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Discussion Starter #1 (Edited)
I just installed a 123 ignition last weekend and I'm playing with the curves. (Note that I have no vacuum advance.)
Here are my engine specs:
  • 2L with 5 speed gearbox
  • 2 x Weber 45 DCOE with Velocity stacks under a ITG JC50/S/65 Foam air filter
  • Spruell ceramic coated spaghetti headers
  • Cams: 11.2mm lift
  • CR: 10.5:1 Borgo Motronic Pistons
  • Standard valve sizes
  • Aluminum Flywheel (Spruell)
  • NGK B6ES Plugs
  • 123 Tune+-4-R-V-D Ignition
  • 2.25 in. exhaust with Magnaflow front and rear mufflers, and a small non-name middle tube muffler
  • 91 (RON+MON)/2 California Gasoline (lousy)

I started with a very "safe" curve (Test 1), and that ran fine and so today I tried a substantially more aggressive one (Test 2). Ran great!

I'm wondering where to go from here...
Call it done?
Make the curve steeper (more advance at lower rpm)?
Add a bit more total advance (closer to 40 degrees?)
 

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I would try getting all of the advance in by 4000 rpm and see if you can feel better mid range. If so try getting it all in by 3500 rpm. Listen carefully for pinging when you give it full throttle at 3000 rpm.
 

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Discussion Starter #3
I would try getting all of the advance in by 4000 rpm and see if you can feel better mid range. If so try getting it all in by 3500 rpm. Listen carefully for pinging when you give it full throttle at 3000 rpm.
4k is what I have in the second chart. So 3500 would be the next step.
Any comments on what to do below that? Do I need the flat area up to 900 rpm for startup, or should I start ramping up right from 500?
 

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It does not make much difference. My motor starts fine with 13 degrees static and stays at 13 before it ramps up to 34 degrees at 4000. You can get an unstable idle if the curve starts ramping below 1000 rpm, particularly if the ramp is steep.
 

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This is mine as set up on a Dyno for a fairly modified 1300 pushing 125bhp.

Mine needed some advance at lower than 500rpm to enable starting. But as the 123 only starts it’s curve at 500, you will see that the graph steps back slightly.

For the rest of the curve we played around with the curve extensively on the Dyno, about 4hours in total (including changes in main jets as well as choke Venturi sizes.

If you can, take the guess work out and go set it up on a Dyno.
 

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Also got this data saved that might help....

Second image is of the non-Bluetooth 123, the stock one with the preset curves..... which I knew wouldn’t suit me as very few are for a 1300.
 

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My newly rebuilt 2 liter engine is very similar to yours. My previous tune was pretty close to yours: advance was 32 degrees and both cams had a duration of about 254 @ .050 w/ a 12mm intake cam and 11.1 exhaust cam.. I thought the engine ran really good, although gas mileage was not good. What we're doing now is a bit different:

Ignition timing (MarelliPlex ignition) is "all in" @ 3000-3500rpm with a max advance of 36 degrees (we get 93 octane here in Texas).

Cams: Intake is a Centerline 11.1mm lift with 254 @ .050 duration. Exhaust is a stock 2 liter fuel-injection cam 9.6mm lift with 222 @ .050 duration.

This state of tune has made for a dramatically better performing motor. Throttle response is quicker, there's more torque available, gas mileage is improved, and overall power appears to be undiminished. Basically, my Super just feels better through the gears.
 

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Most motors will have a band of max ignition advance that will make maximum HP and the width of the band varies with a number of parameters. One of them is fuel octane. There will be a lower point below which the power starts to decline and a higher one that is usually determined by onset of detonation. Running a high compression engine with poor piston shape on low octane fuel will produce a narrow band and it may be advisable to run with a bit less advance to gain reliability at the cost of a little HP. Using a higher octane fuel will allow a greater safety margin and possibly sufficient advance to get maximum HP from the motor.

Cam design has a significant influence on the width of the power band. Jim Steck is rebuilding a race motor for one of his clients. He described it as a Spruell motor. He dyno'd it before the rebuild and then again with just a change of exhaust cam. The cam that was in it was a long duration cam and the second one was an RJ785. The peak power of the two runs was very similar but the 785 made almost 25 HP more at 5000 rpm.
 

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Discussion Starter #9
Well, I have done some more testing.
(I should note, I had been getting some pinging with 33 degrees advance and my mechanical distributor. So one of my goals with the 123 has been to see if I can adjust the curve to avoid that. Unfortunately, I don't know what the actual curve of that distributor was... but I do suspect it was very steep.)

The Test 2 curve from earlier was running great, but I wanted to try and get to full advance earlier.

Test 3: I went to full advance at 3000RPM and used a generally much steeper curve. 28° at 2000 RPM. That seemed to work on my short test course and so...

Test 4: Full advance (33°) at 2500RPM. I also did away with the flat at idle so I was at about 15° at 1500 RPM and 28° at 2000 RPM. (This curve was recommended by Stewart at APC. I probably wouldn't have gone this far without his prodding!)

Test 4 went OK! Idle was a bit faster. I was listening very carefully for pinging... but that was a tough task, as I don't spend much time between idle and 3000RPM. I did run it up a hill in a higher gear, floored and it was OK in today's weather.

I'll have to drive some more with Test 4. It seems great, but I'm not sure there is much advantage over Test 3, as I don't spend much time below 3000 rpm. But if the engine will do it without pinging, in all weather with the variations in pump gas, that will be cool.

I'm tempted to move to 34 or 35 degrees of total advance next...
 

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Are you all setting TDC on the 123 with a strobe against the pulley, or just using the built in green lamps/leds?

I only ask as I’m still confused about initial and static advance even settings.
My Bluetooth 123 runs great but I’m still pfaffing with curves
 

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Are you all setting TDC on the 123 with a strobe against the pulley, or just using the built in green lamps/leds?

I only ask as I’m still confused about initial and static advance even settings.
My Bluetooth 123 runs great but I’m still pfaffing with curves
For the Tune version you do the initial distributor body setup with the green LED. Then once the car is running you should do a one-time adjustment using a timing light at idle to get it dialed in to exact TDC. After that you lock it down and shouldn't need to touch it again: all further adjustments are done in the software.

It's a little different conceptually than the non-Tune version. With the non-Tune version you set the static timing by rotating the distributor, and then the centrifugal advance is whatever curve you select. On the Tune version you just program a curve and whatever you program is the total advance at that RPM.

e.g.: my curve starts at 6 deg advance at 500-1000 RPM (so that's sort of the "static timing") and goes up to 36 max advance at ~4250. After doing the LED thing I set my timing light to 6 degrees advance, and then with the car idling tweaked the distributor slightly until the timing mark lined up exactly with TDC. It was only off by about a degree after doing the LED adjustment, IIRC.
 

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Discussion Starter #12
Are you all setting TDC on the 123 with a strobe against the pulley, or just using the built in green lamps/leds?
I only ask as I’m still confused about initial and static advance even settings.
My Bluetooth 123 runs great but I’m still pfaffing with curves
People do use the word "static" advance in different ways.

First I confirmed the TDC mark on the crankshaft pully was correct by using a dial gauge and finding TDC through the #1 spark plug hole.
I installed the 123 with the built in green LED, but then confirmed the TDC with a timing light. BE SURE YOU USE THE TDC AT THE TOP OF THE COMPRESSION STROKE!
Then,
Say your initial advance is 8 degrees between 500 and 1000 rpm: With a digital timing light, you should be able to set it to 8 degrees, rev the engine to 700 rpm and see it flash on the TDC mark on the crankshaft pulley. That would indicate the ignition is firing 8 degrees before TDC.
 

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Discussion Starter #13
I only ask as I’m still confused about initial and static advance even settings.
A bit more on this. IMO:
"Static timing" is any setting done with the engine off: not running. This isn't necessarily related to how much advance is being set or measured. It just means you are measuring with the engine off. For instance, on some vehicles you can (and people do) force the ignition to a fully advanced setting, and then checking the setting. Some even do this with cellophane inserted between the points and using that to tell when the cellophane is released by the points opening while manually rotating the engine.
On the other hand, many just commonly consider "static" advance or "initial" advance to be the advance that the engine has at 0 RPM with the advance mechanism in it's base position (the mechanical or electronic mechanism hasn't advanced the the ignition forward from the base setting).

So, relative to the 123: you can electronically set the advance setting starting at 500 RPM. But you can also set the rotation of the distributor as you see fit. Sensibly, most set the distributor so when the electronic advance is set to 0, the ignition is at TDC. But you could set it otherwise, and just add that extra advance to the electronic setting.
 

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My discussion/question etc., is really just this.

Knowing that the cars will want a certain amount of advance (6-13deg) at idle to run, with increasing advance based upon RPM/load/engine type and build. How do you all baseline or calibrate your curve?

My thinking is the 123 needs to be installed, roughly set to TDC with the green lamps and then checked/calibrated with a strobe. Then zero degrees on the curve (at any RPM) will be TDC and any degree of advance that the curve requests of the dizzy will be correct.

That’s how I set up my 123.
All I have to do now is determine the best curve.

It’s the “what” makes the best curve info that I lack.
I find that my car will idle fastest with 15-25deg advance at 800rpm
I suspect this is too much when load is applied to the engine

I can also run at 45deg advance from 3000rpm.. but will get pinging (if that’s what it is.. I’ve never had it explained to me correctly)

Just talking outloud

I’ve
 

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Your centrifugal curve is quite steep at idle rpm and you may find that it does not want to settle at 1000 rpm and instead slowly speed up.
 

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I encountered a similar pinging problem with my first 2 liter hot-rod build. In the mid-to-late 80's the best pump gas we could get in Texas was 91 octane. At the time I was running 10.4 Borgos with cams that were similar to what we're talking about here. I was using my trusty, re-curved MarelliPlex that I'm now running on my new motor. Here's a couple of factoids from that period.

First a definition of terms: "Knocking is more commonly known as pinging. But it differs somewhat from detonation. Knocking / pinging is caused by the peak cylinder pressure event coming too early because the flame front from the spark plug initiated too soon." --- from the internet.

Especially in 100 degree Texas summer weather, my high-compression motor would ping under even a light load. At the time, I had recently discovered David Vizard's various books on engine building and was reading everything of his that I could find. In one of this tuning books Vizard mentioned that a common characteristic of Otto cycle engines is a knock/pinging event at about 2400 rpm. With my "all in at 3k" advance curve this is exactly what I was experiencing. I surmised that that I was experiencing the flame front problem described above.

Vizard was also enthusiastic about MSD CD ignitions which, as we know, were designed to have longer firing events at lower speeds. I put two and two together and decided to see if the MSD's multi-firing over about 30 crankshaft degrees design would reduce or eliminate the pinging I was getting. To shorten a long story, the experiment worked. With the MSD installed, my 10.4 (actually about .5 or .6) was completely eliminated. It was really surprising to drive in 100 degree stop and go traffic and not experience pinging. Even with the 91 octane gas, my hot-rod 2 liter was a smooth as could be. So what was the MSD ignition doing? It appears that the multi-firing design was doing a better job of controlling the ignition evet, despite the limitations of the 91 octane fuel.

The culprit, of course, was the crappy 91 octane gas which was all that was available at the time. With my newly built 2 liter and 93 octane gas, I'm comfortable running the same MarelliPlex and no MSD.
 

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Discussion Starter #17
Your centrifugal curve is quite steep at idle rpm and you may find that it does not want to settle at 1000 rpm and instead slowly speed up.
I have some concerns there, but so far the idle is fine. I'll see how it drives and starts over the next couple weekends.
 

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Discussion Starter #18 (Edited)
It’s the “what” makes the best curve info that I lack.
I find that my car will idle fastest with 15-25deg advance at 800rpm
I suspect this is too much when load is applied to the engine
Setting up for fastest idle when warm may not result in easy starting when cold.
In my opinion, the idea is to retard the ignition for easy starting. We all talk about advancing the ignition... but really it is often helpful to think of things in the reverse. Consider the full advance target to be where you get best power at your mid and high RPM. That is why it is best to tune on the dyno, as over advancing can actual result in the power falling. After you have the mid and high RPM figured out, it is about making the car easy to start when cold and idle and to rev cleanly up the scale.


I can also run at 45deg advance from 3000rpm.. but will get pinging (if that’s what it is.. I’ve never had it explained to me correctly)
Pinging is a poor and vague term. And it is best to know many misuse the terms, so you often have to deduce what they mean from the context. Best to google: pinging, knock, preignition and detonation. Generally, when I say pinging, I am describing a sound I hear, a bell like rattle.
In my case the pinging comes for too much advance for the relatively low octane fuel. Either reducing the advance or increasing the octane solves it. That likely means that with the excessive advance the fuel burns too early and quickly, while the piston is still rising.
 

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Pinging is detonation if it can be eliminated by less spark advance or higher octane gas. Mild detonation is not always destructive but severe detonation can damage things quickly.
 

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Discussion Starter #20
Update.
I had a chance to drive my test loop today that has a couple good hills and on one of the steeps I found the engine pinging between 2500 - 3000 RPM.
I ended up with this new curve, with that area softened. I lowered the advance a bit at 2000 RPM and and pushed full advance out to 3500 RPM. But I need a bunch more testing.
I do like the steep early part of the curve, the car runs very nicely down low. No problems so far without the flat spot for idle. It idles right at 1000 RPM, and I am sure I could adjust the idle speed down at the carbs( as I was idling at 700 RPM with my 8 degree flat spot from my earliest tests).
Oh, and I need to tape up a few things that rattle in my car. When I am listening for pinging, every rattle startles me. My passenger seat belt and seat back, when empty, produce a bunch of rattles that can easily be mistaken for pining if I'm not paying attention!
 

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