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Thread: Stalling and popping

  1. #1

    Stalling and popping

    Hi my car is stalling at times when i press in the clutch. I ran out the engine a few times in hopes of burning debris off the points. It definitely helped but car still will occassionally stall when cold.

    Also, exhaust is popping a lot - is that running lean or rich? May also contribute to stalling. Can i adjust the mfi mixture myself or bad idea?

  2. #2
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    Quote Originally Posted by wsf80 View Post
    Hi my car is stalling at times when i press in the clutch. I ran out the engine a few times in hopes of burning debris off the points. It definitely helped but car still will occassionally stall when cold.

    Also, exhaust is popping a lot - is that running lean or rich? May also contribute to stalling. Can i adjust the mfi mixture myself or bad idea?
    Old thread, but my car is doing exactly the same as this. Fresh build 3.2 SS engine running 46 mm PMO's. I have adjusted thr idle to 1200 rpm, but its not very stable and seems to vary between 800 and 1500 rpm. I have checked the idle squirters are correct, set the timing, checked the carb balance, recharged the batteries and changed the plugs (older plugs, but the previous ones were new) but its made no difference.
    I have ordered 2 new batteries, new distributor cap and rotor and another set of new plugs. I have been speaking to the engine builder, Richard Parr and Barry who recurved my distributor. I've tried nearly everything they've suggested so far, but at waiting for the new parts to arrive for more tests.

    I'm running out of ideas and getting frustrated. I read something on Pelican regarding someone who had a problem with erratic running, which turned out to be the coil. I have a 2 year old MSD ignition with a MSD high vibration coil. Its possible this is the problem, but could be many other things.

    Unlike the OP, my car is not popping and misfiring. Its running a bit rich, but i dont think that would cause this problem.

    The engine builder is about 5 hours away, so i'd rather try a few things myself before taking it back.

    Any suggestions?

  3. #3
    What have Richard and Barry suggested? Seems like the engine builder should be doing this,,,not you.
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  4. #4
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    That's true. I'm translating between German and American, so i am discussing the problem with them both and testing various things. The plugs were fouled, which meant the engine wouldn't start ar all, and the health of the batteries is questionable, so the plugs have been changed and i have ordered 2 new hi power Varta batteries. I have checked the carb squirters and need to check the idle valves (which is my only remaining test) however, the consensus is that my problem is probably electrical/ignition related rather with the carbs/fuel.

    Regards
    Paul

  5. #5
    Since you seem to have to do this yourself I'd recommend you get your self a air/fuel ratio meter,,,,the kind of tool your engine builder should have and use! We need to agree on terminology here,,,,what are carb squirters and idle valves??? Sounds like you have too high of a float level and too rich of jetting, maybe too high of fuel pump pressure. Going to need start at the beginning and work thru this logically, doubt if it is battery, cap or rotor related though.
    Early S Registry member #90
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  6. #6
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    The engine appeared to be running fine when I picked it up. I went for a 45 minute test drive through the German countryside with him next to me. All was well. No stalling problems and the car ran very well. I then drove it back to Switzerland, which is around 5 hours. It was getting cold and starting to snow. Near the end of the journey the car starting stalling when I braked and put my foot on the clutch. I originally assumed the problem was because it was so cold, so put the hand accelerator up a bit, so that it was running around 3k rpm. This sorted the problem.

    Regarding the squirters.....
    If you peer down the carb air inlets there is a small jet protruding into the carb body. When you pump the gas you get a small squirt of fuel. This is was Richard refers to as the squirters. They are supposed to pump between 5 and 6 ml of fuel on each pump. Mine are spot on.

    Idle valves... I meant Idle jets. I some different jets to try, and will try putting some slightly larger ones in next weekend.

    The batteries are not in perfect health, so I'm replacing them regardless, but I agree. I don't think that's the problem. Same with the rotor and cap, but I like to have spare service parts in stock, so I will give it a go regardless.

    I'm travelling this week, so won't be able to try anything else before the weekend.

    Regards
    Paul

  7. #7
    Knowing that it ran fine when picked up changes the diagnosis. Basic settings such as jet sizes don't change while driving, conditions such as altitude, dirt in jets, weather conditions , (icing?) different fuel
    do change.
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  8. #8
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    I drove across the country when I bought my car, from California to NYC. I visited places I knew about but had never been, one of those was Leadville Colorado, 10,000 feet up and on the side of a mountain. Up there my car ran just as you are describing. Einsiedeln, only seems to be 3000 feet up, so maybe that's not it or as Ed says, it is. He is the Porsche whisperer.
    1970 911S
    1963 Abarth Monomille
    1974 2002 Turbo

  9. #9
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    Hi,
    The problem doesn't go away when I drive to Zurich, so I don't think the altotude is a problem. I also have the problem when it's about 20 C, so probably not icing either, but I'll try changing the jets at the weekend. It could be some dirt in the Jets.

    Regards
    Paul

  10. #10
    Dirt in the needle valve could cause a high float level and rich mixture in those affected cylinders.
    Early S Registry member #90
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