Melted plug extender on my '79 308 | FerrariChat

Melted plug extender on my '79 308

Discussion in 'Technical Q&A' started by tommott77, Jan 17, 2010.

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  1. tommott77

    tommott77 Formula Junior

    Feb 1, 2009
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    In my pursuit to get my '79 308 up and running (properly) I just noticed that the spark plug extender on #2 has melted. I am not talking about a hole, I mean the entire part under where the plug meets the extender is gone.

    So obviously I assume that there is some arching going on in there. My question at this point is how to best proceed with the problem? To give you a little back ground, though the car has come a long way over the couple months, it still stumbles (coughing, and spitting to along with some backfiring) when you get on the throttle over about 3500 rpms. My mechanic friend and myself had been under the assumption that it is a carb related issue and that the carbs may need to be rebuilt. The last time I took the car out though it seemed to have the same stumble but when you get around 5000-5500 the missing got so bad it would hit an artificial rev limiter. In all the tuning that we have done the plugs have come in and out countless times (all plugs currently reading a little ok to a little lean while #1 and #2 appear to be way on the cold side of the spectrum). I tried the 'dark test' for about a minute or so on a cold motor in the garage the other night but did not see any visible arching.

    So before I go in and start rebuilding some Webers I want to make sure that the ignition system is working properly. Everything is still stock in there, dual distributors, dual coils, two sets of points in each distributor. I do have a dual dizzy Pertronix still sitting in the box awaiting install. Should I just start by getting new extenders and work my way up there? From searching around it looks like there might be some wire options out there that don't need any extenders, would this be a better option? Any guidance would be appreciated.
     
  2. Peter

    Peter F1 Veteran
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    The signs are pointing to that (and maybe the others) extender as a cause of your problem.

    I hate these extenders, in at least the way they attach to the plugs. You'll probably find that the little retaining spring in the end of the extender is worn out or not there at all. Your only choice at that point would be to replace it. And the rest of them as well because if this one went, the others will follow shortly afterwards. Don't pull them out and/or push them on either, I like to screw/unscrew them as like I mentioned, that little spring is weak/soft so it will wear out.

    You should also confirm that the timing is set correctly (consult your owner's manual for that info. It probably is for your car: R1 points at 7*BTDC, R2 points at 3*ATDC), that both distributors are advancing fully (34*BTDC @ 5000 RPM) and that they're in sync with each other, before attempting carb service. Get the ignition issues sorted out first.
     
  3. dave80gtsi

    dave80gtsi Formula 3
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    D'oh! Of course!

    Now that you say this, it makes perfect sense that these extenders should be screwed on and off the threaded ends of the plugs!

    But for -years- I've simply been pushing them on / pulling them off the plugs, not really thinking this small detail through very deeply.

    I've learned something new today - many thanks for pointing out the (to you) obvious, which in my case was not obvious at all!

    Thanks and Cheers - DM
     
  4. BigTex

    BigTex Seven Time F1 World Champ
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    It's a spring steel clip grabbing the threaded plug end..

    It's meant to be pulled straight off, IMO.

    If it's missing it means the extender is broken and needs replacement, it's an $8 part.....

    Now carb problems CAN increase the temps of the heads, so I'm not saying that's not possible, but normally extenders last a long time..

    Cracking and side arcing is the most common mode of failure.
     
  5. tommott77

    tommott77 Formula Junior

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    New extenders were ordered today from T Rutlands. Due to the condition of the clips of all the other extenders I felt it would be wise to go ahead and replace all eight.
     
  6. BigTex

    BigTex Seven Time F1 World Champ
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    Why not......it may well be a source of your misfire, especially the one that had NO clip????
     
  7. 2NA

    2NA F1 World Champ
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    That's it.

    They fail, need replacing, probably will fix it.

    It's a good idea to measure resistance of the wires also. They might need to have the ends trimmed a little and fresh connectors.
     
  8. BigTex

    BigTex Seven Time F1 World Champ
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    Thanks....I've never "threaded" one off.....I thought I was missing something here......

    Now, I forget to remove the plug ferrules ALL the time.....LOL!
     
  9. tommott77

    tommott77 Formula Junior

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    #9 tommott77, Jan 20, 2010
    Last edited by a moderator: Sep 7, 2017
    I got the new extenders in the mail today, and installed them along with the NGK BP5ES plugs (gapped at .025") that I got late last week. When I first started the car I was hopeful that the problem was solved as the car took throttle much better than before without load. I took it out for a drive though and it quickly became clear that the symptoms were still persistent and the car would not go over 5500 rpms due to all the missing. To throw salt on the wound it felt like something went wrong in the steering as it seemed that all of sudden I had much more play in the steering wheel. Arrhh! This could just be me imagining things, but I will jack the car up to look at the front in the next couple days to be sure.

    But back to the point. Though my mechanic buddy felt that it was a carb issue to me it seems more like a spark or timing issue as the car cannot be coaxed over 5500 rpms. My next task will be to test the resistance in the plug wires. Any suggestions as to the proper procedure and readings would be appreciated. After that I am not sure where to go? I have little to no experience when it comes to ole school distributors and points, needless to say with two sets of distributors with two sets of points each. Trying to go through all this and the ignition timing has me somewhat intimidated. I also have a dual dizzy Pertronix setup sitting in the box that has not been installed as of yet due to the above reasons.

    I do feel much more confident with rebuilding the carbs myself but I am not sure if this would be wise to do prior to checking the ignition system in it's entirety. I will say though that it seem that most of the spitting and coughing is emanating from the passenger side aft Weber, and from checking the two plugs under that particular carb it seems that those two plugs are not firing nearing as efficiently as the rest of the cylinders (cold looking, smell like gas).

    Btw. In poking around the ignition system I found the wire pictured below just hanging out on it's own. Anybody have an idea as to where it supposed to go to? It is a lone wire with a plastic plug end that sits right in-between and under the two coils. Perhaps that could have something to do with my missing woes?
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  10. Peter

    Peter F1 Veteran
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    Hard to say... Do you know if your car has the dual points still (R1 & R2), or has been made to run on only one set of points (R1)? If it still has dual points, there should be a little microswitch acting off the throttle shaft of the rear, passenger-side carb. I find it difficult to tell what the colour is of that wire. Is it black or brown?

    Did you check that the timing is set-up correctly, that the distributors are advancing fully and are in sync with each other? I've experienced in the past a similar situation (no power and awful running characteristics) above 5000 and had been quite a gradual progression to get to that state. This was due to the advance mechanism's internal bits wearing out, causing it to max-out sooner and not any further (and therefore not at the appropriate degrees at the appropriate RPM).

    If it's worn out, you'll have to remove the distributors and have them rebuilt and tested/sync'd on a distributor testing machine.
     
  11. Peter

    Peter F1 Veteran
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    - A little bit off-topic here -

    Your car's body assembly number is 1105 A. This number is stamped on top of the coils mounting bracket and is in plain view in your photo ;)

    This number should match many other components of your car, including the doors, interior trim pieces, (and at least on 308 GT4's) headlight-pod brackets, etc...
     
  12. BigTex

    BigTex Seven Time F1 World Champ
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    Peter is onto it...

    You need to check the mechanical advance of the distributors.

    One of those "every 3000 miles" things on these cars is to lube the unit.

    Everybody raise your hands, on that one????

    Also, good you narrowed the gap but for the early cars .025 is the MAX of the gap range, they are happier at say, .o22.
     
  13. tommott77

    tommott77 Formula Junior

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    #13 tommott77, Jan 21, 2010
    Last edited by a moderator: Sep 7, 2017
    The car still has both sets of points in the two distributors. I had checked the function of the microswitch thinking that maybe if the R2 points were still functioning over 3500 rpms that that could possibly be the culprit. I checked to see if it opened and closed properly with the carbs as it did, and to check if the all the electrical connections looked tight and secure.

    ---oh and thanks for adding the bit about the chasis assembly number. I was not aware of that.

    I have not checked the timing as of yet as the two distributor setup has me a outside of my comfort zone. Not sure if there are different sets of timing marks I should be looking for with each dizzy, not sure how to sync together, ect.

    The wire in question is black. Here are several more pictures showing the wire in question along with plastic lead that sits under and between the two coils.

    A little bit off topic, but I was also wondering if there should be a ballast resistors going into each coil? I am trying to muster up the courage to follow through with the Pertronix install and I am trying to get the wiring straight in my head. This would take fualty points, and maybe even some mis-wiring out of the equation.
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  14. BigTex

    BigTex Seven Time F1 World Champ
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    The coils are modified, look on the bottom! There's a diagram on them too.

    The R1 R2 points transition is right above idle, not in the midrange. Most common mod is to disconnect it and run hi rpm dwell angle all the time.

    That's why I'm thinking to LUBE the advance mechanism, it's hanging up, maybe from wear of the bushings/weights, maybe it just needs some love.

    There IS no sync between the two banks! LOL!
    They are just tied together at the crankshaft, other than that, it's two 4 cylinders.

    The two distributors just spin happily away based upon mechanical advence against RPM, like those open spinning governors you see on antique generator sets. They can only be checked and calibrated off the car, there is no "adjustment' except in the bench tuning.

    When they are right it's wonderful, but obviously either bank lagging or cutting out entirely just lops your power curve like a New Mexico Mesa.

    HTH.
     
  15. BigTex

    BigTex Seven Time F1 World Champ
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    Trust me, fixing the stock set up (simplified to one set of points) is HALF the work of the Pertronix or other wholesale ignition mods...IMO.

    These distributors are NOT meant to be horizontal, look at all the 12 cylinder installations!!!

    But no matter, it's just reorienting the plane the weights swing thru......to vertical!

    Aside, the oil filled COILS don't like being laid over either, it exposes some of the internal winding to an air pocket. MSD makes some high vibration solid potted ones that slip right in!

    Food for thought......
     
  16. BigTex

    BigTex Seven Time F1 World Champ
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    I see one of the square ballast resistors in one of your shots....it rides the mounting band clamp strap.

    Make sure the loose wire isn't part of that wiring.....

    You only have one weather boot on the coils?
     
  17. tommott77

    tommott77 Formula Junior

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    #17 tommott77, Jan 21, 2010
    Last edited: Jan 21, 2010
    Well I shall check the advance mechanism(s). I have not opened up these dizzies past the point of taking the cap off, the rotor and attempting (sucker is on there good) to remove the plate that sits under the rotor with everything still on the car. Am I correct in assuming it is best to remove the distributors to get all the way down there? What would you recommend to use to lubricate the mechanism? It just seems though if I go to this stage of the game the Pertronix should go in.

    Bummer to hear about the 'aftermarket' wiring go on with the coils. Is the diagram you speak of in the service manual or in F-chat somewhere? Might be tempting to go the aftermarket coil route to help clean up the wiring a bit.

    Thanks so much for the help.
     
  18. BigTex

    BigTex Seven Time F1 World Champ
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    I'll see if I can find the little sketch, it's no large deal it just shows how that wiring connects.....I think it is in the Owner's Manual.
    It's not aftermarket wiring it was how Ferrari utilized the coil as it came from Magnetti Marelli.

    You're very welcome, I'm no mechanic but I've listened closely to a few good ones...
     
  19. BigTex

    BigTex Seven Time F1 World Champ
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    I hesitate to tell you to pull the distributors, if you could lube them in place.

    Once out you may as well send them off for repair and calibration!

    Sounds like you have the Pertronix in hand?
     
  20. tommott77

    tommott77 Formula Junior

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    #20 tommott77, Jan 22, 2010
    Last edited: Jan 22, 2010
    Petronix is in hand. I will attempt to do everything on the car. I think I might need a puller to get the spider web looking plate off that sits under the rotor though. Points will be removed. I will lube (not sure what to use) and check the operation of the advance mechanism by jacking the car up, putting it in 5th gear, and rotating the tire. I will then put in the Pertronix and hope for the best. Hopefully the 'non-aftermarket aftermarket' wiring under the coils did not convolute the wiring too much. In looking in the manual there is a pretty good wiring diagram for the coils and ignition system, but it does not appear to have my myster wire and lead.
     
  21. BigTex

    BigTex Seven Time F1 World Champ
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    Sean F. (here in Houston also) has a 1977 like ours and he did the Pertronics system, IIRC..

    Maybe shoot the breeze with him, if any troubles.
     
  22. Peter

    Peter F1 Veteran
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    #22 Peter, Jan 22, 2010
    Last edited by a moderator: Sep 7, 2017
    You mention this and it brings it to my attention that I did not clarify what I meant by "sync"-ing the dizzy's... What I meant is that the ADVANCE CURVE should be the same between BOTH distributors. I bench tested two BRAND NEW distributors I purchased a few years ago and this was the result:
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  23. tommott77

    tommott77 Formula Junior

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    You know I just thought of something after looking at that graph that I want to run by you guys before I commence taking the ignition system apart. Does load have any bearing on how the ignition system operates?

    The reason I ask is because the car will rev freely past 5000-5500 rpms in neutral. Though it does spit, cough, and backfire every once in while in neutral, the main issue is not until the car is in gear and under load. Just kind of going over things in my head but spark is spark and if the advance mechanism is indeed 'stuck' then it should have the same issues with or without load. I could be wrong though.

    If load does not have any bearing over the ignition system or the advance mechanism then it seems like it could be more of a fuel starvation issue. Though the idle and main jets have been changed somewhere down the line to 55/135s, the car still has the 220 air corrector jets, which upon my research are still the 'emissions' air corrector jets. All the emissions equipment has been removed, the car has a mangnaflow exhaust and I am running individual filter screens over the stock air horns in lieu of the stock air box at the moment.
     
  24. st@ven

    st@ven F1 Rookie

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    #24 st@ven, Jan 23, 2010
    Last edited: Jan 23, 2010
    start the engine in complete darkness and look (carefully, as sparks are small but hit hard) for sparks on places they shouldn't be.

    For me is this always the first thing to do when suspection ignition problems. In many cases it showed the failure instantly.

    furthermore you have the water/dust cap on your left rotor upside-down. The holes are meant to loosen water, now they act as a help for letting water in..
    probably someone switched both distributors somewhere in the past. This could have resulted in this too
     
  25. Peter

    Peter F1 Veteran
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    In my case, no, it did not matter whether I was driving down the road, or just sitting there running while parked, the worn-out advance caused poor running above 5000 RPM.

    It should NOT spit, cough, bark, whatever while idling. Are these odd noises coming from the exhaust or the carb intake throats? If the carb intake throats are making those spitting noises, it's an indicator that that throat is running too lean (you'd have to determine if it's too small an idle jet, or the idle mixture screw is turned in too far).
     

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