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308 Carb - Hard start after several days sitting

Discussion in '308/328' started by Nuvolari, Mar 25, 2021.

  1. Portofino

    Portofino Karting

    Sep 17, 2011
    228
    Yorkshire UK / Switzerland/ Cote d Azur
    Full Name:
    Portofino
    As a side shoot I bought a 208 GT 4 at auction , it’s got 34 Webber’s not 40 s like the 308 .
    Then only thing in bold font was a A4 paper on the passenger seat with “ full choke do not press the accelerator after 20 seconds ignition “
    In a smaller font “ If you depress the peddle it will not start “

    Like the OP and after reading up about carbed 308s and listening to other owners all 3.0 L variants they waxed lyrical about zero choke ( even bragging its been taken out ) two pushes of the peddle and catch it method .

    I will tell you now that does not work and leads to flooding with the 34 s .

    Yes I have checked and do regular checks the choke turns off conscious you guys report they stick on with your 40 s .

    Cold = full coke no touching the peddle , and pick it up once it’s fired up and running .30 secs then take off the choke and let it breath out with a few low blips .

    Warm 1/2 choke , and catch it as it fires .It will not fire with no choke , just cranks over and eventually floods .

    Hot I mean oil temp up no choke needed .

    So when I drop it off at Ferrari specialist or normal mechanics I pull this A4 sheet out and leave it on the seat .


    Without cold choke it’s impossible to start .
     
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  3. Portofino

    Portofino Karting

    Sep 17, 2011
    228
    Yorkshire UK / Switzerland/ Cote d Azur
    Full Name:
    Portofino
    Just to add I came into this carbed Ferrari from a 360 and previous to that a Testarossa. But all my garden tools required choke to start and some are sitting for months unused and fire up with a bit of choke .

    So the 208 fitted my previous carb ICE experience.
    It’s only after I bought it others told me about the no choke method with the 308;

    There s no way a garden tool will fire up and run without choke if cold .
     
  4. samsaprunoff

    samsaprunoff F1 Rookie
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    Jun 8, 2004
    3,303
    Edmonton, AB Canada
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    Sam Saprunoff
    Goods day Rob,

    Although my comments may be unrelated to your cold start issue, I think it is important to understand that there are two electrical parameters that are needed in order to determine if an ignition coil is OK. Your comment implies that the voltage to the coil looks fine and does not drop appreciably during cranking. This is important, but is not taking into account the current being fed into the transformer. Voltage is one aspect, but current denotes the energy being fed into the coil which ultimately affects the coils performance. Effectively the coil's primary (low) voltage could be OK, but the rate of current being fed into the coil could cause coil output issues (e.g can your battery/alternator supply adequate current to the coil when needed?). Another factor is the efficiency of the ignition coil, as ultimately there is an energy transfer between the primary and secondaries of the coil. A reduction or degradation of the ignition coil efficiency (or an increase in losses) would also affect the resulting high voltage spark and energy being fed to the spark plug. Over time an ignition coil can degrade simply because of the high voltages present over time. There is far more electrical and transformer theory in all of this, but my point is that the input voltage level on the primary side of an ignition coil is simply not enough info to make an assessment of an ignition coil's state. If anything it will give you an indicator, but no more.

    As smg2 stated, to truly test and evaluate an ignition coil, specialty equipment is needed which most people and even shops do not have. Given that ignition coils are relatively cheap, it is sometimes easier to buy and try a fresh coil just to confirm or refute that the ignition coil is a factor.

    I hope the above makes sense.

    Cheers,

    Sam
     
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  5. TonyL

    TonyL F1 Rookie

    Sep 27, 2007
    3,029
    UK
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    Tony
    Rob
    I dont see what would change in a few days that would make the car is difficult to start except a few possible causes. Nothing can change that much in a short time! We all know cars have little quirks in starting but most complicated starting techniques are fantasy in all reality.

    - Low Battery (enough to crank but not for the ignition)
    or bad plug / s after the last run. ie Carbon fouled.

    Like you I am not 100% on the various ancient after market ignition systems used 20 + years ago so would be nice if you could explain the Pertronix system in a little more detail, ie is it Ballast res.

    You say you did a full top end service, did that include valve stem seals - does it smoke on start up?

    Did it have this problem before?

    Personally I dont like the EVIx plugs, the 308 runs perfectly OK on BP7ES plugs.

    Are the float shut off valves good?

    when it wont start what do you do to get it fired up?

    are all the plugs wet fouled?

    Tony
     
  6. mike32

    mike32 F1 Rookie

    May 13, 2016
    3,351
    Uk
    See if you can find some info on the carb jets, have you considered that it might have pilot jets that might need cleaning out. If they are not doing their job you may be having to give it more throttle to get it to catch and possable flooding it. I have only worked on a mondial injection system so this more related to a motorbike i had problems with. The brass jets had furred up with a green slime and gave starting problems- try some carb cleaner in the fuel tank in case that shifts it
     
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  8. Nuvolari

    Nuvolari F1 Veteran
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    Sep 3, 2002
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    Rob C.
    Guys thank you all for the continued help. Some answers to asked questions:

    - Jets have all been checked and are clean

    - Battery is strong and the car cranks really well

    - Engine top end was re-built a three years ago with new valves and valve seals. There is no leaking nor is there oil/cooling consumption. No smoke on startup

    - Plugs look good however I am going to try a hotter range plug as they are a little on the dirty side. This car gets driven mainly in transient throttle without the chance for a lot of high speed running so a hotter plug should keep cleaner. After years of using the Iridium plugs I will try my hotter plug experiment with standard plugs as they are cheaper and 'might' be better suited to a conventional (non electronic) ignition system. Stock is a 6 range plug and there are plenty of threads that claim better running with a 5 range plug so I'll try that. It's an inexpensive experiment with no real risk.

    - When I say I have a Pertronix ignition I am only referring to the trigger in the distributor that replaces the points. Everything else is conventional and the advance mechanism has been tested for proper operation. Spark plug wires and plugs are new and the cap and rotor are in excellent condition.


    The car sat for 3 days so I tried a few things:

    - Looked down the barrels of the carbs with the fuel pumps running and confirmed that there are no leaks and that the accelerator pumps are spraying well and evenly

    - After 3 days it started pretty easily so I'll have to wait longer to do more tests.
     
  9. Fitz

    Fitz Karting

    Jan 27, 2004
    76
    Amelia Island
    Full Name:
    Frank
    The following is the setup I use on my carb GTB:
    Birdman fuse blocks
    Pertronix Ignitor
    Pertronix Coils
    Accel Super Stock wires
    NGK5ES non resistor plugs
    Remove directional fuel valve #111790
    Fcet fuel pump
    High torque geared starter
    Non ethanol fuel
    Starting is done with two pumps on the accelerator hold down 1/4 throttle and crank. Hope this helps, it works for my 308.
     
  10. smg2

    smg2 F1 World Champ
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    Apr 1, 2004
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    Dumpster Fire #31
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    SMG
    Silver or copper plugs... Everything else toss in the bin. Just my experience from lots of engine builds and more time then I care on the dyno.
     
  11. Nuvolari

    Nuvolari F1 Veteran
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    Sep 3, 2002
    5,649
    Toronto / SoCal
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    Rob C.
    Progress update

    I looked down the throat of all the carbs while the fuel pumps ran and found no problems. I also checked the accelerator pumps and visually they all seem to be spraying the same amount. For this reason I think the carburetion and fuel system is good.

    Turning to the electrics I did the basic checks of good contacts and wire continuity. Again all good. Checking the spark plugs I found them to be a little dirtier than I would like but at least they all looked even relative to one another. I have been using plugs one temp range colder than stock (NGK BPR7EIX iridium plugs) for some time and decided to go one temp range hotter than stock using NGK BPR5ES conventional plugs (two temp ranges hotter than what I had) as the car is generally driven in regular road conditions with little extended hard driving as you would do on a track.

    With the new plugs so far so good. The engine is a little crisper off idle and pulling out of slow corners. I have not done a check of the plugs yet but I can only assume they will be closer to ideal in colour. I'll keep my eyes on it and report back. Thank you all for your suggestions and feedback.
     
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  13. TonyL

    TonyL F1 Rookie

    Sep 27, 2007
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    Tony
    Sounds like you are making some progress Rob, I changed to the BP6ES . Do you need the resistior plugs ?
     
  14. Nuvolari

    Nuvolari F1 Veteran
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    Sep 3, 2002
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    Rob C.
    As it happens the non-resistor plugs in the #5 heat range were very difficult to find so I bought the ones with the resistor which were readily available everwhere. I'm not exactly sure what the difference is for the conventional ignition system I have. The quick research I did was that the two are interchangeable.
     
  15. TonyL

    TonyL F1 Rookie

    Sep 27, 2007
    3,029
    UK
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    Tony
    My rather limited knowledge is that the 308 has 5k resistors in the plugs extenders so the plugs can be non resistor type.
     
  16. maxflynn

    maxflynn Karting

    Feb 9, 2015
    99
    GTA
    Full Name:
    David
    Were the plugs the culprit after all?
     
  17. Nuvolari

    Nuvolari F1 Veteran
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    Sep 3, 2002
    5,649
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    Rob C.
    So far everything is pointing to the plugs. With the new hotter temperature plugs the engine starts better and is running cleaner and crisper especially at very small throttle openings. I have non resistor plugs on order and will try them when they arrive next week. So far so good.
     

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