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Hello there - I recently bought a very nice low-mileage 1979. Originally an L82, sometime before the last owner (I would be owner #3) obtained the car in the early nineties the L-82 was replaced by a ZZ3 crate motor. I was (not now) having starting issues with it so I pulled the air cleaner to figure out what kind of Edelbrock was on it to perhaps order a rebuild kit or send it out to be rebuilt. There are no identifying marks on the base of the carb where the Edelbrock site says to look, only a tab attached to one of bolts with "1904" on it. This would decode to a 500cfm manual choke unit intended to work as one of a dual-quad setup, so I don't think this is right (and 500cfm seems small for this engine). Any guesses? See anything really out of sorts so far on this engine other than it has no fan clutch?
Years ago I purchased a brand new 1903 to use on my 77.
Similar carb except the 1903 is setup for the hot air choke not electric like the 1904.
Never could get it to run like I think it should run.
The port for the vacuum advance on the 1903 & 1904 is ported vacuum not full manifold vacuum.
You can see from this photo the 1903 on left and my original 77 carb base on the right the slot is not visible when the throttle plate is closed vs visible on the 17057204.
Thank you @lars and @bmotojoe . I read through Lars's post on rebuilder a forum member's carb and your knowledge is really impressive. So what's your opinion on the carb? Is it something that could be rebuilt by someone of reasonable mechanical skills? I have rebuilt many sets of SU carbs on 240Zs but never something as complicated as this. My 1967 Camaro used a Mighty Demon 750 new out of the box, tuned by the engine builder so I never really messed with it. The car runs well, especially at higher RPM under heavy throttle, but at low RPM sometimes stumbles and it smells like it's running rich. Joe, so far I haven't had any vacuum-related issues other than the left headlight is sometimes slower than the right.
From: At my Bar drinking and wrenching in Lafayette Colorado
The Edelbrock Q-Jet re-pop carbs were actually very good. They were built under license from Rochester using the original Rochester tooling by Weber. The carb will run quite well when set up to it's original, factory specs.
However, before touching the carb I'd suggest you look at your other engine tuning parameters: I can see that your throttle bores are black on the inside. This is caused by exhaust reversion sooting, which is a sure-fire indicator of engine tuning issues not related to the carb. Your timing is likely badly retarded, and/or your vacuum advance is not correctly hooked up or functional. Fix your timing problems first, and then see if you have a carb problem.
My quote: "90% of all carb problems are timing problems."
Thank you very much; I'll start with that. We've only had the car a week and we're still discovering all of her secrets. Here's a dumb one though - how do I attach an air cleaner to this thing? There's no central threaded rod to go through a 'standard' screw-down open element air cleaner.
It's an Edelbrock 1904, which is a 795 cfm Q-Jet M4M model based on a mid-'70s truck carb.
Lars
Nothing to do w/this convo but my 75 Cutlass Salon w/a 350 Rocket came factory w/795 Q-jet. When I restored her I bought a new Edelbrock 1904 which I then put on the 455 that sits in her now. Was surprised that a 795cfm was stock on a chocked down mid 70's 350.
Thank you very much; I'll start with that. We've only had the car a week and we're still discovering all of her secrets. Here's a dumb one though - how do I attach an air cleaner to this thing? There's no central threaded rod to go through a 'standard' screw-down open element air cleaner.
Robert
I can't tell you the length you need for an open element air cleaner but I can give you this...
The original Air Cleaner stud for my 1977 Quadrajet (also worked on the 1903) has 1/4 X 20 threads both ends with a total length of 4 5/8"
The length of threads cut that go into the carburetor is 5/8"...
If you are going to thread a piece of round stock, I wouldn't cut the treads any deeper than 5/8" going into the carb...
Hope this helps...
The 1904 is an excellent piece as stated.......I have one on my 82' Z/28.......
And yes.....check your timing......also, if it has sat a long time.....it may need an accelerator pump.....this can cause your hard starting amongst other things......
Help identify this carb?
