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Quick Procedure for Removing / Reinstalling Carbs

Discussion in 'Technical Q&A' started by Mike328, Jan 26, 2004.

  1. Mike328

    Mike328 F1 Rookie
    Rossa Subscribed

    Oct 19, 2002
    2,655
    Boulder, CO
    Full Name:
    Mike
    Since I just did this, I thought I would document the high level basics... Will elaborate later if needed.

    1978 308 GTS, US Spec

    NOTE: I don't discuss removal of the air box or engine lid. I assume these are already off, and it's just the carbs now.

    Tools: 13mm regular combination wrench, 13mm stubby combination wrench, 17mm combo wrench (for fuel hose connections).

    To remove the carbs I first disconnected all the fuel hoses and moved them out of the way.

    I then disconnected the throttle linkages in exactly two places (where the linkage shafts connect to the two carbs [two are driven by the other carbs] by pulling the cotter pin out and then using a flathead screwdriver to remove the end-nut out of the linkage shaft.

    I found things much easier to do if I removed the horizontal aluminum-colored bar that spans the front and rear backs, close to the driver side of the engine (distributor side) near the LF and LR (left front and left rear) carbs. I did not have to remove the oil filter; I was able to "wrench" around it OK.

    I removed the carbs in this order: Left Rear, Right Rear, Right Front, Left Front. It's tricky to get at the nuts. Some are easy, some are tough, and every carb has one that's ridiculously hard. I used a combination of the regular and stubby 13mm wrenches depending on the clearance. Also, spraying penetrant at each nut will help here.

    Note that if you do anything with the carbs, you'll want to take the tops off (five flathead bolts) and drain any fuel still present in the bowns.

    Reinstallation is similar. Make sure you get the linkage oriented and linkage arms in the right general position as there's less room to work with that with the carbs on.

    I put the carbs back on in reverse order of how I took them off: Left Front, Right Front, Right Rear, Left Rear. Don't forget your thick plastic base "spacers" between the intake manifolds and the carbs. I torqued the 13mm nuts about as tight as I could with the 13mm stubby, but not as tight as I could with the regular 13mm wrench--didn't want to overtighten.

    One note concerning getting the carbs on. The two front carbs and two rear carbs each have an adjustable "connector" that essentially syncs up throttle shafts of the carbs. You can get the carbs with the "plate" (Right Front and Left Rear) on by using a small flathead screwdriver to push the spring-loaded extender back a bit, and the plate will slide right in, allowing these carbs to seat properly.

    From here you have to recheck all the linkages and do a fresh resync, depending on what you've done to the carbs.

    Note: These carbs were Weber 40 DCNFs, 72/73/74/75. 72 [left front], 73 [right front], 74 [left rear], 75 [right rear], oriented the way you would read a book--top (front) to bottom (rear), left to right.

    Email or private message (PM) me with questions.

    Special thanks to all here for their help in doing this job.

    --Mike
     
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