Still trying to map out a timing curve

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Mopar to ya

Mopar to ya

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If anyone has an MSD 6AL-2 programmable, I need help with plotting timing curves. Or if you are knowledgeable enough to throw out some advice, that will help as well. I have a 408 stroker with 11.8:1 compression, Comp Cam 242/248 Dur@ .050, .3660/.3630 lift @ .050, 112° lobe sep. 549/544 gross valve lift, and am running a Holley 750dp. My old MSD 6 box worked great. I wanted more adjustability and went programmable. This system retards up to 25 degrees timing. My centrifugal advance is locked and the timing is set at 36 degrees. I typically run 38 degrees total on race gas and 34 on 93 octane, so I started in the middle. I set up this curve to remove 25 degrees timing until 600 rpm, then remove 17 degrees until 1000 rpm, then ramping up to full timing at 4000 rpm. Basically I'm starting the car at 11 degrees, idling at 19 and then ramping up. I have a noticeable lack of power and a stumble / cut out at around 4500 rpm. It stumble and will not burn out. I'm looking for advice on timing. Any and all would be appreciated. I am adding a screenshot of my timing plot. Burnout rev limiter is set at 5000 rpm and total rev limit is set at 6400. I am not using the launch rev limiter.

View attachment Timing curves.jpg
 
I thought 3000 was good, but looking at original MSD distributor curves, it depends on your springs. I had two silver springs, but have no way of knowing if they were heavy or light. Stock MSD Pro Billet dizzy with heavy silver springs is all in at about 5300. Two light silvers it's all in at around 2400. I'm hoping for great advice, but otherwise will play with all different curves.
 
All in RPM should be below converter stall speed.

MSD pro billet distributor OOTB set ups are about as dumb as it gets.
 
I would leave the laptop hooked up and drive it up to the problem rpm's and see what the timing and rpm's are according to the MSD unit. You may be hitting your rpm limit for the burnout limiter, and I dont recall if you said you hooked that up or not. That may be an issue if the unit is expecting to see a circuit there and there isnt one. Try disabling the burnout limiter and see what happens...

You should be at full advance well before that rpm. Your motor would probably like to see full advance fairly quickly, like 2500 rpm's. You definitely want it fully advanced by your cruising rpm, and with your OD that may be the deciding factor.
 
I hope the plot shown is not what you are using. The stair step at the low end may lead to a few problems. Things like hard starting, poor take-off, stalling at idle, poor idle speed regulation. But I never worked with MSD, so I might be wrong since no mention of those problems.

While you suggest the system does 25 degrees of control, the timing map suggests 35.
 
You seem to be all over the place. At one point you are saying timing is 'locked out' but only refer to centrifugal advance. Then you are describing advance curves where you have timing retarded at the same time advancing very slow. What exactly are you trying to achieve?

I agree with the above assessment about timing being all in by 2,500 or even earlier. As an example, some of the old MP race distributors came with curves that were 'all in' by 1,200 rpm which was essentially like having locked out timing. The reasoning behind a very quick curve like that is that cars with big cams (like yours) tend to idle over 1,000 rpm, produce low vacuum and spend little time under part throttle operation. Why mess with an advance curve if the combo does not require it? People also run these types of curves on the street without issue, (like me) you just need to make sure you don't detonate.

Your initial timing could be higher as well, no need to retard it much if at all unless your starter can not handle it and it kicks back. I have 20 degrees initial on my solid-cammed small block and it starts fine, no starter kickback. I had it at 26 at one point and it still started fine.

If I can infer what you are trying to do, you need to figure out how to arrive at your desired total advance of 36. Generally, the idea is to limit mechanical advance to be able to arrive at the total (36) while running as much initial as your combo will allow. This is likely somewhere between 18-22 depending on how much vacuum you have at idle. Your car may be somewhere else but whatever the initial number is, you should figure out what it 'likes' first. So let's just say you wind up with 20 initial and it starts and idles OK. Add 16 mechanical (centrifugal) to that number to get 36. That's it.

So now that you have your total figured, your 'timing curve' (or advance)should have any and all 'timing' stop advancing or be 'all in' by 2,000 rpm or so. 4,000 rpm or anything above 3,000 rpm for that matter in a combo like yours is way too late to not have the timing fully advanced. Essentially your timing is being retarded until that point which is probably why it runs like crap. Luckily you have a programmable ignition which should make it pretty easy to nail down. Obviously you have to make some adjustments, take it for a ride and see what happens but that should be your procedure.

Without the digital gizmo you'd be welding advance plate slots and sitting there with a timing light and a vacuum gauge trying to dial it in. (like me)

Hope that helps.
 
KitCarlson said:
I hope the plot shown is not what you are using. The stair step at the low end may lead to a few problems. Things like hard starting, poor take-off, stalling at idle, poor idle speed regulation. But I never worked with MSD, so I might be wrong since no mention of those problems.

While you suggest the system does 25 degrees of control, the timing map suggests 35.
Click to expand...

You have to remember that this is backward. The ignition retards timing. I have it locked in with no centrifugal advance at 36 degrees. It is taking away 25 degrees of timing at start up, leaving it at 11 degrees. Then between 600 and 1000 rpm, or idle, it is taking away 17 degrees leaving it at 19 degrees idling. Then I have it ramp up the timing until all in at 4000 rpm.
 
rmchrgr said:
You seem to be all over the place. At one point you are saying timing is 'locked out' but only refer to centrifugal advance. Then you are describing advance curves where you have timing retarded at the same time advancing very slow. What exactly are you trying to achieve?

I agree with the above assessment about timing being all in by 2,500 or even earlier. As an example, some of the old MP race distributors came with curves that were 'all in' by 1,200 rpm which was essentially like having locked out timing. The reasoning behind a very quick curve like that is that cars with big cams (like yours) tend to idle over 1,000 rpm, produce low vacuum and spend little time under part throttle operation. Why mess with an advance curve if the combo does not require it? People also run these types of curves on the street without issue, (like me) you just need to make sure you don't detonate.

Your initial timing could be higher as well, no need to retard it much if at all unless your starter can not handle it and it kicks back. I have 20 degrees initial on my solid-cammed small block and it starts fine, no starter kickback. I had it at 26 at one point and it still started fine.

If I can infer what you are trying to do, you need to figure out how to arrive at your desired total advance of 36. Generally, the idea is to limit mechanical advance to be able to arrive at the total (36) while running as much initial as your combo will allow. This is likely somewhere between 18-22 depending on how much vacuum you have at idle. Your car may be somewhere else but whatever the initial number is, you should figure out what it 'likes' first. So let's just say you wind up with 20 initial and it starts and idles OK. Add 16 mechanical (centrifugal) to that number to get 36. That's it.

So now that you have your total figured, your 'timing curve' (or advance)should have any and all 'timing' stop advancing or be 'all in' by 2,000 rpm or so. 4,000 rpm or anything above 3,000 rpm for that matter in a combo like yours is way too late to not have the timing fully advanced. Essentially your timing is being retarded until that point which is probably why it runs like crap. Luckily you have a programmable ignition which should make it pretty easy to nail down. Obviously you have to make some adjustments, take it for a ride and see what happens but that should be your procedure.

Without the digital gizmo you'd be welding advance plate slots and sitting there with a timing light and a vacuum gauge trying to dial it in. (like me)

Hope that helps.
Click to expand...

There is no vacuum or mechanical advance. The advance it locked out. The only curve it gets is the one I program in. It is set at 36 degrees and will not move from that point. The curve I have pictured gives me start up timing of 11 degrees, idling at 19 degrees, then ramping up to 36 degrees by 4000 rpm. My rev limiter is set at 6400 and the burnout rev limiter that is set to go as long as the line lock is depressed is set for 5000 rpm. I'm trying to maximize my power and get a very usable timing curve.
 
The start retard is a cool feature as long as it fires right off at the flick of the key, if it doesn't I would take some retard out of that feature until it does with the engine HOT.

That engine should idle around 1000 RPM or so. Your engine is going to like more Initial timing than 19* , I would say in the 23-24* Range at Idle. It will be way more crisp off idle than starting at 19, It will be lazy where you have it at. Your all in timing should be in the 2200-2500 RPM Range. That is how I would set it up if it were me. I have my stroker rev limiter at 7200 RPM. Yours is pretty low in my opinion. Right when you are in the power it is going to bang off the limiter.

Just noticed you got 4:10 gears too. You are going to definitely hit that limiter real fast.
 
Mad Dart said:
The start retard is a cool feature as long as it fires right off at the flick of the key, if it doesn't I would take some retard out of that feature until it does with the engine HOT.

That engine should idle around 1000 RPM or so. Your engine is going to like more Initial timing than 19* , I would say in the 23-24* Range at Idle. It will be way more crisp off idle than starting at 19, It will be lazy where you have it at. Your all in timing should be in the 2200-2500 RPM Range. That is how I would set it up if it were me. I have my stroker rev limiter at 7200 RPM. Yours is pretty low in my opinion. Right when you are in the power it is going to bang off the limiter.

Just noticed you got 4:10 gears too. You are going to definitely hit that limiter real fast.
Click to expand...

The best part is I can program in a new curve in about two minutes. My engine does not like 6000 rpm, much less 7200. It is screaming and has nothing more to give. I'll jack up the idle timing and change the all in, and then disable the rev limiters and see what happens. Oh, and the timing is instant at key on. It's a pretty cool set up. I have a switch installed that lets me do what they call a step curve. It basically overrides the main program when the switch is on. I can use the switch when I run pump gas and keep the timing down a bit, or turn the switch off and let it fly at full timing on race gas.
 
Mopar to ya said:
The best part is I can program in a new curve in about two minutes. My engine does not like 6000 rpm, much less 7200. It is screaming and has nothing more to give. I'll jack up the idle timing and change the all in, and then disable the rev limiters and see what happens. Oh, and the timing is instant at key on. It's a pretty cool set up. I have a switch installed that lets me do what they call a step curve. It basically overrides the main program when the switch is on. I can use the switch when I run pump gas and keep the timing down a bit, or turn the switch off and let it fly at full timing on race gas.
Click to expand...

Wow. Don't you have Eddy Ported Heads?

Mine pulls hard easily to 6800 Rpm crisp and clean too, does not miss a beat. 410 CI Pump Gas 9:1 Compression, Iron Headed RHS by Brian at IMM with Solid Roller Cam spec'd by Brian. .634 Lift at the valve and small 242@50 Duration.

Sounds like a very versatile ignition box you have.
 
I have Eddy RPM light ported heads, 12:1 compression, Comp Cam roller rocker and hydraulic roller lifter. Doesn't like high rpm.
 
Mopar to ya said:
There is no vacuum or mechanical advance. The advance it locked out. The only curve it gets is the one I program in. It is set at 36 degrees and will not move from that point. The curve I have pictured gives me start up timing of 11 degrees, idling at 19 degrees, then ramping up to 36 degrees by 4000 rpm. My rev limiter is set at 6400 and the burnout rev limiter that is set to go as long as the line lock is depressed is set for 5000 rpm. I'm trying to maximize my power and get a very usable timing curve.
Click to expand...

I believe you are making things more complicated than need be. If your timing is 'locked' like you say, there is NO ADVANCE CURVE. If your timing was locked, the car would start and idle at 36 degrees and stay at 36 through whatever rpm you go to. When you have the start up timing at 11, idle at 19 then 'ramp up' to 36 at 4,000, THAT by definition is an advance curve.

Like I said previously and what Louis has corroborated, your initial timing should be at least 20, probably 22-24. Forget about start retard. You may have to experiment with how much initial can be tolerated before the starter kicks back, if it does at all.

Again, the general idea is to run as much initial as you can and limit mechanical to arrive at your total. Once you get your initial dialed in, focus on getting the remainder of the timing all in by 2,000 rpm because 4,000 rpm is 10 years too late. Those two ideas are really all you should be concerned with.

I think the fancy programmable gadgetry is adding unnecessary complexity. You got your total advance number, all you have to do is figure out how quick to arrive at it and how far you need to go from your initial.
 
The box controls the curve. He times it at 36* and the box pulls timing to hit the point along the plotted curve.

The distributor is locked out, no mechanical advance in it. Only triggers the box 36* BTDC in his case.

Replot it so you have a 21 initial, 15 advance curve with it all in at 2200-2500.
 
crackedback said:
The box controls the curve. He times it at 36* and the box pulls timing to hit the point along the plotted curve.

The distributor is locked out, no mechanical advance in it. Only triggers the box 36* BTDC in his case.

Replot it so you have a 21 initial, 15 advance curve with it all in at 2200-2500.
Click to expand...

I understand about the box. In this case though, it seems to be adding confusion. He needs to do the leg work and use the box as a tool just to make the changes, not use the box to do the leg work. :study:
 
rmchrgr said:
I believe you are making things more complicated than need be. If your timing is 'locked' like you say, there is NO ADVANCE CURVE. If your timing was locked, the car would start and idle at 36 degrees and stay at 36 through whatever rpm you go to. When you have the start up timing at 11, idle at 19 then 'ramp up' to 36 at 4,000, THAT by definition is an advance curve.

Like I said previously and what Louis has corroborated, your initial timing should be at least 20, probably 22-24. Forget about start retard. You may have to experiment with how much initial can be tolerated before the starter kicks back, if it does at all.

Again, the general idea is to run as much initial as you can and limit mechanical to arrive at your total. Once you get your initial dialed in, focus on getting the remainder of the timing all in by 2,000 rpm because 4,000 rpm is 10 years too late. Those two ideas are really all you should be concerned with.

I think the fancy programmable gadgetry is adding unnecessary complexity. You got your total advance number, all you have to do is figure out how quick to arrive at it and how far you need to go from your initial.
Click to expand...

You aren't understanding the situation. Yes, the distributor never turns for advance. Yes, it is locked in at 36 degrees. The MSD box retards the timing to whatever I program it to be at ignition on. Therefore, I am not at 36 degrees at start up. I have set it for 11 degrees at start up, 19 at idle and 36 all in. I'm glad for the help, but the fancy programmable gadgetry is what will help me get the most from my motor. There are those who thought electronic ignition was un unnecessary complexity, but we have learned otherwise.
 
crackedback said:
The box controls the curve. He times it at 36* and the box pulls timing to hit the point along the plotted curve.

The distributor is locked out, no mechanical advance in it. Only triggers the box 36* BTDC in his case.

Replot it so you have a 21 initial, 15 advance curve with it all in at 2200-2500.
Click to expand...

I just pulled the distributor and made sure it was seated properly. I had changed the o-ring and wasn't convinced it was seated all the way as it uses a gasket as well. I put in a smaller o-ring and threw away the gasket. It is seated tight now. I will plot a curve as you suggest and let you know how it goes. Thanks, Crackedback, you are always very helpful.
 
Mopar to ya said:
You aren't understanding the situation. Yes, the distributor never turns for advance. Yes, it is locked in at 36 degrees. The MSD box retards the timing to whatever I program it to be at ignition on. Therefore, I am not at 36 degrees at start up. I have set it for 11 degrees at start up, 19 at idle and 36 all in. I'm glad for the help, but the fancy programmable gadgetry is what will help me get the most from my motor. There are those who thought electronic ignition was un unnecessary complexity, but we have learned otherwise.
Click to expand...

OK champ, sounds like you got a better handle on it than I do.

Crack yourself open an ice cold beer and toast a job well done.
 
Okay, when I removed the distributor to lock the advance, the o-ring was in pieces and I replaced it. It also had a gasket, which I don't remember using, but I put it back in. I was never quite convinced I got the distributor to sit all the way in. Today I pulled the distributor, threw away the gasket and put in a smaller o-ring. I had to go two sizes smaller to get it to drop all the way in. Then I set the timing at 36 degrees. I used Crackedback's suggestion of 21 initial and all in at 2500 or so. Actually, I went 21 initial, 23 at idle, and all in at 2500. I also removed the rev limits. It runs beautiful. Hard and fast. I am going to add the rev limits back in and see what happens. I'm much happier now. Now I can play a bit and see what works best.
 
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