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Thread: Wideband tuned jetting for a stock g54b with a weber 32/36 DFEV

  1. #1

    Join Date

    tigard or

    1987 Mitsubishi Mighty Max


    Wideband tuned jetting for a stock g54b with a weber 32/36 DFEV

    I tuned one for a friend this summer after we did a stock rebuild on his car. Truck is still running great in cooler weather, and he said he cant get any traction in the wet in the first 3 gears. The response is pretty amazing haha/
    Pasting this from another forum I posted on. Some proper jetting information has been seriously lacking, so hopefuly this will help a lot of you get a lot more power out of your trucks. Sure made one hell of a difference from the crap jetting that comes with the kit.

    He is also getting 21mpg at around 75mph in the la area. Not bad for a 4wd. I could have tuned the car for a leaner cruise, but we chose the best response and pull from our butt dyno and wideband numbers.

    Posting this up for referencve, always tune at your own risk. This is what worked for me on a wideband with a stock 4x4 d50, only mod was a rebuilt engine, and no cats, and a disabled choke

    These are my notes, as I could not find any starting point for a g54b and a weber on a stock engine. This should help you get a good running starting point, where you can even fine tune it more. Keep in mind this was tuned on a 80 degree day. I suspect I may have to jet up to a 150 with a larger air corrector in the winter.

    All tuning was done on a bosch electronic fuelpump regulated to 3psi

    Also beware o webers direct on ebay. They sold us a fake weber, that had a untuneable cruise afr. We had the carb completely tuned, but it would run 10:1 at cruise. I took out my trusty made in spain weber and the problem was instantly solved. They are complete shit. Easiest way to tell other than they are super shiny, is the real webers habe a white electronic choke plastic while the fakes usually have black, and no weber casted names
    Well final jetting came out to this.

    I'd have liked to play with it a bit more, but we are happy with the tune, and she is peppy, and no flat spots.

    We left it a little rich on the top end, and it can run a little on the lean side at a 3k rpm cruise which bangs 15 to 167, then sometimes around high 14s.

    Around 60 i will go anywhere from 14 -1. which im happy with

    wot at upper rpms will prob ably fall to low 12s. with the 175 air corrector on the secondary, we were experiencing a rich condition at wot 11.6 or so, We bumped it to a 200 and were on the lean side and lost power. lookint at afrs around 13.5. U nade the call to just drop a 180 n and figured it would lean it out a few points more than the 17. We pulled the wideband off so I cannot give you a afr reading, but it is safe on the rich side.

    End result is a 4x4d50 that can light em up a little in first gear just rolling on the throttle around a corner, and one that has a nice smooth poweband with no da spots, which I think will also give quite good fuel economy. This tuned on a 80 degree day, so I am curious to see what will the weather gets colder.

    I also played a bit more with the idle jets.My carb wasn't liking more than about 1 1/4 turn out no matter how rich or lean I made the idle jets I think the weber jetting guide kinda sucks, and tuned with my wideband instead.

    The engine is also super responsive and takes a smooth foot haha.

    This carb was tuned with the choke unhooked

    I might possibly put a 50 idle jet back in the secondary, but frankly it wasnt making much difference in the warm weather.

    SO end results

    Main jets
    primary 145
    Secondary 145

    air correctors
    primary 165
    secondary 180

    Idle jets
    Primary 55
    Secondary 45

    55 double pumper jet

    We changed the single pumper out for the double, and it realllly helped out on acceleration. The extra squirt seemed to really give a seemelsss transition into the secondary, and the engine really liked it.

    idle mixture about a turn out, maybe 1 1/4 which put me around a 13.5 afr idle. the carb idled smoother richer, but frankly, thats just pissing gas in there imo.

    I believe my idle screw is in about 1 3/8 turn,

    the last 2 settings will definitely vary on car to car, but be careful when turning out your mixture screw, about a 1/8th to a 1/4 turn will turn your afr from 13.5-14:1 to about 10:1

  2. #2

    Join Date

    Richmond, CA

    1989 Mitsubishi Mighty Max

    Great post. Do you have jet suggestions as a starting point with a 32/36 on a 2.0? I'm in the Bay Area, so a little colder and more humid but also at sea level. I work as a smog tech so I have unlimited access to a dyno and 5 gas analysis. What tuning forum are you on?

    I accidentally got a fake Weber, too.

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