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330 GTC ammeter flickering

Discussion in 'Vintage (thru 365 GTC4)' started by JimEakin, Feb 6, 2021.

  1. JimEakin

    JimEakin Formula Junior
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    Jun 13, 2015
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    At idle my ammeter shows discharge. When I rev up the engine, the needle suddenly jumps up and then flickers. It’s only started doing this. Before, the charging would track revs.

    Why is my ammeter flickering?. According to the schematic, my car only has the alternator and solid state regulator (no relay anywhere). Will an alternator rebuild fix this?

    I’ve read through the threads about alternators and one recommendation was to rebuild mine to get higher output. I really don’t want to rewire from 3 wire to 1 wire.

    I assume I have a Lucas alternator.

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  3. Dogdish

    Dogdish Formula Junior

    Dec 27, 2005
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    I had the same issue on my Daytona. Ammeter bounced and lights flickered with engine rpm. I rebuilt the original regulator and then installed a solid state regulator, still flickered. I took the alternator to 2 different reputable auto electric shops. Both said there wasn't anything wrong with the alternator. I installed a Testarossa alternator, works great. Hope this helps.....but look at armature wiring and diodes on the alternator itself.
     
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  4. TTR

    TTR F1 Rookie
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    Could also be caused by the most common culprit* in all older/vintage car electrical problems, poor ground at any one (or multiple) point(s) of the circuit.

    *Also usually the most often initially overlooked.

    Jim, based on your photos, looks like your wiring connections could also be problematic.
     
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  5. Jumprun

    Jumprun Karting

    Feb 7, 2012
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    Hi Jim, thanks for helping me with the wheel work, If you need the balancing adapter again, you are welcome.

    Ok, about your alternator, it does look like the Lucas 11AC. Mine could barely keep up so I had it rebuilt but it was only marginally better so I bought a modern high output 1 wire type but I kept the original harness for the look on junction block. Speaking of the junction block, your connections could use a clean up, and I agree with Timo, your bouncing issue could be a bad ground.
    I usually like to restore the original engineering, but I got fed up with that Lucas alternator and replaced it with modern, I am really happy with the performance.

    I’ll be happy to show you how mine is wired up when we meet up.
    Although my new alternator looks modern, I can also show you a another modern one that is hard to tell from the original Lucas.
     
  6. 330BRC

    330BRC Karting

    May 4, 2007
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    The alternator on my GTC had similar symptoms. I rebuilt the alternator and replaced the regulator. No change. I wiggled the correct fuse and it fixed it. It was a very good lesson in starting with the simple stuff. I now put a small amount of dielectric grease on the fuse ends.
     
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  8. Wheels1

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    Also the ground on the back of the ammeter is worth removing and cleaning, when cleaned WD 40 works quite well for contacts if you have not got the correct stuff.
     
  9. jimmyr

    jimmyr Karting

    Oct 10, 2004
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    The ammeter function does not require any grounds to function, the ground wire could be for the dash light in the gauge. Poor grounds are a common fault of these charging systems: the regulator ground, the chassis to frame ground that should be on the bellhousing, the braid strap from the battery frame to the block are some of the ground problems on these cars. The next areas are the regulator fuse, alternator junction block, and possibly the ignition switch connections. If increasing the engine RPM higher than usual to see a charge it could be the alternator itself if all of the other items mentioned were OK or serviced. Lucas alternators are problem for shops testing them as they have some uncommon design faults that are difficult to analyze and test good when they are not fully functional. Poor brushes, slip rings, intermittent diodes and windings are just a few of their problems.
     
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  10. Drew Altemara

    Drew Altemara Formula 3

    Feb 11, 2002
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    I had this issue on a Daytona.

    Went through all the connections - was better and did not flicker as much under load. But still bothersome.

    When I replaced the two electric fuel pumps the flicker just about vanished.

    Go figure.

    Drew


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  11. JimEakin

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    Didn't find anything online, except for a replacement from Fosseway in the UK. So I just looked up "alternator nearby" on my iPhone and went searching (driving around) in the Riverside area. At my second stop, I was referred to AutoTech Engineering in Riverside. I had taken by alternator with me. Sam at AutoTech was able to come up with a new alternator with a close-enough bracket. It is a 100 Amp unit with an internal voltage regulator. It's a custom component, so no part number.

    Note that the new alternator also has a smaller pulley, so the alternator becomes more effective at lower revs. My car is nowhere near concours. I plan on driving the car and I don't want any reliability issues that might come up again should I just rebuild the Lucas alternator.

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    AutoTech Engineering
    1110 Palmyrita Ave
    Riverside CA 92507
    951 289 9202
    https://autotechengineeringusa.com

    With the internal regulator included in the alternator, I don't need the voltage regulator on the car. I looked at the schematic and I do need to remove a fuse just to make sure the regulator is completely disabled.

    (Aside: Once I had the "original" Lucas alternator out of the car, I noticed that the main mounting bracket had broken off and then had been welded back on. Makes me wonder what went on with the car over the years.)
     
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  13. TTR

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    Nothing much to figure, as it’s all pretty simple when you think about it.
    Anything drawing current (=amperage) or causing (unexpected) resistance, like poor connections/contacts, can and will affect operations of ammeter.
     
  14. TTR

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    I've lived and have had my (vintage car) restoration business in Riverside for 30+ years, but never heard of this outfit. Must be somewhat new.
    Did at least they test the old one and deemed it faulty ?
    Please, let us know if replacement alone will fix the issue.
     
  15. JimEakin

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    Hi Timo,

    Sam wound up not checking the old alternator. But I was pretty much done with ot when I saw the support had been welded back on. I don’t want to be driving back from Monterey on Sunday night and have an alternator issue. I’ll keep the Lucas for the next owner.

    I plan to have the car on the road again this weekend. I would appreciate setting up an appointment for an alignment with you and then see what you think of the car.
     
  16. TTR

    TTR F1 Rookie
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    Jim, I’ll pm you with my direct contact information.

    I would also recommend making any connections to new alternator easily reversible by creating short pigtail connector harness instead of changing or modifying any OEM wiring ends.
     
  17. TTR

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    Additionally, while the difference in pulley diameters doesn’t seem very big and may not be an issue, I’d also check the new alternator is designed/engineered for and capable of handling higher RPMs associated with your car.
     
  18. jimmyr

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    Oct 10, 2004
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    Keep an eye on the wires that carry the heaver alternator current as they were designed for a much lower amperage. Likewise the ammeter could also be damaged.
     
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  19. JimEakin

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    Thanks for everyone's replies, much appreciated!

    I went ahead with the install of the new alternator. The flickering on the ammeter went away. But when I put my DVM on the battery, the display went ape-****! Admission: the flickering started with the old alternator after I put in a new belt. Thinking about this, I went to the hardware store and got a internal toothed lock washer and installed it against the alternator support on the engine. This way, the tangs on the lock washer would dig into the support on the engine to make sure there was an adequate ground. I wasn't thinking about this before with the old alternator.

    After installing the lock washer, the voltage on the DVM is rock steady now, up to about 14.6V max when engine is revved. Ammeter is steady.

    I do need to check back with the manufacturer regarding the revs. But the new alternator does start charging much sooner than the old.

    Amp ratings: the Lucas unit had a label stating it was rated for 60 amps. I just went to a 100 amp unit, relying on the smaller pulley to give charging sooner. The other thing I wanted was to go to a shop and be sure that the bracket would work (well, I wound up getting a Mr. Gasket hot rod bracket - yes, blasphemy!). It was also important that the center of the pulley was in the correct alignment with the groove in the damper. This all worked out great.

    More amp ratings, and car wiring: it doesn't matter if you have a 60, 100, or 300 amp alternator installed. The electrical system will only use the amount of current needed for all accessories. Knowing this, I just wanted a little extra boost to be sure there was enough for everything. A recent post here mentioned that there were issues with the Lucas unit when high beams, radio, A/C, etc., were on all at once. Increased amps from the alternator will allow this. The wiring in the car should be set for all of this. (The main reason for a high amp alternator and beefed up wiring is when you add a winch to your Jeep, a 1,000 Watt boom box, or all the trick lighting to your truck.)

    I did remove the fuse for the "Regulator," and the wiring for the field is disconnected. Should the day come to sell, it's pretty easy to put everything back to original. I used the same wiring from the alternator output to the post on the inside of the car.
     
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  20. DWR46

    DWR46 Formula 3
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    Jim: Just a words to the wise. When Jimmyr says something about Ferrari electrics, you can take it to the bank. He has forgot more about Ferrari electricals than the rest of us will ever know. He is my absolute go-to source when it comes to electricity.
     
  21. turbo-joe

    turbo-joe F1 Veteran

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    what is a DVM?
     
  22. JimEakin

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    I looked this up for reference. It also speaks to Jimmyr’s comment.
    https://www.lifewire.com/high-amp-alternator-damage-534775
     
  23. JimEakin

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    Digital voltmeter. There are DVMs built into USB chargers that plug into the cigar lighter.
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