better idle, still a bit rich tho. Of course, this is also the perfect time for perhaps a upgrade or two to make the carb work as good as it will now look. If the engine decreases rpm when you are adjusting the others, take them all back to the original setting, because the settings were already correct. Airflow down through the venturis (and boosters) creates low pressure that pulls fuel from the fuel bowl through the main jets and into the airstream. Keep in mind that the jet sizes, power valve and accelerator pump adjustments that provide the best performance today may not produce the same results tomorrow. But don't despair if you have a Holley with straight boosters. Once you understand them, you can spend many enjoyable hours perfecting the fuel curve for your engine combination. Holley makes several kitsmainly for either the 0-3310 750 cfm or the 0-1850 600-cfm carbs. The first step is to obtain a low-speed tach that will show minor changes in rpm along with a vacuum gauge. The volume of the pump, the shape of the cam and position of the linkage that operates the pump, and the size and position of the discharge nozzles all affect how much fuel is delivered when the throttle opens. The conventional fix for big-cammed carbureted engines is to drill holes in the primary and sometimes in the secondary throttle blades near the transfer slot with sufficient size to allow closing the curb idle adjustment back to its ideal location. So, you might want to check your air/fuel ratio at cruise with one of the many hand-held air/fuel ratio devices or gauges currently available. This Holley Ultra XP and some older HPs employ a bypass idle circuit with an adjuster screw located underneath the air cleaner stud mounting boss. But if its a used carburetor, beware because a lot of unpleasant surprises can be lurking inside: The bottom line is you need to make sure the carburetor youre going to use is in good working condition and hasnt been screwed up, otherwise you may never get it to work well. Another indication if the main jets are correct is how the car drives. Rusty but Rare 1976 Chevy K10 Sport Truck Revival! Reading the spark plugs can also give you a rough idea of whats happening to the A/F mixture. Quick Fuel Technology Carb Install and Tuning Walkthrough - YouTube Will put my AR3924 plugs in it, bump up the initial timing to 20 and see what happens. To access the carb must be inverted. Engine testing all carburetors prior to shipment ensures that when a new QFT carb is bolted on an engine, it will start, idle and perform up to the customers expectations. Holley (QFT) Brawler 570 tuning - racingfuelsystems I road race mine and use it. Many performance carbs now offer four screws but the procedure would still be the same. Marvel at the beauty of a carburetor in its natural habitat onboard a large displacement American V8, this one under the hood of the Holey Goat 1970 Pontiac GTO. Engine setup is a 72 block zero deck kb flat top bottom end. We wrote the first of many electronic fuel injection stories way back in 1988 in which we proclaimed that the carburetor, if not dead, was on the clear path to antiquity. I just cant see a little bit of vacuum advance fixing this tho. Lightly clamp the steel diaphragm shaft in the vise. This includes the choke, fast idle cam and linkage, and fast idle adjustment screw. Black carbon deposits on the center insulator and electrodes would indicate an overly rich A/F mixture (or the spark plugs are too cold for the engine). If the secondary throttle opens to soon, the engine is more likely to bog. I've been reading through posts and I might be in too deep, but I'm determined to get her running right. As part of our small block Ford build, we decided to use Holleys Terminator X EFI system for plug and play Ford V8 engine control. Cold start circuit. Save my name, email, and website in this browser for the next time I comment. Mine didnt smell rich, the plugs were just super soot filled. Automatic choke problems can also cause hard starting, cold stalling and idle speed problems. It can replace Holley, Edelbrock, Carter AFB, and Autolite style carburetors with 5 3/16 x 5 5/8 bolt pattern. Are the fuel bowl inlet valves in good condition and not sticking or leaking? The first step is to obtain a low-speed tach that will show minor changes in rpm along with a vacuum gauge. But there are a couple of other points worth mentioning. At idle, there should be zero clearance or even a slight preload between the linkage and the actual diaphragm. lowered idle back down to 1,000 rpm. Vacuum secondary carbs control secondary opening with venturi vacuum opposing a diaphragm and spring. We feel you have purchased the finest street performance carburetor currently on the market. This engine, named as part of the X engine family, is uniquely positioned to replace both the L9 and the X12 with the versatility to serve both medium and heavy-duty applications. If the carb has a choke, preset it to the 0 or midpoint setting. Heres a quick how-to that covers installing a new Holley Brawler double-pumper carburetor. Tools Bible is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising & linking to Amazon properties. carburetor tuning and adjustments tech Quick Fuel Technology (QFT) ships carburetors only after they have been thoroughly run-tested and adjusted on a typical engine. 15 degrees of timing at idle and 34 total, do not have the vacuum advance hooked up. MSD 8365 ditributor, coil, 6AL2, 8.5 wires, everything is new and works. Except Im running a single plane. was thinking about putting my 1" open on it just to try. Brawler carburetors are precision-machined and hand-assembled by craftsmen right here in the USA. So instead, we focused most of our time on street driveability. In this photo note the Holley in the foreground has no ledge compared to the main body on the far right with the small ledge just above the main metering block mounting surface (arrow). Murphy machines all this carb bodies to ensure they are flat. The pump squirts additional fuel into the throttle bores when the throttle opens to compensate for increased airflow. Understanding Ignition Timing: Making Maximum Carburetor Tuning For Performance and Restorations. The change from 6.5" to a 5.5" power valve will most likely be too narrow a change, I'd drop to a 4.5". Find Best Carburetor for Small Block 400 and about 400 sbc carb size. After a long stretch of steady-state highway driving pull off in a rest area and check the tailpipes. curious how much advance they give. This is Holley's TPS conversion bolted to a 4160 Holley with an electric choke. Dual inlet fuel bowls are not included in the kit but you can add them at the same time. Murphy brought it right back to life with a rebuild and a dip in his acid etching process that makes it look like new. Adjust the linkage on the accelerator pump so that the instant the throttle moves the accelerator nozzle will squirt fuel. Before the engine starts, check the position of the idle mixture screws (located on either side of the metering block) by counting the turns on each one in until it lightly seats. For this procedure we'll assume a Holley with only two idle mixture screws. endobj It's also possible to slightly increase the secondary throttle stop to slightly increase airflow but again only enough to avoid opening into the secondary transfer slot. We went to Zach Baker, a technician at QFT that spends much of his time talking customers through the correct tuning procedures, to give us his proven step-by-step carb tuning tips to get the most out of your carburetors performance. Heavy black soot in the exhaust or tailpipe would also indicate an overly rich A/F mixture. % Some Holley tricks don't have to relate to performance. Holley Brawler Carburetor Installation How-To and Basic Tuning - YouTube 0:00 / 5:23 Holley Brawler Carburetor Installation How-To and Basic Tuning Pole Barn Garage 68.5K subscribers. For street cars, depending on the vintage of the vehicle and state laws, a carburetor may have to be emissions legal. That means vacuum hookups for the PCV and EGR valves, a choke and possibly restrictors for the idle circuit so the carb doesnt run too rich and increase emissions. 4 0 obj A set of calibrated pin vises really helps dial in restrictor sizes. What size carburetor do I need for a 400? Murphy prefers later-model boosters with the gentler radius at the bend that improves flow and its inside diameter is slightly larger at 0.160 inch versus stock at 0.140 inch. Brawler carburetors are loaded with the latest technology in air fuel calibration to meet the demands of todays street, strip, and race engines. The Brawler family of carburetors are all made from light-weight aluminum components and are available in both vacuum and mechanical secondary models. We'll work to keep you motivated and informed and with industry news, product information and reviews, event coverage, and well-curated articles and stories intended to inspire and educate. Trial-and-error changes to the accelerator pump and/or main jets and/or power valve should eventually sort out the problem. EFI has many advantages thatallow us to dial in the fuel in a dramatically more precise fashion than was ever possible with a carburetor. We planned to use the AEM Controller Gauge to assist in tuning our 570 CFM Brawler carburetor for power and economy. Wait a few seconds and idle should be exactly 1400. We need to determine the areas of the jets and the power valve restrictors. There is one more adjustment left after you establish the correct power valve opening point. At WOT when the power valve opens, the overall fuel flow would be nearly identical, but with this combination the part-throttle air/fuel ratio (before the power valve opens) would be leaner by four jet sizes. Make sure the hole that seals the diaphragm transfer slot is uncovered. Simply as an Amazon Associate, we earn from qualifying purchases. Most QFT carbs come from the factory with .043-.048 power valve channel restrictions. There is a tip-over point between rich and lean where combustion is ideal. 237/ [email protected], 600 lift. thanks. Next time you have set of large journal small block Chevy connecting rods to resize, consider honing the big ends of them for a +.002 outside diameter bearing that the LS engines with fracture cap rods use. This, in turn, tells you if you need to richen up or lean the main jets and/or change the power valve to correct the A/F mixture. Automatic chokes are supposed to make cold starting easier, but usually require some trial-and-error adjustment to find the best setting. Big cams like a lot of initial, always use he vacuum advance. Be careful here to not catch the rubber with the threads of the screws. I looked last night but cant find my dyno sheet. Tuning The Brawler Carb | Small Block Chevy 327 - YouTube I want to do a little testing to see how much hooking up the vacuum advance actually advances the timing over the baseline. If larger jets hurt performance, go the other way and decrease the size of the jets until the engine feels stronger. The crew shows how to save cold-hard-cash by overhauling an Edelbrock AFB-style 4 barrel performance carburetor. The carburetor will also deliver the optimum air/fuel ratio throughout the engines RPM range to achieve peak horsepower and torque. Start each screw by hand as the lid is held in place on the diaphragm. Another check to make before you start playing around with the jets, accelerator pump and power valve is the fuel level inside the fuel bowls with the engine idling. The 3rd phase of new Brawler carburetors build on the success of the originals by adding more CFM sizes & a black coated finish with red billet metering blocks & throttle bodies. By comparison, race carburetors are purpose built for specific applications. Best Tuner for 6.0 Powerstroke [Review and Buying Guide]. Inside the fuel bowl is a brass, hollow plastic or foam plastic float that maintains the fuel level. Drivability is just as important, and that requires a lot of air velocity for instant throttle response and good low to mid-range torque. Brawler carburetors are precision-machined and hand-assembled by craftsmen right here in the USA. I use vacuum advance on all the builds I do, I build limiter plates to keep the canister at 8-10 vacuum adv max. Brawler carburetors are precision machined and hand-assembled by craftsman right here in the USA. revs quick and starts right up and idles whether its cold or at running temp. Let's say that the left side is three-quarter turn out and the right is one-and-a-half turns out. To support the popularity of the Brawler carburetor it seems only natural to add rebuild kits and tuning parts for them. Adjustable tapered idle screws for each barrel control how much fuel is pulled into the engine at idle by intake vacuum under the closed throttle plates. In case you're taking notes, the secondary metering block is the main difference between 4160 and 4150 carburetors. HGM's AccuLink is a very slick stainless steel conversion kit that adds a GM-style TPS sensor to all popular Holley, Q-Jet, and Edelbrock carbs. I do have the dyno sheet somewhere at the house, have to look tonight. my concern is the 39* of total timing it has, this was all in by about 2600 rpm. This means we have to increase the PVCR by the same area, which came out to very close to a 0.062-inch restrictor. In fact, the HGM AccuLink is designed to work with Holley, Q-jet, and the Edelbrock carburetors. 1 change at a time. Understanding Holley Vacuum Secondary Carburetors, How To Choose A Regulator For Carbureted Vehicles. x\r6N xt:[;N;&kEDL$Jdp}'dlPs[$>f?o} s]b8?e.w@!YKM~RL?`S,l:? Vintage 1980 Yamaha Enticer Snowmobile Revival to Former Glory. 540hp small cubic inch and close to 600hp with 400 cubic inch, all on pump gas. Find many great new & used options and get the best deals for Quick Fuel Technology BR-67212 Brawler Street Carburetor at the best online prices at eBay! So the first tip when looking for the head waters of a problem is to make sure the ignition system is in a good state of tune, the engine is physically in good shape, there's decent fuel pressure, and there are no vacuum leaks. Generally these restrictors are permanently drilled passages in the metering block. If the carb will be subsequently used on a milder-cammed engine, it will probably not be possible to return the curb idle speed low enough because of the permanent holes. This is Murphy's custom booster install tool that accurately positions the booster and flares the inlet in the main body flange. The basic difference between a carburetor and electronic fuel injection is that a carburetor is totally dependent on intake vacuum for fuel metering and delivery. The way to do this is to have your vehicle on level ground and with the engine running at an idle. Let's say you have a 750 double-pumper Holley 0-4779. You can call me gearheads or petrolheads. The engine should be turned off while you are setting the adjustment on all of the screws. It is worth mentioning that the fuel pressure gauge should be installed on the outlet side of the regulator as close to the carburetor as possible. Hollow metal and plastic floats can leak and foam plastic can absorb fuel. Theres no choke to restrict airflow into the carburetor, and the venturis, boosters, metering blocks, fuel bowls and throttle plates may all be heavily modified to deliver the kind of performance a race car driver expects. Changeable idle & high speed air bleeds for easy tuning . The booster in the background is an original drop leg from an early Holley. Regardless if you have a two- or four-corner idle adjustment on your QFT carb, start by setting all of the idle adjustment screws the same (1-1/4 turns from bottomed out in the metering block is a good place to start). There may be dirt or corrosion inside that can plug circuits and restrict fuel flow. If you need a minor adjustment, be sure to shut the engine off and go through the adjustment procedure again. These are dropped boosters that have been used on performance Holleys for decades. This is the idle stop adjustment for most Holley carburetors. A yellowish or blistered appearance on the spark plug electrode would tell you the A/F mixture is much too lean (or the spark plugs are too hot and the engine needs colder plugs). A power valve that is too small may not increase fuel flow enough under load, causing the A/F to go lean. But if your vehicle has an adjustable pressure regulator, set it for the ideal 6.5psi. Finally got it running much . Many. The conversion kit (foreground) replaces the metering plate like on the 4160-style carb on the left and replaces it with a metering block like the 4150-style carburetor on the right. Set the idle mixture for the best idle quality along with the leanest air/fuel ratio. To improve our situation, we contacted the officials at Brawler about a four-barrel (4bbl) carburetor to replace the restrictive 2bbl. Was nowhere near close out of the box. Manual chokes require no adjustment but do require a certain amount of finesse when it comes to starting a cold engine. Brawler BR-67255 Carburetor, Mechanical Secondary, 650 CFM (7) Carburetor Barrels: 4-Barrel. Okay, now comes the fun part. If the carb has screw-in fuel filters, are the filters clean and unobstructed? Available in both vacuum and mechanical secondary versions to meet your needs, All models have dual inlet fuel bowls with sight glass windows for safe and easy float adjustments, All models come with an electric choke for easy starting in colder climates.