365GTC/4 Ignition issue

Evening All.....I own 14957. I've developed and intermittent ignition issue. At times the drivers side bank is totally dead. She'll run on 6 cylinders, but not well. My car has 2 distributors. I did the AEC103 upgrade several years ago and all was well. The problem started after a winter of slumber. When the drivers bank is dead, there is zero output from that side's coil. I put a timing light on the coil lead going to the cap....Nothing. The ignition boxes have a full 12volts, all wire connections have been checked and are good. I've replaced the coils as well. Still no dice. The black wire from the ignition box goes to the Tach drive post on the distributor. I noticed that each distributor has two posts. Are they both tach drives. I'm wondering it the points are sticking in the closed position?? Does anyone have any photos of the insides of these distributors??? There's just not much the ignition on these cars. What am I missing??

 

Nothing. The points could also be always open (or broken). If you take the dist caps off, you should be able to just visually observe the points motion in each during starter motor cranking to confirm if things look reasonable or not (and compare the working one to the non-working one). Would also give you a chance to inspect the carbon button and distributor rotor in both.

 

As a simple attempt, I would put a new carbon button, and check how strong the spring is.

Depending on where you live, you could be next to someone that has a Sun distributor tester with the Magneti Marelli adapter. There is also a specialist called North that can fix these.

 

Good day Raemin,

Given that he placed a timing light on the coil output to the cap, the carbon button/spring or lack thereof would not cause this issue... unless the button, etc was shorted to ground... which is not overly likely... as indications of this would be quite evident.

Since the poster stated "I did the AEC103 upgrade", I am unsure what this all entails and it makes it challenging to provide direction other than checking the points, etc... and if anything once could manually trigger the point wiring and note if the AEC103 fires or not. However, this should be done cautiously, as the resulting voltages generated are significant and can certainly give one a "bite" if zapped... and depending upon one's health condition, could cause serious issues (e.g. cardiac dysfunction).

Cheers,

Sam

 

Good day geffen365gtc/4,

Although I do not have a picture, I do have a diagram of the distributor's guts that might be of interest.

Cheers,

Sam

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Since the OP mentioned having "each distributor", I'd guess that he has a dual-distributor US version 365GTC4, but the picture would be very similar -- just fewer point sets in each (but neither the SPC nor OMs are very clear about this).

 

If it has modern era Marelli points I have has several experiences of the tungsten faces simply falling off. One of the reasons I am very reluctant to work on cars with real distributors. Quality parts are no more.

 

"boosted" points do need a clean cut in order not to play havoc with the "booster". The boosted signal is also hard on the distributor cap.

If the AEC103s work as ignition boosters, it should be possible to disconnect them and use "emergency" (i.e regular) coils. This would let you know if the distributor is faulty.

If the engine works up to 4000rpm with the emergency coil, then it's either the coil or the dinoplex.

Swaping the coil(s) and dinoplex(s) could also help diagnose these two components.

 

I've swapped the boxes side to side. The problem stays on the drivers side. Both coils are new.

 

Yes, my car is dual-distributor. I've starting to think the issues is whatever in the distributor triggers the coil to fire.

 

My car has no anti-hop device and there is a 1.8 ohm resistor on each coil. The AEC103 has 4 wires. Green...Obviously ground. Black......Tach drive post on distributor. Red.....12v source. Yellow....Coil negative. All as per the AEC103 spec-sheet.

 

If you also no longer have the Microswitch = that would be a clear sign that your R2 points have been removed (or disabled), and you would only have the R1 points in each distributor. Not really a serious operational issue (and often done to the carbed US 308s that also have an R1/R2 set-up), and makes things more simple to fix, but does make the carb adjustments a little more sensitive at idle as it will have more ignition advance at idle.

 

Good day,

Were your AEC103's upgraded in the sense that the original internals were replaced with modern electronics? I ask, as your wiring colors and connections do not seem to match up the AEC104 and C4 wiring diagrams I found. I am not saying that this is the issue, but it does make testing procedures, etc difficult if one is not clear on how your system has been setup.

Cheers,

Sam

 

The AEC103 kit that I installed is the one sold by Ferrari Parts Exchange. I understand that the wiring colors might not match the factory looms, but the car ran perfectly with this set-up for many years.

 

After spending a fortune on modern dry coil, I am now hunting in the junkyards for original coils... So don't take your new coil reliability for granted.

Also which coil are you using? Depending on how your ignition was upgraded, the use of a coil with a ballast resistor might not be the best: remember that these coils are in theory more beefy (when cranking) , but the resistor slows down the recharging process which can be an issue at high rpm (when the coill does not have time to fully recharge between each spark).

Bosch modules for instance do have a feature that allows to not oversaturate the coil at low rpm, so you can use low ohm coils without ballast.

All in all it would make sense to ask your supplier with the sort of "gut" that was retrofited (dwell management, oversaturation management) , and the type of coil that were normally used with these modules: the fact that the module is compatible with the AEC103 coil does not mean its the best coil for this application.

Some module are not reliable in the long term (@samsaprunoff has some experience on Pertronix, other members on MSD). So knowing what was installed does help.

Last but not least: did you clean the distributor and lube its wick? A sticky arm could somehow work at low rpm, but fail to recharge the coil at higher rpm.

 

Good day,

I understand that, however, the wiring between the module and the other parts appears to be different...

If it worked before, then great. However, then why not simply simulate the breaker points and see if spark is generated. This would be trivial to do... but like I said before, you better be careful and know how to direct the resulting high voltage spark, as if not you can get one hell of a zap and depending upon your health condition, could cause a cardiac arrhythmia/dysfunction.

Cheers,

Sam

 

Good day Raemin,

Old coils can have issues despite what they physically "look" like. The coil's internal isolation material/fluid does break down over time and in doing so looses its ability to isolate the high voltage from shorting internally.

As for the off the shelf modules...I have experiences with both Pertronix and MSD and found that Pertronix's electronic trigger input to be somewhat variable depending upon when the module was manufactured. MSD has been far more consistent. Secondly, Pertronix's tech support is absolutely dismal for more technical details. MSD's tech support, on the other hand, has been fantastic. If MSD's initial tech support person could not answer the question, it gets elevated to a more senior support agent and/or someone within their engineering department. Given MSD's tech support, I typically go with MSD... I would rather support firm's that actually support their customers.

Cheers,

Sam

 

Good day,

I was curious if there is any correlation to engine temperature? Does the issue present when the engine is both cold and hot, or only with hot, etc? At times when electronics are on their way out, they can exhibit problems when they get hot (thermal shutdown).

Cheers,

Sam

 

It happens both when dead cold and 195 degrees. A local trusted mechanic thinks that the points are going to ground thru the post that goes thru the side of the distributor housing.

 

That would be easy to spot (item 7 in the diagram posted by sam).

This being said, the bulk of the load is assumed by the dinoplex, so the breaker are not supposed to wear fast.

Also it seems strange that the whole bank is lost. I would not expect the breakers to quit simultaneously.

In any case, servicing the distributor could be a good idea: even if the distributor is not the root cause of your issue, if it was not services for long, the timing and the dwell are now probably off.

 

Have you tried switching the coils?

 

I've replaced bot coils.

 

Replacing the coil is not the same as switching coils.

So far we don't know which ignition modules are actually in the car (as these are not original dinoplex), which coils are in, when the points were last replaced or even if the distributor was lubed.

As a rough guess, I would say :

1) (presumably) stock coils & ballast are not matched to the modern ignition module. This should not be a major issue unless the ballast are bypassed. In this case the car should run for 5~20 minutes until the coils get hot and quit. A coil that is hot to the touch is to be considered suspicious, swapping it could help confirm the issue. Also old-school Bosch coils were more tolerant to so-so implemented ignition boosters, whereas the modern one not so much.

2) The points may need to be replaced. Normally the dinoplex takes the bulk of the load, so the points themselves do not wear. However the point's arm that slides over the cams of the rotating shaft does wear, and can even wear pretty fast if the distributor wick was not lubed regularly. On a boosted ignition, it's the arm that wears not the point itself.

3) Points could also be very dirty : the high amp that normally goes through the points does provide some self cleaning (arcing burns dust and residues), unfortunately when boosted, the amp-draw is so small that the self-cleaning process is lost. A properly designed booster should include some voltage supply and a small load resistor so as to allow for this self cleaning. If the electronic guts that were used as a substitute for the dinoplex are regular ignition module converted as a booster, depending on how the conversion was made, the self-cleaning feature may or may not have been implemented. In this case cleaning and lubing the distributor regularly is mandatory.

Unless the issue is related to the coil, given how troublesome it is to remove the distributors on this engine, I would consider sending it to a professional. Taking the distributor out and back a couple of time will end up more expensive that doing it once with a properly serviced part. No need for a full restoration though, just a good clean and lube job, with new points and calibration on a suitable tester.

 

It's always a possibility that one of your new coils is bad. It's an easy swich to verify that your problem is not one bad coil. If the coils are OK, then you need to start checking the distributor, especially the points, on the bank that is dead as others have suggested. Finding your problem is a process of elimination if you are doing this yourself.

 

Why not just get the pertronix module to replace the points and get their matching coils also. Did this on my car 13 years ago and have never had any issue with the ignition. As someone pointed out the points and condensers made today are crap, just get rid of them. There are no permanent changes made to swap over and you can’t tell it’s been done by looking at the engine.