Timing curves - any ideas?

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Mopar to ya

Mopar to ya

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I haven't installed it yet, but I did buy the new MSD 6AL-2 programmable ignition. MSD has instructions on how to lock out my mechanical advance on my Pro Billet distributor, so I will lock that down at 40 degrees. I will play with the initial timing, but I am expecting it to be around 18-19 degrees. The real question is about setting timing curves. I don't know enough to know what the best curves are for power. What info is needed about my motor to make recommendations, and who has ideas? I can program a bunch of different curves and try them out, I just have no idea what kind of curve to build in.
 
Each engine is different. Your's might run good with 18° initial but mine won't hardly run there. My advance curve with 2 light springs might make your's ping. Really the only thing all systems have in common is the total advance within a degree or two. (around 34-5) You will need to tune the advance to your combination. Distributors are different but they basically work the same (advance weights held back with springs and limited with slots) Don't worry about vacuum advance until you get the initial and mechanical dialed in. There's a discussion about this going on right now. http://www.forabodiesonly.com/mopar/showthread.php?t=263737&highlight=distributor+curve

tmm
 
You aren't understanding what I am doing. I lock my distributor down. No mechanical or vacuum advance ever. I set it at my max timing - around 40 degrees, then my initial timing, which needs to be somewhere 18-19 degrees. Then I program timing curves into my MSD box with my laptop.
 
Look at the instruction for the distributor and match one of those. Use graph paper if you need a visual.

40 total sounds like a bunch

Depending on idle rpm and converter, start around 1200-1500 and have it all in at 2300-3000.
 
Where did you come up with 40 ?
Seems like an excessive amount of timing.
What car/motor/ are we talking here ?
 
Johnny Dart said:
Where did you come up with 40 ?
Seems like an excessive amount of timing.
What car/motor/ are we talking here ?
Click to expand...

'73 Dart Sport 408 Stroker / 200R4 / Dana 60 with 4.10

Mopar to ya
Sorry, I didn't realize that the MSD can be set up with your laptop.
 
Mopar to ya said:
I don't know enough to know what the best curves are for power. What info is needed about my motor to make recommendations, and who has ideas? I can program a bunch of different curves and try them out, I just have no idea what kind of curve to build in.
Click to expand...

A good starting point would be 18 initial and 34 total. Build the curve as a straight curve that has full advance at 3500. You can fine tune from there.

As you said you can develop multiple tunes so to speak to run different fuels etc.

Let me advise you of this... Most people here will tell you to run a lot of initial and have a very quick curve. Most people here complain about detonation and speak highly of low compression engines. So you see a relationship here?

with my MPP dist I had 24 inital 32 total and it was in really quick 1600ish. I run 15 inital now and 35 total in by 3500. Car runs cooler and faster. No changein street manners. If the car has a stall of 3500 what is having the total in at 1500 doing for you?
 
Let me see if I'm picking up what you're putting down and we'll go from there...

You have a programmable ignition setup and, if I understand them correctly, most of those boxes/distributors work by taking timing out instead of adding it. You need to lock out the distributor at 40 degrees and your programmable ignition box retards timing to get it where you want it to be, since the ignition box needs to have an event to trigger it ahead of the earliest it will fire.

Is that the general gist? Or do I need to do some reading?

At any rate, in addition to the info we have, your compression, fuel, what heads, and converter would help get you a starting point for a timing curve.
 
roccodart440 said:
A good starting point would be 18 initial and 34 total. Build the curve as a straight curve that has full advance at 3500. You can fine tune from there.

As you said you can develop multiple tunes so to speak to run different fuels etc.

Let me advise you of this... Most people here will tell you to run a lot of initial and have a very quick curve. Most people here complain about detonation and speak highly of low compression engines. So you see a relationship here?

with my MPP dist I had 24 inital 32 total and it was in really quick 1600ish. I run 15 inital now and 35 total in by 3500. Car runs cooler and faster. No changein street manners. If the car has a stall of 3500 what is having the total in at 1500 doing for you?
Click to expand...

I agree with your comments. Over timing over carbing seem to be a couple favorites around here
 
73Scamp318 said:
Let me see if I'm picking up what you're putting down and we'll go from there...

You have a programmable ignition setup and, if I understand them correctly, most of those boxes/distributors work by taking timing out instead of adding it. You need to lock out the distributor at 40 degrees and your programmable ignition box retards timing to get it where you want it to be, since the ignition box needs to have an event to trigger it ahead of the earliest it will fire.

Is that the general gist? Or do I need to do some reading?

At any rate, in addition to the info we have, your compression, fuel, what heads, and converter would help get you a starting point for a timing curve.
Click to expand...

You are correct, sir! I run a total of 38 degrees right now. My initial is 12 with that total. I lock out the dizzy at whatever total I choose and use the MSD box to retard the timing for initial. Then I set the curve. I am running a 408 stroker, 11.8:1compression, Eddy RPM heads lightly ported and matched. I run 93 octane at 34 degrees and 110 octane at 38 degrees, I have a 3200 stall as well.
 
I thought I had read up on programmable ignitions, but I've never used one, so I wanted to see if I understood the setup.

I didn't catch what you're running for a cam (I probably didn't ask), but that's quite a bit of compression. How did you arrive at your current timing curve?

Since you've been using 12 initial and 34/38 total without problems, I'd start there. I would say since you're using an OD trans (lockup converter?), it'll probably be loaded pretty heavy at low RPMs at times.

If it was my car...I'd start the upward curve a couple hundred RPM above idle and be all in by 3500. Road test and tweak the curve as desired. I would bet it would end up liking a few more degrees initial and a few less total...YMMV
 
I know my initial needs to be higher. I don't have bushings for my dizzy now, so I set the total where it likes it and the initial is what the initial is. With the new set up, I can get the proper initial, so I will play with that to get it correct. Here is what I have in the motor now, and I'll add the dyno specs as well.

Here is what I have:
1992 magnum block
scat 4" stroke crank
Scat forged i-beam rods
Diamond flat top pistons (11.8:1 compression)
total seal rings
Engine Pro main, rod, Cam bearings
Fluid damper
cloyes double roller timing set
Cometic head gaskets
Edelbrock performer rpm heads (gasket matched w/ light porting)
Smith bros pushrods
Comp 1.5 ratio shaft mount billet roller rockers
comp hydraulic roller lifters
Comp Cam
242/248 Dur@ .050, .3660/.3630 lift @ .050, 112° lobe sep. 549/544 gross valve lift
Comp valve springs, retainers, keepers, locators
ARP head studs
ARP bolts used throughout
melling hv oil pump
Edelbrock RPM Air Gap intake
MSD Pro Billet distributor
bronze dist gear
Taylor wires and looms
New ngk plugs
Holley 750dp mech secondary manual choke
Mopar MSD 6 Ignition box - going to MSD 6AL-2 programmable
Blaster2 Coil

View attachment Dyno specs (567x800).jpg
 
I've heard that you can get the initial timing by warming the engine up to operating temp, advance the timing a bit, let it idle a few minutes, shut it down, let it heat soak a couple minutes, and try turning it over. Advance the initial timing until you get kickback or it's labored turning over. Once it gets to that point, back off the timing a couple of degrees and that is now your initial timing.

I haven't had any success setting mine this way. It might be the MSDs I've been using, but I've had them up to 45+ degrees initial with no kickback using this method.

Here is a link to a similar question, post 3 from crackedback outlines a method using a vacuum gauge.

crackedback said:
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!
Click to expand...
 
There are video on youtube on how to set up that box using the software.
 
73Scamp318 said:
I've heard that you can get the initial timing by warming the engine up to operating temp, advance the timing a bit, let it idle a few minutes, shut it down, let it heat soak a couple minutes, and try turning it over. Advance the initial timing until you get kickback or it's labored turning over. Once it gets to that point, back off the timing a couple of degrees and that is now your initial timing.

I haven't had any success setting mine this way. It might be the MSDs I've been using, but I've had them up to 45+ degrees initial with no kickback using this method.

Here is a link to a similar question, post 3 from crackedback outlines a method using a vacuum gauge.
Click to expand...

This is a very bad method which is why it hasn't worked for you.

It reminds me of the guys that say turn it up till it pings and back it off a touch. Best is the one that says to do this while power braking the car.
 
I went to load the cd into my computer and play with the program. The drivers are corrupted and it can't run the drive. I uninstalled and reinstalled the drivers and still have problems. Damn computers! Gotta fix the drive before I can go any further.
 
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