On my 388 SBC stroker in a 6300 lb 1977 chevy silverado i run an AFB Carter Carb it has mechanical secondaries i believe, do any of you like these carbs?...or am i killing my engine by owning one of these.........
its a beefed up version of the 1/2 ton longbed reg cab i believe they actually called it a 5/8 ton or heavy half or something of that matter on the door jam sticker it says it weighs 6300..i assumed GM wouldnt lie to me lol
ok guys i apriciate it, thnx i guess its just a problem with mine is there any special method to tuning one b/c i cant seem to get this one tuned right....? no matter how much i turn the screws in any way the motor runs the same.....it also trys to die if i ease into the throttle it will stay running if i punch it though......any idea's there?
If its an early AFB there (with no idle stop screw) it can be a ****** to tune. They are mostly set up for their original configuration and not much else. They had two fuel mixture screws and one big idle air bleed screw. I had one on a 66 Pontiac 389. After I altered it with an RV cam it never would idle right
Later ones (sometime in the 70s) they went to a more typical idle setup and they are much more tuneable.
i just spent over $180 havign the carb totally rebuilt last year, there shouldnt be anything wrong with it.......other than the fact i suck at tuning them.....i can build engines all day long but i dont really know how to tune a carb....
I'm just getting to that point myself. I just finished building a Qjet. The previous owner had taken the choke off entirely and rigged up a bicycle cable to the dash to manually operate it. I had to find a fast idle cam and then fabricate 3 linkages for the vacuum brake and one link from the divorced choke to the choke bell. Talk about learning curves
The two best pieces of advice I got were; use common sense, and wait. I used to get frustrated because I'd turn the idle needle a half turn and nothing would happen to the vacuum gauge so I'd turn some more. Eventually I got frustrated and started chasing my own tail. That's where the wait part comes in. Make an adjustment and then wait 30 seconds for it to stabilize.
The two best tools I found for tuning a carb are the papers that come with the rebuild kit, and the shop manual for your vehicle. They have all the tune-up specs and bench settings. Then using some deductive reasoning start changing things in the direction you think they need to go.
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