.

Steve

[Patric]

Your going to struggle to fit a fully adjustable distributor as they are no longer available new.

FireCore now produce them:
http://chucker54.stores.yahoo.net/maravaadeldi.html

They also got pretty good reviews in the Mopar press

Bought mine from Jegs for USD 163

The amount of advance these engines will take is surprising with no pinking, I presume the original figures must be something to do with emissions and maybe they are playing it safe as to much advance can kill and engine quickly if poor quality fuel is used.

I'm curious Steve: what happens after total advance comes in? There has to be a reason why today's Americans don't go for such a steep advance curve.

There are a lot of fully mapped ignition systems available like this http://www.aldonamethyst.co.uk/" onclick="window.open(this.href);return false;. You can keep the standard distributor and just dial in the amount of advance you need via a laptop. It uses the standard distributor and coil and just delays the signal to give the desired advance curve.

That might be my next step. For the time being I'd like to find out if a tweaked traditional setup is "good enough". I don't race my car, certainly not with the engine as it is. Hence going fully digital seems like overkill at the moment.

[Patric]

Well, this is going to be helpful:





Since the springs in the original MP kit (made by Mallory) are more or less the same I wonder if the JMC article talked about distributor instead of crankshaft revolutions.

[Steve Payne]

The curve on my car with mapped ignition is more aggressive than any of those.

This is one case when more is better to a certain degree( no pun intended ). If it pinks retard about 4 degrees and see what you get.

You have to make a decision on what fuel you are going to use when you do this.

If you want the max advance you will need to use higher octane fuel but with more advance you often save fuel so the extra expense is often offset.

The biggest advantage with more advance is you get better throttle response.

Steve

[Patric]

You also managed to fit a cold air intake I seem to remember? TBH I never found throttle response a problem on the Interceptor.

[PeterS]

Hi , I done a way with my distributor, this is what we did http://www.autosportlabs.org/viewtopic. ... nsen#12910" onclick="window.open(this.href);return false;