I have a '79 308 with dual distrib. and running only the R1 points. The other day after 1000 miles of problem free driving (not all on the same day ...) , I had my rear bank drop off line. After my previous in depth trouble shooting efforts, I knew immediately that it was an ignition problem. After checking the varioius wires from the coil to the distributor and determining that there was no loss of voltage or broken/damaged wires, and checking the coil, I found that the points were at fault. When I pulled the distributor and checked the points, they did not look that bad at all. They were perfectly smooth except for about a 1/2 mm pitted "burn mark". Well, I sanded that down with some 320 grit, cleaned and replace. Initially I set the gap at .35mm (recommended .35 +- .03). That was giving me a dwell of about 15 deg. I reset a few times and determined that .30mm gave me 34-35 deg dwell. Great! The problem I have is that I still had some popping at idle that was only present with the rear cylinders working. Also, I should mention that when timing the rear bank the strobe will jump from where it should be, to a different section of the flywheel. OK, so I am getting some crossover between wires somehow. I pulled various wires on the rear bank while it was running and discovered that I was getting an rpm drop when the 3 and 4 cylinders were pulled, but not when the 1 and 2 cylinders were pulled. When I pulled the #2 wire, the problem went away (the strobe "jumping") Now the wires checked good (normal resistance) and they are fairly new (about 2 months old). I also check to make sure I was getting a spark from the plug (pulled the plug and grounded to the block while running..) All was fine. It would seem that somewhere I am still getting some jumping between the two wires. I did separate the #1/#2 wires from the stock bracket that bolts to the cam/valve cover to keep the wires together. This seems to have worked somewhat (or it could just be my imagination at this point...) I did see someone else that had a similar problem a few years back on this forum, but the problem was never really resolved here. (he was a guy working on someone elses car and got roped into fixing more than he originally signed on for. It was apparent from the thread that he really didn't want to work on it, so he didn't really have any vested interest in actually fixing that problem...) So anyone else have any thoughts or ideas that might help me here? I am considering going to electronic ignition, but I don't think that will really help my "current" problem (pun intended). Is it possible for the #1/#2 cylinders to be shorting across one another at the block? What would cause that? I thought it might be a cracked extender, but those are new also. I may just try replacing/trading those out next anyhow..... Any help would be appreciated. Thanks guys!
What color extensions, what make and number spark plugs, and what wires are on the car? What did you get for ohms on the wires?
As a quickie diagnotic, spray a fine mist of water on the #2 wire while it's running in the dark. If you see arcing your "almost new" wire is no good. Ken
Hi JR, It sounds like you have been real thorough. Since the whole bank failed, and you found the point problem, I would stay on that thought. Make sure that the point is insulated properly from the housing. High voltage can arc in a lot of ways causing a short. Check the feed-thru going throug the dizzy. Make sure that the lead cannot touch that housing and has a fair creepage (distance across the surface) and clearance (point to point as the bug flies to the surface through air) distance. A pitted point should not have caused your whole bank to fail so you may have only fixed the problem through disassembly...I dunno. Oh, also check the condensor or just put a new one ($4). That can cause uneccessary sparking and maybe mifires i.e. popping. As you know, this is really a simple system but all the pieces have to be working or she will act wierd. It is actually a testament to this old design because, in some cases, the darn thing runs even if the wiring is hosed. One thing...go through the GT4 service manual and find the section that shows the firing order. Stare at it and the car at the same time and convince yourself that your dizzy is in the right position rotationally with respect to the block, that your distributor contact inside is going in the right order, that your plug wires are in the right sockets. Just because the lengths may tell you where they go, doesn't make it right. In my 308 early on, I found two wires swapped but had the lengths set up optimally for the way they were connected! Fooled me good. 29 years is a loooooong time of folks working on her. Sorry if you've done all this...maybe it will spur your troubleshooting somehow. Advice is cheap! Oh yea....don't go electronic...you can fix this. Good Luck, -Rjay
Also noticed that my intermittent exhaust popping goes away when the #1 wire is off.... Definitely something going on between the distributor and the plug causing an intermittent short.... Still think it's odd that there is no RPM loss when pulling either the #1 or #2 wires. Could this be normal and just due to the configuration and firing order? Also rechecked the firing order in the manual and on the cover: 1, 3, 4, 2
just did the night check of the engine bay for arcing. Sprayed with water mister. No arcing. No popping either. With the wire on or off. very odd. Maybe it has something to do with the UV during the day I guess I'll wait till the engine cools (morning) and try changing out that wire....
Okay, thats all good. I second what Bob wrote. Go back through everything from scratch, regardless how stupid it seems, you missed something. You can swap wires at the coils and see if the coil is bad. But it could also be the wire from the coil to the distributor, they can break or short internally, dont be fooled. Make sure you have good grounds. There should be two uninsulated flat weave ground straps on either side of the gearbox to the frame. You can swap condensors to test them. Make sure the coil terminal nuts are tight, those have caught me a few times. Make sure the wires are installed in the cap correctly. Make sure the carbon brush isnt stuck broke or missing. Dont be discouraged. Points systems will perform as well as most any electronic ignition, but they do require more maintainance and are far less tolerant of weakness anywhere in the system. Its all gotta be right, and they force you to be more thorough. You can have a pretty tired HT system and never know it with electronic, because the higher voltage can burn its way through to fire the plug. Electronic systems need just as much maintainance in the HT side, but most everyone just drives until the car wont run. By the time it gets bad enough it will usually just outright die, theres generally no middle ground symptoms of bad performance. With points its usually a long drawn out death of ever worsening performance. In fact they usually wont just die or leave you stranded, theyll just run so awful youll eventually give up and go figure it out.
Have you pulled the wires off the battery and cleaned the terminals and the connector clamps? Have you checked the positive wire to see if it is broken or cracked?
Have you checked coil voltage output? I have had a couple of instances (not on Ferraris) where there was an internal short in the coil, thereby reducing output. Sympton was the car would idle but with added gas the extra cylinder pressure would snuf the spark and it would missfire.
You might need to have a good look inside the distributor cap. The spark could be jumping between terminals there due to cracks or tracking. I hope not though, cause that generally means a new cap and rotor and that is painfull ($$$$)
Well, problem solved (for now). It wasn't the extender or the cap or the coil (i have spares to check these). But after changing out the #1 plug wire and re-looming the wires (not all 4 crammed into the single bracket that's really only big enough for 2....), the "jumping" of the timing light seems to have gone away.... Also the popping was due to the mixture being a bit rich on the #1 cylinder. Gotta love individually setting each cyl w/ the webers! In some respects, it makes it easier. Or maybe that's just my warped sense of reality. Thanks for the tips fellas! Happy motoring!
