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Thread: 1987 Supersprint carburetor adjustment

  1. #11
    Join Date
    Jan 2020
    Posts
    155

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    The spec sheet says Caterham BCD with high lift and short duration profile.
    1987 Caterham 1700 Supersprint
    2002 Porsche Boxster
    2004 Porsche Boxster S
    1941 Dodge Luxury Liner
    2009 Mercedes CLK 350 Cabriolet
    2017 Chevrolet Volt

  2. #12
    Join Date
    Feb 2012
    Location
    Roswell GA
    Posts
    1,009

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    One of my carbs will slobber some, I ran the car W/O the K&Ns and the clam on that side needed clean-up after a blat. That may have something to do with the amount of overlap between intake and exhaust. I've put the filters back on, but it did sound good unfiltered.
    Life happens while you're making other plans
    1995 Caterham Crossflow RHD
    1990 Miata
    2007 GMC Sierra WT
    2013 Mini (Her's)
    2014 Outback
    JOHN DEERE D130

  3. #13
    Join Date
    Jan 2020
    Posts
    155

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    Accel Automotive in Waltham, MA checked it today. Their assessment is that it runs too lean in the 2,000 to 3,000 range and needs bigger idle jets. They are on order now and I will take it back on Wednesday to have the bigger jets inserted and the car road tested. I hope that takes care of the issue.
    1987 Caterham 1700 Supersprint
    2002 Porsche Boxster
    2004 Porsche Boxster S
    1941 Dodge Luxury Liner
    2009 Mercedes CLK 350 Cabriolet
    2017 Chevrolet Volt

  4. #14
    Join Date
    Oct 2019
    Location
    SE NC
    Posts
    112

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    Look forward to the report. Changing jets is dead simple if its better but not perfect and you want to keep tweaking yourself. I'm experimenting with Keith Frank's emulsion tubes and various main fuel and air jets as well as idle jets (actually I'm on hold while I rebuild my starter), and happy to share bits once I get settled on the right mix for mine. I will say that his emulsion tubes are an improvement over the Weber F16s, at least on my setup.
    Henry
    1965 Seven S2
    1969 Elan S4

  5. #15
    Join Date
    Jan 2020
    Posts
    155

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    Good to know, thanks. I will love to hear what works for you.

    Anker
    1987 Caterham 1700 Supersprint
    2002 Porsche Boxster
    2004 Porsche Boxster S
    1941 Dodge Luxury Liner
    2009 Mercedes CLK 350 Cabriolet
    2017 Chevrolet Volt

  6. #16
    Join Date
    Jan 2020
    Posts
    155

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    I got the car back today. They diagnosed the problem as lean running at light and mid-throttle because of undersized idle jets. They were right! It's like night and day. Spitting, sputtering and hesitating is gone. Idle isn't great, but I suspect that's because they didn't adjust the idle needles with the engine hot. It idled great when cold.

    I am a very happy camper and I really like Accel Auto in Waltham, MA. They aren't cheap, but I don't care. I so all maintenance and repairs myself, and I am happy to pay a shot to deal with the difficult stuff!

    The car has had the problem since new in 1987. I am surprised all previous owners, 3, haven't had it dealt with!
    1987 Caterham 1700 Supersprint
    2002 Porsche Boxster
    2004 Porsche Boxster S
    1941 Dodge Luxury Liner
    2009 Mercedes CLK 350 Cabriolet
    2017 Chevrolet Volt

  7. #17
    Join Date
    Oct 2019
    Location
    SE NC
    Posts
    112

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    Excellent! Need a video and some sound!
    Henry
    1965 Seven S2
    1969 Elan S4

  8. #18
    Join Date
    Jan 2020
    Posts
    155

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    I'll post before and after video after the next autocross tomorrow!
    1987 Caterham 1700 Supersprint
    2002 Porsche Boxster
    2004 Porsche Boxster S
    1941 Dodge Luxury Liner
    2009 Mercedes CLK 350 Cabriolet
    2017 Chevrolet Volt

  9. #19
    Join Date
    Jan 2020
    Posts
    155

    Default

    I had something interesting happen.

    After the new idle jets were installed it runs much, much better. The smoking has also changed. At first it would smoke a lot less when hot, but today it barely smoked at all, even when cold. My guess is that a piston ring was stuck and now has become unstuck.

    Interesting!
    1987 Caterham 1700 Supersprint
    2002 Porsche Boxster
    2004 Porsche Boxster S
    1941 Dodge Luxury Liner
    2009 Mercedes CLK 350 Cabriolet
    2017 Chevrolet Volt

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