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  1. #1
    Join Date
    Jan 2002
    Location
    Woodham, Surrey, UK.
    Posts
    531

    MOT and emissions

    I just brought my Sumo/RV8/Edelbrock back from it's MOT. We have an agreement, my local garage and I. It will almost certainly fail on emissions, and I don't have a gas analyser, so when it does fail, the tester or I adjust the idle screws till it passes. This depends on whether the man concerned has ever seen a carburettor before.

    This year was different. One - the man knew all about Edelbrocks - excellent! Two - I've had it in bits during the winter, doing a big clean-up after getting water in the fuel. It's been running really well, and starting better than it's done almost for ever, but the screws were adjusted by me on sound and success with starting.

    The tester adjusted the screws till it passed, and tells me that he screwed them in two full turns. That's a lot - and it doesn't run as well now, and didn't want to start as I left the test centre.

    So - what do those who really understand this stuff do (without a gas analyser)? My plan, when I've drunk my coffee, is to go out to the car, find out the current unscrew position and write it down, then unscrew it a bit till it runs better. Maybe not two turns, but certainly till it sounds and runs better.

    Opinions please.....

    Bernie

  2. #2
    Join Date
    Feb 2007
    Location
    West Sussex
    Posts
    8,449
    i guess one important question is which year / set of regs are you being tested against?
    I know nothing about ede carbs, but there are usually a fair few parameters to potentially modify on these things. Perhaps a rolling road session would be useful?

    and please can I ask others not to post any ill-thought through comments that might bring this PUBLIC forum into disrepute in certain quarters of officialdom.
    Crendon Chassis No.49
    Huddart FE428 + toploader

    Not listed in the Shelby Register.

  3. #3
    Join Date
    Jan 2002
    Location
    Woodham, Surrey, UK.
    Posts
    531
    Having finished my coffee, I've been out to the car, and the screws were undone one and a half turns. I'm pretty certain that isn't ideal, from what I've read, so i fiddled a bit. It idles a whole lot better at between one and three quarters and two turns, which is what I sort of expected. I'm going to leave it to cool now and see if it feels like starting ok before giving it a run at the new setting.

    I suppose a rolling road would be useful, but only with an Edelbrock expert and a kit of springs and needles.

    B

  4. #4
    Join Date
    Jan 2002
    Location
    Woodham, Surrey, UK.
    Posts
    531
    Actually - thinking back - the tester explained that he worked on half turns - at two turns too rich, so pick one and a half. Maybe he doesn't know as much about Edelbrocks as I'd hoped. One and a half to two turns is a long way in emissions terms, as I found out when I did it myself a few years ago. There would be seem to be every possibility to be both legal and practical.

    Just need a sensible engineer with the right gear. Any Surrey recommendations?

    B

  5. #5
    Join Date
    May 2004
    Location
    Finchampstead, Berkshire, UK.
    Age
    54
    Posts
    3,566
    Surrey rolling road (farnborough), Vixpy will know if a good tuner for the carb

    Rgds

    Jim

  6. #6
    Join Date
    Feb 2007
    Location
    West Sussex
    Posts
    8,449
    if you/they know anyone with Holley expertise, that would be useful.
    I don't fancy spending a load of money on a box of tuning bits to find the best settings.
    Crendon Chassis No.49
    Huddart FE428 + toploader

    Not listed in the Shelby Register.

  7. #7
    Join Date
    Jan 2002
    Location
    Reading, Berks, UK.
    Posts
    1,559
    Are you just adjusting the idle mixture screws?
    I thought the Edels had metering rods.

    Not an expert on Edels, the one I fitted on the Mustang worked straight out the box with only an idle mixture adjustment

  8. #8
    Join Date
    Mar 2009
    Location
    liverpool
    Age
    45
    Posts
    354
    Where's sidecar Pete, when you need him?

  9. #9
    Join Date
    Jan 2006
    Location
    Chelmsford Essex
    Posts
    783
    Bernie,

    Get your self a vacuum gauge . Not expensive and you can tune your carb for max vacuum. The AFR across the rpm range can be measured on rolling road but you can do it with AFR sensors. I am not sure which carb you have but this video should help as they are all very similar.

    https://www.youtube.com/watch?v=wR_AfQjyT-A

    The MOT station should bring up your details when they come to test the level but if the car is old enough ( Donar date) you could be exempt worth checking these details. Mined is just done on smoke level as on a 1974.
    Last edited by jon1d; 07-06-19 at 10:51 AM.

  10. #10
    Join Date
    Nov 2013
    Location
    My Garage
    Posts
    939
    Also read the Edelbrock carb manual online. I have a 1404 on a RV8 and adjusted it as per the manual and shes as sweet as a nut. I also re rodded itr. So if you havent got a Carb kit buy one, its worth it
    MKIII Pilgrim Sumo. 3.5 Litre Rover V8 Towing an Eriba Puck Caravan



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