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#1
08-02-2006, 11:47 AM
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My almost new carb is running rich
I have a '78 Firebird Formula with the 403 and when I bought the car (about 6 months ago) the owner had just put a new edelbrock #1411 750cfm carb and performer rpm manifold. I didnt notice it when I first bought the car but I now know this thing is running way to rich and killing my gas mileage. After warmed up it usually takes alot of pedal pumping and alot of turning over to get the car to start and when it does start I see alot of black smoke from the tailpipes (just on startup) when Im driving I dont see any smoke but whenever I floor it, it usually hesitates or falls on its face...I have no idea how to tune the carb. Ive heard of kits that you can use?? or Ive heard you mess around with a couple screws on the carb?? How do I get this thing running leaner?????
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#2
08-02-2006, 04:22 PM
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I assume you have the original carburetor. It is not going to do you any good to just tell you how to tune a carb. You need to learn what all the adjustments do and what they are for first. You need to learn how the carb works before you can really tune it.
So, unless you have a spare carb lying around for you to take apart and investigate, you should buy one of the several books on rochester carburetors. I don't have a book to recommend to you, but I know that there is more than one out there and they are not hard to find. A good book with pictures will be much more helpful than any forum posts you may read. A spare carb you can take apart is also invaluable to learning it's operation. |
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#3
08-02-2006, 05:11 PM
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I said in the first post that this is the edelbrock 750 cfm carb part #1411, And its just about a half a year old
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#4
08-04-2006, 01:57 PM
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Wow, that was dumb of me. I just assumed it was a quadrajet because a carb such as a holley or edelbrock should have plenty of documentation available on the web or otherwise to answer such a basic question.
Sorry about that. You should still read up on your carb tho. |
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#5
08-09-2006, 08:38 AM
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Quote:
http://www.edelbrock.com/automotive_...f/carb_faq.pdf For starters, make sure you don't have a vacuum leak and that your vacuum lines are all connected properly. Low vacuum can cause the car to run rich by causing the power valves to open at idle and dump fuel. At least that is how the Holley's work and probably the Edelbrock's too. |
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#6
08-10-2006, 04:00 AM
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I think it needs a smaller carb......assuming that the engine is stock, or mildly built it doesnt really need a 750.
A 403 even running at 100% volumetric efficiency would only need a 670 at 5750 RPM........a stock or mild engine wont get 100%. Heres a link to a calculator............most stock engines are well below 100% volumetric efficiency. http://www.4secondsflat.com/Carb_CFM_Calculator.html 750 is too much for that engine.........probably washing the cylinders down with gas......not good. Does your oil smell like gas? Last edited by Colin; 08-10-2006 at 04:32 AM. |
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#7
08-10-2006, 04:33 AM
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Quote:
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