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After seeing all the carb related posts here, I have a few questions! I have a 1974 L-48. The date (I think) on the RCQJ is 0871, stamped on the driver's side below the part number (I think) 17029207. Clearly, not original to the car. First, is this a carb worth rebuilding (I recall a Lars post about asking before considering a rebuild). How much CFM (ish) is this capable of? I originally was going to go EFI, but if this is a solid carb, I may change my mind and defer the funds elsewhere. I know it's filthy, she's in my garage for the first time for the winter and I am starting to go over the car a bit more thoroughly. Lastly, is there much difference between the original carb and this one? The block matches the VIN, just curious as to why a swap may have been done. Part and date code?
From: At my Bar drinking and wrenching in Lafayette Colorado
Somebody has mix-and-matched components from two different year carbs on your carb, which is 750 cfm. Your throttle plate is from a 1974. The rest of the carb is a 1969 Service Replacement carb built in 1981. The carb shows a severe case of black exhaust sooting in the throttle bores, which indicates you have some significant tuning issues not related to the carb - most likely retarded timing and/or a defective or incorrectly hooked up vacuum advance control unit. That carb can be set up to run well in spite of the incorrect throttle plate for the 1969 carb. The person installing that carb probably took the throttle plate off your original '74 carb and swapped it over, since the 1969 carb does not have vacuum fitting provision for the power brakes in the back of the carb. I'd fix your timing problems before diving into the carb, though...
Thank you! I suspected tuning issues. Before I put her away, I stomped on the gas pedal from a dead stop. It backfired through the carb! May I send you an e-mail for your tuning guide?
From: At my Bar drinking and wrenching in Lafayette Colorado
A backfire up through the carb is a sign of a lean condition. Chances are good your carb needs an accelerator pump or you have a problem with the secondary airvalve opening rate. That's not to say you don't also have some timing tuning issues as evidenced by the reversion sooting in the carb. Drop me an e-mail request for my timing papers - never use any of my papers you find posted by other people on the Internet.
Lars V8FastCars@msn.com
Carb question
