Single distributor electronic ignition wiring order

Hi everyone,

Although this could warrant a whole separate post as that’s the next issue I need to tackle, I have been having big corrosion issues since installing a 123ignition single distributor ignition module on my Ferrari 308GTB, which I believe could come from a bad seal bringing oil mist into the cap.
In order to clean the cap, I decided to take all the plug leads off it without really looking at how they had been wired by the previous person before (very smart I know).

Now I am a little unsure on how to wire it back. The rotor has two brass arms and the distributor cap is numbered in the following way: 1-8-3-6-4-5-2-7 (I put a diagram picture as well of the way it’s numbered)

is this numbering the correct wiring for this set up or is it a universal molding?
As the correct firing order for the car is 1-5-3-7-4-8-2-6…

Should i just ignore the numbering completely on the cap and wire it from where TDC points at in the firing order to spec?

Or, Could it be that, as this rotor has 2 contacts, it fires on both in turns, meaning i should follow the number molded on the dizzy cap?

All help is much appreciated!

Kind regards,

Fred

Image Unavailable, Please Login Image Unavailable, Please Login

 

Thanks for the clarification! The dual-plane rotor did indeed confuse me a bit, if I’m honest. I tried to make sense of it at first but didn’t realize it was skipping across, so the order didn’t add up in my mind. Now it does!

Regarding the 123ignition, I’ve been thinking for a while about starting a separate thread on the subject. For now, though, I’ve decided to hold off a little longer, because my honest review so far wouldn’t be the best publicity for them. I’m hoping my opinion might still change…

I started with the module about 18 months ago, on the recommendation of my mechanic, replacing the old MSD unit I had. At around $4,000 a piece, I was hesitant at first. After installing it, I was unlucky — the unit failed within the first week due to a manufacturing defect. They replaced it under warranty, it didn't bother me too much as that can happen with electronics (especially with parts that aren’t mass-produced).

However, since then the car has never really run perfectly, and I’ve been dealing with issues non-stop. First, the distributor cap failed due to carbon tracking; the manufacturer told me it was also a production defect. My second distributor cap developed severe white/green oxidation on all the contacts, which I constantly had to sand down to avoid the car misfiring like crazy. That cap finally gave in when the carbon brush inside corroded beyond repair. I then bought a third cap, which lasted just four months before one of the two coil terminals on it corroded so badly it ate through both the lead and the coil itself.

I’m now on my fourth cap in 18 months. At this point I’ve realized that, instead of simply swapping caps every couple of months, I need to find out what’s really causing the issue. The car is always stored indoors, never driven in the rain, and regularly run up to temperature, so the problem isn’t environmental. I strongly suspect a sealing issue somewhere inside the unit blowing condensation or oil mist into the unit and into the cap. Each time the corrosion started, I’d experience the same symptoms you described — the car running rough at higher RPMs, usually always on an exact range. Did you check your cap and terminals for signs of white/green deposits? In your case, it could also maybe just be the advance curve you set not being the correct one? Just thinking off the top of my head here.

The main issue with this gear is, good luck testing it yourself to find a small intermittent fault...

I’ll be contacting them this week in the hope of getting some real assistance, but as you can imagine, up to now the experience has me regretting not simply going back to double-points distributors and keeping the car fully original. I'm hoping they can test the unit on a test bench and figure out what's going on with it.

 

I see, I first ran the cap provided with the module, then one from OKP germany which are about 250USD a piece, that's still less than the OEM marelli ones though!

My car is a 76 US spec, one of the first 1000 steel bodies I believe.

Re the unit, I purchased it as a complete unit with a new body milled to match the OEM one. I didn't purchase it through them directly but through one of their distributors. Here's a picture of what I'm working with:


Something very strange did happen however. Before writing this thread, I had wired the car in a hurry following the firing order clockwise (so, incorrectly). The car was backfiring like crazy but did start and would stall after a while, with very low idle (450-500). This morning after reading your reply and getting help also from the one and only ferrarichat hero Steve Magnusson, I wired it again following the diagram shown here. Now the car doesn't start anymore... checked the plugs, coils, everything sparks, used starter fluid in the carbs, which just ignites directly in the car sending big flames out of them. But no way to start the car. I'm going to rewire it like before and see if that still works at least to start it...

Any idea where I could have gone wrong? I feel like I made a mistake somewhere... but just can't wrap my head around it.

 

Image Unavailable, Please Login

 

Thanks again for all the help and wisdom here. I had been discussing this in parallel with steve magnusson on here as he had seen my thread. Just like you just mentioned, he told me that I should go back to the first step, TDC 1.

I tried to rewire the distributor cap again like I would with a single rotor one, just doing the firing order clockwise ignoring the numbers on the cap. The car fired up but ran rough again, at very low RPM. I then swapped again following the diagram showed here, following the numbers on the cap and, nothing, not a single pop or bang and no start...And then it hit me... the rotor was 180° upside down and had been set up at #1 up but on the exhaust stroke... This meant that when wired incorrectly following the firing order like a single rotor, it fired once out of 2 times, even with the rotor upside down, explained the start and half idle, but once wired correctly, it was completely off not even firing a single plug in the correct order...

Swapped the rotor around and... tada!

Thank you so much again for helping me through this one which was a real headache... even if it was just a simple fix at the end.

I'll happily keep you updated on how long my new cap survives and if it corrodes again.