Dual-Feed Carb Conversion

style"text-decoration: underline;"emstrongDual-Feed Carburetor Conversionstrongemspanbr Time: 1 hour (approximately) Tools: socket set, flat-blade screwdriver, small knife or scraper, adjustable wrenches (optional). Cost: (varied) approximately 100-300br Tinware: center-hung fuel bowls (if needed), metering block and hardware (sold as kit), metering jets, replacement gaskets, dual-inlet fuel line. strongemTip:emstrongem transfer the carburetor from the engine to a clean, open workbench. If you dont have a carb stand, simply slide four bolts of your choice through the mounting holes in the bottom and nut them up at the top. All you need is enough clearance for the levers and linkage. (see 1)embr Performance gains: increased fuel delivery and tuning accuracy. Whether youre working with an old factory Holley, or even a fresh, out-of-the box unit, making the switch to a dual guzzler can dramatically boost your carbs No, we am not talking about double-pumpers here. Although they may reign supreme at the track, some of us simply must work with what we have in our at the time, or what has been reluctantly handed down over the years. For most mild street applications, just about any standard 600 or 650cfm carb (model 4150 or 4160) should do the trick, and with minimal adjustment. They were engineered and built mainly for everyday economy and reliability with a little added on the side. True, not a bad route to go for the family truckster, but if youre serious about maximizing your motor to its fullest a definite change or upgrade must be made. Here are some reasons whybr First and foremost, lets take a look at the bowl. Most of the smaller 4160 models share the same design of a side-pivot . Mounted to one inside wall of the fuel bowl, these floats fail to control the level and flow that is needed under hard cornering. Think about it. If centrifugal forces the fuel inside the bowl away from the , the leverage to close the inlet valve is naturally decreased. In turn, this allows more fuel to enter the bowl than is really needed. The same goes for a turn in the opposite direction as well. This time with an increase in leverage, the is tricked to believe there is ample fuel in the bowl causing the inlet valve to close Either way, it makes for a degraded In addition to whole issue, these carbs are equipped with a somewhat and restrictive fuel transfer tube. This small tube carries the fuel from the bowl down the side of the carburetor and into the secondary. On each end of the tube is an O-ring seal. Non-reusable and stubborn to reseat, these gaskets can make something as simple as a jet change a true test of Needless to say, this is about the last thing we care to deal with at the track, or anywhere for that matter! There has to be better alternative. Luckily, there are of upgrade kits available from Holley for just about anything you might be running. The swaps are fast and relatively straightforward. With that said, lets get busy. We selected a stock 750cfm vacuum secondary Holley (model 3310) for the Factory equipped with dual, center-hung fuel bowls, we were only in need of a secondary metering block and hardware (Holley 3413) to complete the conversion. The smaller, models would require the additional of Holley 34-2, which is a of dual inlet fuel bowls and their respective gaskets. a href"http:blog.ecklerscorvette.comwp-contentuploads201508shot1.jpg"img class"alignnone size-full wp-image-2187" src"http:blog.ecklerscorvette.comwp-contentuploads201508shot1.jpg" alt"shot1" "550" height"367" abr emStart by removing the existing secondary fuel bowl (4 bolts). Be careful not to tear the small, circular gaskets behind the bolt heads, as these are to leakage if damaged.embr In our case, we start by removing the rear fuel bowl to access the existing metering If your carburetor still has gas in the bowl, grab a rag or a small catch cap to keep from spilling. Once the bowl is off, carefully unscrew the metering from the carbs main body. There will most likely be some leftover gasket material still stuck on the mounting surface. If so, a small blade or scraping knife should do the job. strongemPlease note: In the next two weve used a different model Holley carburetor to illustrate the change-over. (The carb in these next two was already equipped with a dual-inlet fuel bowl).emstrongbr a href"http:blog.ecklerscorvette.comwp-contentuploads201508shot2.jpg"img class"alignnone size-full wp-image-2188" src"http:blog.ecklerscorvette.comwp-contentuploads201508shot2.jpg" alt"shot2" "550" height"367" abr emWe strongly recommend Holleys reusable, non-stick foam gaskets over the stock ones. Without the hassle of cleanup, it makes like this that much easier. Notice the secondary jets have already been in the block.embr With the new gaskets already installed, the metering block and its jets follow suit and right into Similar to the front system, the addition of this block gives you total control of secondary delivery, and allows you to custom tailor it to your specific application and needs. Using the supplied longer bolts, attach the dual-inlet fuel bowl onto the block housing. Be cautious not to over-tighten and risk the of tearing or damaging the seals. emTip: a good way to keep track of your jet sizes, either front or back, is to write the numbers in a washable marker on your fuel bowl for quick reference.embr a href"http:blog.ecklerscorvette.comwp-contentuploads201508shot3.jpg"img class"alignnone size-full wp-image-2189" src"http:blog.ecklerscorvette.comwp-contentuploads201508shot3.jpg" alt"shot3" "550" height"367" abr emWith everything back in its we now add the new, dual-inlet fuel line. Sure, braided stainless steel might be a little overkill for the low this system will see, but we find it nice just knowing its there, and it looks great!embr Now all thats left is attaching the new fuel line. Regardless of the brand or style, all aftermarket fuel lines are much the same in function, and are made to easily adapt and fit your specific carburetor.