Distributor rebuild or 123

[knapmann]

My distributor may need rebuilding (not sure yet) but I suspect a rebuild will cost more than buying a brand new 123 ignition distributor (£300) with fully adjustable ignition advance no points etc etc. Lots of people in my former BMW 2002 community use these and love them, and I know other people who have them and think they are great as well. Does anyone have any 911 experience?

Alternatively are there any go-to UK based distributor rebuilding places?

Neil

[Jonny Hart]

Another option is to lock the distributor weights and use one of our CDI+ units to control the timing. The ‘69S is the model that sees the most gain from our system.

[knapmann]

Another option is to lock the distributor weights and use one of our CDI+ units to control the timing. The ‘69S is the model that sees the most gain from our system.

Ive read a few people who say the 2.0S needs accurate timing. Ive also read this thread where the seemingly knowledgeable person who rebuilds distributors commercially says that "The 69S distributor. It carries the same curve as a 2.2 but is completely inappropriate for the motor. Too aggressive. A 67S curve would be better." he then goes on to say.... "One model specifically that will benefit is the 69S as it has too much compression and too aggressive of a curve. That one would get a completely custom curve. Something that is not possible with the original dizzy." Do you have any knowledge about this i.e. running a different advance to factory on the 69S?

https://www.early911sregistry.org/forum ... stributors

[Jonny Hart]

^ Yes, in depth. Pretty much all the early performance engines can take way more advance in the midrange which yields lots of power. It’s a one way outward journey for a mechanical weight whereas an electronic system can apply greater advance in the mid range and bring the advance down again at high RPM to avoid detonation.

[inaglasshouse]

^ Yes, in depth. Pretty much all the early performance engines can take way more advance in the midrange which yields lots of power. It’s a one way outward journey for a mechanical weight whereas an electronic system can apply greater advance in the mid range and bring the advance down again at high RPM to avoid detonation.

This. Based on first-hand experience on my 69S with Jonny's CDI+. Midrange advance changes make a very noticeable difference.
Cam timing also said to be important on these, but less easy to fiddle with...

[911hillclimber]

How are these 'electronic' advance curves set?

Can you get a pre-programmed box for a stock 3.2 currently using a 2.7 Carrera dist and points?
Some of this was discussed on my engine mod thread a few weeks back.

My 3.2 is in my hillclimb car that works WOT 90+% of the time, but a gutsy pull on WOT from , say, 2500 rpm to max red line is how it is driven (on carbs) so wondering if there is much to be gained in Jonnie's 'box' in my application, totally non-road going.

[PeterK]

Take a look at Jonny's Classic Retrofit website, and download the user manual for the CDI+ box.

By dialing in extra advance as a base line, the electrickery can then delay spark to give whatever advance you need at each and any point in the rev range. The advance curve is programmable, so start with a 'stock curve' to prove everything is working as before, then optimise it (on a rolling road).

While you can add or subtract advance from whatever the dizzie is giving, my preference is to lock the dizie so that it provides no advance, then the only advance is coming from the electrickery. AFAIK, then you can add whatever curve you want to any dizzie.

[911hillclimber]

Ah, ok, I was hoping to avoid the rollers!
Thanks Peter.

[PeterK]

Rollers are safest, best and p[robably quickest, but driving it, tweaking it and driving it again will do Graham

[911hillclimber]

Many of the runs on the hills are much shorter than 1 minute and about 6 gear changes, not much time to assess the car's performance, so the rollers are the only alternative and I'm sure will add a high cost to optimise, but that goes for anything really.

The way we as a country are going next year's motorsport could be off to a weak start, not worth doing in my case, but feeling naffed off anyway.