DDK - Die Deutschen Klassiker

The 123 has the correct curve set via a rotary switch if you buy the non programmable one. The programmable one you can down load the curves and load them.
Jonnys box is a CDI with a programmable curve. Very clever piece of kit. It uses your distributor which you lock the advance in some way. You would need to replace the coil for a CDI coil, (Jonny has a coil in development if not in production), and make up a loom for the wiring. We have had many a conversation over adding one to a 912 and seeing what difference it would make. You would need to program the curve and rev limiter. Two sparks per firing though and a higher voltage at the coil means a bigger stronger spark at the spark plug.

I used the pre-programmed, 123 advance curve for the SC/912 engine and it works perfectly.

What was your previous set up Ashley, original 022/031 or an 050 maybe? And have you noticed any difference in performance since fitting the 123 or is it just the convenience of the plug and play factor that makes it a worthwhile upgrade?

Thanks for the breakdown Sean, Johnny’s cdi set up sounds very interesting. With two sparks per stroke and a higher voltage I wonder how well it compares to a twin spark setup?

Timo wrote:What was your previous set up Ashley, original 022/031 or an 050 maybe? And have you noticed any difference in performance since fitting the 123 or is it just the convenience of the plug and play factor that makes it a worthwhile upgrade?

Not really any noticeable difference because I’d overhauled the standard distributor before, but there was on the Healey because the points kept closing up and if I set the static timing correctly, I had too much advance, even with a new distributor. So, as I was off to France in the Porsche, I thought it wise to fit a 123 and avoid issues.

I’m still using the original coil, which probably has a much lower output than current offerings.

My view is that carburettors are enough trouble on their own without having to keep setting points and checking timing as well.

There is a big price difference between a 123 distributor and Jonny’s CDI box and coil, I would want to understand the benefits of the CDI over the 123 before committing - twin spark sounds interesting, though. Have you collected your 912, Anta?

I’m pretty sure changing to electronic ignition will give you a better spark, but also sure that you won’t notice a performance improvement if your old system is correctly adjusted.

The benefit is that you can fit and forget it, not entirely because if your plug leads go open circuit, as they do with age, it’ll cause a failure of the electronics, so fit new plug leads when you make the change.

Points close up and wear, ATD units get sticky and bearings wear, so you’re constantly maintaining an old fashioned distributor and not an electronic one.

I've been using a 123 distributor on my 912 for a few years now and I'm really pleased with it. Once set up you never need to touch it!
Rob

robs912 wrote:I've been using a 123 distributor on my 912 for a few years now and I'm really pleased with it. Once set up you never need to touch it!
Rob

Just remember to replace the plug leads from time to time, or just check their resistance is correct. This applies to all electronic ignition.

I second what Anta said - I used the 123 bluetooth on my alfa and love it. All that and having a known-accurate tachometer, GPS speedometer and volt meter in the bluetooth 123's ap is really excellent. And to be certain you don't have to connect to the ap once you have your curve set. You can simply treat it as set and forget.

Timo wrote:Does the 123 come with the correct curve pre set for a 356/912 or do you have to set it up yourself?

Also what is the difference between a 123 and Johnny’s cdi type setup? I’m not familiar with the way a cdi works.

The 123 comes in various forms but if your car has a standard engine you can buy one preprogrammed for it. You really don’t want one you have to program unless you’re prepared to shell out for a rolling road to set it optimally and because the engine is tuned up/

I have to agree with Ashley. If you have a big bore with a standardish cam then the 022 curve will be good. However, if you like to play and have a friendly RR

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Ok thanks guys.

Mine has 1720 b&ps and Weber 40idf carbs, no idea on the internals but fairly confident it’s stock ish. It’s a Harry pellow engine, I’ve heard that he tended to use lower compression due to the poor quality US fuel, but often used his own cam which brought the power back to normal levels. Mine rr’d at 99bhp and around 115ft ibs torque so it’s not far from standard.

It’s currently running an 050 so hopefully a 123 with standard curve would be as good if not slightly better.

Mine’s a 1720cc with an SC crank and I presume a 912 cam and runs extremely well right through the range using standard 356/912 advance curve.

I have twin 40mm Solexes with 0.60mm pilot jets and 120 mains

Another vote for the 123 dizzy. Had mine for 2 years and not touched it since. Was experiencing some very odd running issues, which were hard to diagnose but likely to be related to my 050, the recommendation to swap to 123 sorted everything out. Well worth the money, and not heard of any issues with these elsewhere.

Previously I ran Petronix EI in my 050 dizzy, but had 3 of these over the past 13 years and they do tend to give up eventually.

My engine is 1720 with 40 idfs, performance and power is very smooth.