need basic advice on adjusting 68 Camaro Edelbrock carb

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I recently puchased a 68 Camaro 350 Th350. It has stock intake, Edelbrock 4 barrel carb which looks to be brand new. Car was driven in Nevada thin air, but I live at low elevation so I think it
needs a carb adjustment. It's been a lot of years since I tried to adjust a carb, can anyone give me the basics? It has 2 adjusting screws facing front of engine-- how do I know if it is running too rich or too lean? Car idles fine but accelarates unevenly, plugs are new & all firing. Any input is appreciated-- Thanks, Terry
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The screws you descibe are for idle adjustment, they will have no effect at higher RPM. You need to change main jets and/or metering rods. Metering rods may do it, and they are accessable from small covers in the top of the carb. Greg
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Greg, ok, I think I remember doing that a long time ago, my only experience with carbs is the old Rochester Quadrajets. But how do I know if it's running too rich or too lean? Should I try various settings, trial and error, or just take it to a mechcanic to have it fine tuned? I'd rather work on this car myself than pay a garage-- thanks for your help, Terry

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I just took the Camaro out for a drive on the highway, it misses pretty bad over 55 mph, maybe it is running too lean. I'll have to check the timing too. I just purchased this car a couple weeks ago, so I haven't done much besides put in a new set of spark plugs.
-- Terry M.
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Take a look at your spark plugs. If the insulators on the tips are yellow and glazed looking, then you are lean. If they are black and sooty, too rich. white to light tan is just right. - Gary

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OK I'll let 'er cool down and then pull a spark plug.....

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OK, I pulled a spark plug, it has very light grey coating. Looks pretty normal to me, definitely not too rich. There's a little engine oil on the spark plug threads too, but none on the exterior of the head-- is it a sign of trouble? I'm no engine mechanic so I'm not sure how to interpret this. Thanks guys for your help, Terry
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My .02:
Throw out the Eldebrock knockoff of the real thing---the Rochester Q-jet.
The Q-jet is far superior to any knock off of itself and superior to most carbs out there for almost all the street apps.
Eldelbrock makes that fit anything. Rochester makes it fit THAT thing (provided you use the original #s matching carburetor).
There's no need to deviate from what the General put there originally :). Joe--ASE Certified Parts Specialist & 10th Ann.Club Tech Director '80 Carousel Red Turbo T/A, 26k orig. '79 "Y89" 400/4 speed 10th Ann. T/A, 57k orig '84 Olds 88 Royale Bgm 2 dr, 307 "Rocket" (lol), 141k and still going.... '80 T/A project car...
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Doesnt Edelbrok now own the rights to all the Qjet carbs? They build a damn fine one at that. Their universal spreadbore carbs are junk, but not the Qjets.
http://www.edelbrock.com/automotive/carb_qjet.html
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Magnetti Marelli bought a lot of old Rochester Products tooling---they do other fuel products that RPD did previously.
First:
There are reasons Rochester Products released all those original tag #s. Each one is calibrated for a specific application.
If you look at their listings, there's a ton of OEM tag #s covered by one carburetor. NOPE.
Each one of those tags varies in:
a) control parts (choke stats pull offs) b) Metering rods c) Internal float bowl differences d) Linkages/intended applications.
Mixing and matching them under one # is a big no-no since it's doubtful Edelbrock determined compatibiliy on a calibrated bench or other flow device like RPD originally did. It's also doubtful that the original parameters of the engine it was intended for were adhered to.
A 1977 400 T/A carburetor would fit and work on my 1979 Trans Am, but 1979 has a specific tag # that is ONLY good for and used in 1979. There are subtle differences between 17059263 on my T/A and the 1978 version of 17058263 used on many 1978 W72 cars.
Most folks make this harder than it has to be. Take the STOCK part and tweak that. You'll be miles ahead.
Just ask Doug Roe and Nunzi Romano---both of them are known carburetor tuners and advocates of the Q-jet.
MILES ahead of anything out there. So much so that Ford and Chrysler saw fit to use it on their engines :).
Joe--ASE Certified Parts Specialist & 10th Ann.Club Tech Director '80 Carousel Red Turbo T/A, 26k orig. '79 "Y89" 400/4 speed 10th Ann. T/A, 57k orig '84 Olds 88 Royale Bgm 2 dr, 307 "Rocket" (lol), 141k and still going.... '80 T/A project car...
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Plugs look ok, plug wires look new, dist. cap looks new. Here's what happens: car idles ok, a little miss. When I drive and accelerate slowly, car misses and sputters, with medium acceleration it's worse, sounds like it might die but doesn't. If I floor it and open up the 4 barrels, car accelerates fine, really takes off....anyone know what might be causing this? Since the carb is brand new, I'm not sure what step to do next.
Thanks everyone,
Terry M.

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Sounds like lean mid range to me. You may need to put richer metering rods in the carb. Full throttle sounds like it may be ok, so the jets themselves are ok. Greg
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Greg, I think this carb might be running lean just like you said. I took the car in to a speed shop that specializes in Chevys (Corvettes) and that was the first possibility that they mentioned. The car was driven in Nevada so re-jetting the carb might do the trick--- Terry

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Sounds like a possible accelerator pump problem to me. Take the air clean off and with the engine not running and cool, operate the carb a few times to wide open position and loof for a steady stream of gas flow.

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-- I just tried this, and yes there is a good gas stream going into the carb from both barrels-- Terry

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Here's a link to the manual for the Edelbrock Performer carb:
http://www.edelbrock.com/automotive/eps_intro.html
If you are going to tune the carb, you might have to buy a calibration kit to richen the primary circuit. The calibration kit comes with jets, metering rods and metering rod springs of various sizes.
Are you sure you don't have a vacuum leak?
Dave
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Dave, I've looked over the vacuum lines, all looks ok. at full throttle the car accelerates real well, but at less than full throttle it still stumbles--Terry

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Have you put a vacuum guage on it? Checked the vacuum advance on the dist. and other vacuum diapham devices to see if they are leaking?

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Bad accelerator pump, vacuum leak somewhere, fuel problem, airflow restriction?
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I've been checking all these things. Since I don't drive the car in the snow anyway, I brought it to a Chevy speed shop in Minnesota, they're going to fine tune the engine, most likely needs re-jetting since the car was a west coast car and I live in the midwest--
Thanks everyone for all the good advice, Terry

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