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Performance & Hotrod Business May '14

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68 n Performance & Hotrod Business n May 2014 to make the best power. Think of a piece of wire. It has an innate resistance. That resistance is given a number in OHMS. You use amps to push volts through the wire. In an engine you use vacuum created to draw air through the carb's resistance so your engine gets air. In a wire if there are no amps there will be no volts. In an engine if there is no vacuum, there will be no air. If you have a lot of vac- uum, then you will get a lot of air through the same resistance. If your engine creates poor vacuum, then you need to lower the resistance to get more air. Dan Nicholas of JET Performance Prod- ucts mentions the volumetric efficiency fac- tor of engines, pointing out that most per- formance street engines are between 85 and 90 percent and race engines can exceed 100 percent. In addition, when selecting the cor- rect carburetor for a street application, you need to be aware of the type of linkage that is available for the carburetor that you're install- ing. Trying to connect throttle and transmission linkage to a carburetor that isn't set up for your application can be a chal- lenge. No Finger-Pointing Carburetors don't fix other problems. Make sure the rest of the vehicle is in good shape before pointing your finger at the carburetor. Carburetors get replaced all the time only to find out that it's an ignition problem causing the car to run badly. Make sure the problem has been diagnosed correctly be- fore replacing parts. Carburetors are not plug and play. You're not going to just install it straight out of the box and have a perfectly tuned and running engine. Say that three times to remember it. The most common call our manufac- turers face is about a freshly installed carb that does not perform perfectly. Maybe it's flooding. Maybe it's too lean. Don't auto- matically blame the carb before you take the time to tune it and check several other more-than-should-be-normal offenders. Smitty Smith from Edelbrock suggests some possible causes for flooding. One of these scenarios is part of the OE steel fuel line might have been cut off with the wrong tool, and some small metal shavings (barely visible) got into the fuel line. Another scenario is that the fuel line might be hooked to the front port of an Edelbrock style of carburetor, which is not the fuel inlet. This front port is for the PCV valve that has a hose from the front of the Edelbrock carburetor to its valve cover. Another situation that sometimes hap- pens is it will flood after starting the en- gine. He suggests removing the top lid of the carburetor, where there are only eight screws and two or three clips (depending on if it's equipped with a manual or elec- tric choke) and adjusting the float level on the carburetor. Demon's Scott Witmer suggests that the two greatest obstacles amateur carburetor tuners face are failing to understand the es- sentials of initial ignition timing and idle settings. Demon's Carb Selection Guide is designed to help choose the correct carburetor for the engine and how the vehicle will be used. HOTROD CARBURETOR SECRETS Carburetors are not plug & play; you'll need to make adjustments before you have a perfectly tuned and running engine. (Courtesy Edelbrock) PHBMAYp58-91.indd 68 4/2/14 1:56 PM

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