TheSamba.com :: View topic - Question about 123Ignition Curve/Map settings

Thu Aug 18, 2022 2:34 pm

Hi Folks,

If anyone here is using the 123Ignition...

In my 71' Westy with a 1776, I installed a 123ignition system TUNE+-4-R-V-V with Bluetooth found here: https://123ignition.com/product/tuneplus-4-r-v-v/

Using the original curve diagram...

I created the following map:

It runs (haven't driven yet) pretty well with only hesitation at idle (900 RPM).

Please note that the 123Ignition uses crankshaft values as opposed to centrifugal values (hence doubled).

Since this is now a single vacuum advance (and compensating for a retard in the MAP curve). Do you think I should static time to 5deg ATDC (as the original 211-905-205Q) or more like a SVA (0deg or 7.5 BTDC)?

Thu Aug 18, 2022 2:58 pm

From old volks. See bottom line. The retard was a smog thing. It relied on non-ported vacuum being overcome by ported vacuum off idle in 34-pict3 carb.

Bus & Pickup 1971 * 1600

Distributor: VW 211-905-205Q, Bosch 0231 167 055 or 211-905-205S, 0231 180 001 > 043-905-205D, 0231 176 033
Can Use: VW 043-905-205D, Bosch 0231 176 033, 113-905-205AH, 0231 167 053
Points: 01 011
Points Replacement Plate Assy: VW 311-905-227A, Bosch 1237 110 064
Condensor: 02 054
Rotor: 04 033
Note: 205S/001 Distributors originally equipped with 04 021 Speed Limiting Rotor (4500rpm)
Dust Cover: 039-905-241, Bosch 1230 500 139 > 1230 500 147
Cap: 03 010
Distributor Cap Clip: 034-905-265, Bosch 1231 251 033
Parts Kit (Shims, Washers & Hardware): 059-998-211, Bosch 1237 010 007
Coil: 00 015 (Blue Coil: 00 012)
Vacuum Can: 07 092
Ignition Wires: 09 001
Spark Plug: W8AC
Timing Set At:: 5deg ATDC @ 800-950rpm w/strobe, vacuum hose(s) connected
Advance/Retard Range: Vacuum: 2-5deg Adv, 11-13deg Ret; Centrifugal: 12-16deg @ 2200rpm, 22-25deg @ 3800rpm

Thu Aug 18, 2022 5:45 pm

ChipWrecked wrote: Hi Folks,

If anyone here is using the 123Ignition...

Since this is now a single vacuum advance (and compensating for a retard in the MAP curve). Do you think I should static time to 5deg ATDC (as the original 211-905-205Q) or more like a SVA (0deg or 7.5 BTDC)?
I don't understand the MAP curve.

Thu Aug 18, 2022 6:05 pm

Keep in mind on those original curve diagrams....
The degrees on the left are distributor degrees, double for crank degrees.
The rpms on the bottom are distributor rpms, double for engine rpm.

Thu Aug 18, 2022 6:14 pm

Isn't that the most expensive one that allows you to program the curve into your unit? If so that's what you need to do and you will get the exact curve you program.

The curve you posted has three parts. One part is the mechanical advance. The other two parts are the vacuum advance (one for retard and one for advance).

Fri Aug 19, 2022 5:17 pm

If you are setting the max mechanical advance at 25*, the idle timing should be 5* BTDC to avoid going over 30* total mechanical. If you’re not subject to emissions testing, you can even keep the mechanical limit at 30* and bump the idle/baseline timing to 10* for better throttle response.

I personally set all the sub-1,000rpm values to 7-10* and max to 30*. That way you don’t have to do any mental math.

Vacuum curves are a different animal, and are often engine-dependent. Your vacuum curve looks too steep, though in the ballpark as far as raw numbers go.

Robbie

Fri Aug 19, 2022 5:28 pm

the factory distributor thinks like this.

I would like to be around 7 1/2 degrees BTDC at idle, maybe 8.

When I am at idle, because of this stupid retard can I am maybe 7 1/2 to 8 degrees minus 11 - 13 which makes me spark at about 5 ATDC. But as soon as someone steps on the gas that stupid retard can leaves me alone and my spark is around 7 1/2 to 8 BTDC degrees.

When someone does step on the gas to where my engine RPM gets up to about 1050 - 1100 RPM then my centrifugal timing advances an additional 22 - 25 degrees by 3800 RPM so 7 1/2 - 8 plus 22 - 25 is about 30 to 32.5 degrees or so.

My vacuum can does its own thing based on how much vacuum the engine is pulling. It usually only adds more advance when I am in lite cruise mode and not on the throttle very heavy.

To get the proper advance, ignore the 5 retard. Set the initial timing at idle to 7 1/2 to 8 BTDC and the advance to 22 - 22 1/2 max at 3800 RPM. That will give you about 30 degrees max advance. 2 less than VW designed but the heads will be cooler with the crappy fuels we have now.

Sat Aug 20, 2022 3:29 pm

Thank you all for the responses and the thoughtful comments.

I took the bus out for a 50 mile ride today. It was timed using the stock 5* ATDC. Throttle response at idle to go was "okay" but the rest of the RPMs were very smooth, no pinging, very responsive.

blue72beetle wrote: Keep in mind on those original curve diagrams....
The degrees on the left are distributor degrees, double for crank degrees.
The rpms on the bottom are distributor rpms, double for engine rpm.

Yes, correct... you'll see that the centrifugal values on the curve settings were doubled to compensate for the needed crankshaft values.

airschooled wrote: If you are setting the max mechanical advance at 25*, the idle timing should be 5* BTDC to avoid going over 30* total mechanical. If you’re not subject to emissions testing, you can even keep the mechanical limit at 30* and bump the idle/baseline timing to 10* for better throttle response.

Robbie

Thank you Robbie, That makes sense, I'll retime to 7.5*BTDC and compare to the previous timing.

SGKent wrote:
To get the proper advance, ignore the 5 retard. Set the initial timing at idle to 7 1/2 to 8 BTDC and the advance to 22 - 22 1/2 max at 3800 RPM. That will give you about 30 degrees max advance. 2 less than VW designed but the heads will be cooler with the crappy fuels we have now.

Thank you (and your distributor's thoughts) also, as this illustrates nicely how to approach this.

Sat Aug 20, 2022 3:35 pm

The stock distributor, 211 905 205 Q works likes this:

With the engine at idle and the vacuum lines connected you will need to time the engine at 5ATDC. This is because the retard side of the vacuum retards the advance as shown in the advance curve.

You can also time it at 7.5 degrees with the vacuum hoses disconnected. When you connect the hose it should go to 5 ATDC.

You'll have to figure out how the 123 handles all of this to make sure you set the timing correctly.