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Spark Advance Curve
#1289551
08/22/12 09:53 AM
08/22/12 09:53 AM
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Joined: Mar 2011
Posts: 183
Charleston, SC
bronco9588
OP
member
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OP
member
Joined: Mar 2011
Posts: 183
Charleston, SC
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Hi Everybody,
I just purchased a 6al-2 programmable MSD box and I can control the spark advance electronically throughout the spark advance curve. The problem is... I have no idea what the spark advance curve should look like and general tuning tips for advancing or retarding the curve. Thanks for your help. 400 chrysler stock with 346 heads.
'73 Charger Petty Blue, Black Vinyl, and Gill Slits
727 torque-flight
400 BB Chrysler
8 3/4 rear
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Re: Spark Advance Curve
[Re: bronco9588]
#1289552
08/22/12 10:36 AM
08/22/12 10:36 AM
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Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
BradH
Taking time off to work on my car
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Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
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You're in over your head for what should be a very basic setup for a stock engine. Send the MSD box back for a refund and contact Don Gould at FBO Systems (4secondsflat.com) about having him set up a good ignition system for your car.
Last edited by BradH; 08/22/12 10:40 AM.
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Re: Spark Advance Curve
[Re: BradH]
#1289554
08/22/12 01:01 PM
08/22/12 01:01 PM
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Joined: Mar 2011
Posts: 183
Charleston, SC
bronco9588
OP
member
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OP
member
Joined: Mar 2011
Posts: 183
Charleston, SC
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Quote:
You're in over your head for what should be a very basic setup for a stock engine. Send the MSD box back for a refund and contact Don Gould at FBO Systems (4secondsflat.com) about having him set up a good ignition system for your car.
Thanks dude... Like I want or need to spend more money on an ignition system. I understand what I want, but have no idea what curve the stock ignition system uses.
To explain. I have a 400 and am planning on swapping out to a modified 440. I like the rev limiters, boost curve (supercharger), and nos capabilities of the 6530. I understand it is overkill for the stock 400, but it should work none the less. I want to get comfortable with this ignition on the 400 and step up to the 440 in due time. I like the flexibility the box gives me, and am willing to spend the time to get it to work. I purchased it for the 440 with no intention of running it on the 400, but current ignition problems have me looking to this box for an intermediate fix.
Thanks for your NOT requested advertisement and NOT useful timing specifications. What maybe is over YOUR head in technology is not over someone else's head.
'73 Charger Petty Blue, Black Vinyl, and Gill Slits
727 torque-flight
400 BB Chrysler
8 3/4 rear
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Re: Spark Advance Curve
[Re: bronco9588]
#1289555
08/22/12 01:37 PM
08/22/12 01:37 PM
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Joined: Oct 2003
Posts: 7,506
Az
Crizila
master
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master
Joined: Oct 2003
Posts: 7,506
Az
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Quote:
Quote:
You're in over your head for what should be a very basic setup for a stock engine. Send the MSD box back for a refund and contact Don Gould at FBO Systems (4secondsflat.com) about having him set up a good ignition system for your car.
Thanks dude... Like I want or need to spend more money on an ignition system. I understand what I want, but have no idea what curve the stock ignition system uses.
To explain. I have a 400 and am planning on swapping out to a modified 440. I like the rev limiters, boost curve (supercharger), and nos capabilities of the 6530. I understand it is overkill for the stock 400, but it should work none the less. I want to get comfortable with this ignition on the 400 and step up to the 440 in due time. I like the flexibility the box gives me, and am willing to spend the time to get it to work. I purchased it for the 440 with no intention of running it on the 400, but current ignition problems have me looking to this box for an intermediate fix.
Thanks for your NOT requested advertisement and NOT useful timing specifications. What maybe is over YOUR head in technology is not over someone else's head.
Not answering for BradH, but what you bought will work just fine. Just a lot of $ for your existing set up. When you decide to upgrade to a more performance set up, then you will be better able to justify the $. If you can dial in my suggested settings, you will be in the ball park for your existing stuff. 
Fastest 300
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Re: Spark Advance Curve
[Re: bronco9588]
#1289556
08/22/12 01:53 PM
08/22/12 01:53 PM
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Joined: Aug 2005
Posts: 403
30 miles west of EuroDisney
fbernard
mopar
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mopar
Joined: Aug 2005
Posts: 403
30 miles west of EuroDisney
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Technically, this ignition is designed to be used with a locked-out distributor, and a MAP Sensor for vacuum advance (instructions suggest the MAP Sensor PN 23111 for N/A engines). This means : - you should determine optimal initial advance setting using this method for example. - you should lock the timing on the distributor (how depends on your distributor type). - you should decide where on the RPM curve you want the total advance all-in. If that was a drag car, I'd say a few hundred RPMS after your convertor stall speed, but for a street converter, that would be too low. Somewhere around 3000 RPM would be a good start. Max advance for a BB is usually 38°. - Now you have the initial timing value, and the final "mechanical" advance RPM level, you can set a straight curve for a start. I see no reason for further tweaking for your current engine, you may need that for the next mill. You could change the end of the curve so that there's an advance decrease in the high RPM zone, but the rev limiter takes care of that. You may change the start of the curve for easier starts (like having almost no advance at 0 RPM and ramping up to whatever the initial timing is around 700 RPM but your 400 will likely not need much in that area) You don't absolutely need the MAP sensor for a start, but it's useful if you car sees some road miles. The original Mopar documentation for the electronic ignition conversion says total ignition advance can be up to 56° for a BB, that's around 18° of vacuum advance, so you'd want something like that at the maximum vacuum your engine pulls when cruising (you'll need to know how much vacuum your engine pulls cruising at 3000 RPM, get a vacuum gauge with a long tube so you can take it for a ride). If you use the 6530 and a distributor with a functional mechanical advance, the programmed curve should be flat, since the box won't be managing the advance curve. Using a "normal" advance curve with a non-locked-out dist will produce detonation!! I don't know if you can lock the dist for mechanical advance and retain the vacuum advance (this would be easier than installing the MAP sensor).
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Re: Spark Advance Curve
[Re: fbernard]
#1289557
08/22/12 02:55 PM
08/22/12 02:55 PM
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Joined: Mar 2011
Posts: 183
Charleston, SC
bronco9588
OP
member
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OP
member
Joined: Mar 2011
Posts: 183
Charleston, SC
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1) I have an eddy 1406, so I have a MAP vacuum port. It would look butt ugly, but I could take some tubing and a pair of hose clamps and get Vacuum advance capabilities. I kinda like that idea actually.
2) For Starts, I could wire in the boost retard. Once I get that all ironed out... I could tie that in with the starter relay.
'73 Charger Petty Blue, Black Vinyl, and Gill Slits
727 torque-flight
400 BB Chrysler
8 3/4 rear
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Re: Spark Advance Curve
[Re: fbernard]
#1289558
08/22/12 03:12 PM
08/22/12 03:12 PM
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Joined: Mar 2011
Posts: 183
Charleston, SC
bronco9588
OP
member
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OP
member
Joined: Mar 2011
Posts: 183
Charleston, SC
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Okay... so I think I almost have it figured out.
1) Anyways, what is the easiest "start up" ignition timing? Anything I am looking or listening for here?
2) Can you go more into depth on Vac advance? Do you have a link for that?
More Vac = Less Load = More Advance? or did I get that flipped around?
'73 Charger Petty Blue, Black Vinyl, and Gill Slits
727 torque-flight
400 BB Chrysler
8 3/4 rear
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Re: Spark Advance Curve
[Re: BradH]
#1289560
08/22/12 06:59 PM
08/22/12 06:59 PM
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Joined: Mar 2011
Posts: 183
Charleston, SC
bronco9588
OP
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OP
member
Joined: Mar 2011
Posts: 183
Charleston, SC
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...again, NOT very helpful. Not trying to flame, but what one person intends with their car is very different than what you would intend with yours. I am aware of a cheaper solution, but have different plans. Furthermore, ATFQ... this thread has nothing to do with what type of ignition I should buy. It has everything to do with ignition timing. I'm sure that 50 year old tech isn't above your head but I am admitting it is mine.
'73 Charger Petty Blue, Black Vinyl, and Gill Slits
727 torque-flight
400 BB Chrysler
8 3/4 rear
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Re: Spark Advance Curve
[Re: fbernard]
#1289561
08/22/12 08:54 PM
08/22/12 08:54 PM
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Joined: Mar 2011
Posts: 183
Charleston, SC
bronco9588
OP
member
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OP
member
Joined: Mar 2011
Posts: 183
Charleston, SC
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Quote:
The advance setting which gives the best vacuum (checked with a timing light) is the ideal initial timing you should be using. Write it down. Depending on your camshaft, compression, etc., it could be rather high.
So the car likes about 20 degrees timing. I watch the vacuum indicator and it seems to enjoy many many degrees. If I go one over, chug chug chug. Not really a bell curve on manifold pressure. Is this most likely an aftermarket cam?
Quote:
A part-throttle drive uphill or a WOT pass should be made confirm that there's no pinging. In case of pinging, back off 2° and retry.
Deciding this may have been the issue, I cut back the timing about 3 degrees. Everything seems great.
I still plan to wire up the MSD to get comfortable with the box.
'73 Charger Petty Blue, Black Vinyl, and Gill Slits
727 torque-flight
400 BB Chrysler
8 3/4 rear
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Re: Spark Advance Curve
[Re: bronco9588]
#1289562
08/22/12 09:29 PM
08/22/12 09:29 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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You really need to put it on a chassis dyno and run as much advance as possible without any pinging... that way you can watch a vac gauge and listen and then do a plug check... along with a A/F meter 
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Re: Spark Advance Curve
[Re: MR_P_BODY]
#1289563
08/22/12 09:56 PM
08/22/12 09:56 PM
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Joined: Mar 2011
Posts: 183
Charleston, SC
bronco9588
OP
member
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OP
member
Joined: Mar 2011
Posts: 183
Charleston, SC
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you do a plug check even with a lambda sensor?
'73 Charger Petty Blue, Black Vinyl, and Gill Slits
727 torque-flight
400 BB Chrysler
8 3/4 rear
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Re: Spark Advance Curve
[Re: bronco9588]
#1289565
08/22/12 10:06 PM
08/22/12 10:06 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
you do a plug check even with a lambda sensor?
I do... who's to say the gauge is correct and not
showing something dumb... you want to burn up a
engine for 5 minutes worth of work.... timing also
shows up on the plug(I cant say about the cruise though)
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Re: Spark Advance Curve
[Re: bronco9588]
#1289568
08/22/12 11:52 PM
08/22/12 11:52 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Quote:
Quote:
you do a plug check even with a lambda sensor?
I do... who's to say the gauge is correct and not
showing something dumb... you want to burn up a
engine for 5 minutes worth of work.... timing also
shows up on the plug(I cant say about the cruise though)
Any changes to spark timing when using higher octane fuels such as e85?
It should still read the same on the strap
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Re: Spark Advance Curve
[Re: bronco9588]
#1289572
08/23/12 12:49 AM
08/23/12 12:49 AM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Quote:
It should still read the same on the strap
Not really familiar with "strap"
Quote:
I just run a basic 10+ year old 6-A MSD not even a rev limiter because of the reasons you started the post. Definately not a plug n play deal.........good luck.
The 6AL-2 Programmable is entirely a different beast than the other 6 boxes.
Ground strap
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Re: Spark Advance Curve
[Re: BradH]
#1289575
08/25/12 12:24 AM
08/25/12 12:24 AM
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Joined: Oct 2003
Posts: 7,506
Az
Crizila
master
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master
Joined: Oct 2003
Posts: 7,506
Az
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Quote:
Here's a "no 'tude" response to the OP's post:
- A stock 400 is low compression and may tolerate up to about 20 degrees initial timing, but verifying the hot-start behavior will be important to determine how much it'll accept and still start w/o hard cranking
- Total timing considering the low compression and open chamber design is probably limited to somewhere in the 34-36 degree range; California-spec pump fuel is an even lower octane than most of the country (my local pump swill is 93-octane w/ 10% ethanol blended) and that'll probably cap the max advance at 32-34
- Depending upon gearing & converter stall speed, the advance curve should probably start around 1200-1400 RPM and reach full advance out about 3000 RPM
- Vacuum advance should be limited to 8-10 degrees to play it safe; one responder above suggested as much as 16 degrees, but that much will likely cause pre-ignition issues under high-vacuum cruise conditions
- Carb & ignition tuning are tightly related, especially since big changes in the initial timing curve can result in significant idle speed changes and require associated mixture adjustments
The programmable box is a cool unit, but it seems like major overkill for the current application.
I suggested a vacuum advance of 16 degrees. I also suggested an initial of 12, not 20 degrees. I ran my suggested numbers in a low compression 400 in a 78 Newyorker ( a real heavyweight ) with no problems. Honestly, you have a lot of latitude with that motor, no matter what gas you use. Ran my Newyorker back and fourth from the midwest to the coast several times on regular. No problems.
Fastest 300
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