There’s no disputing the great success of Edelbrock’s time-proven Performer Series carburetors, which are simple to service and tune thanks to innovative architecture that has been around for decades and has been improved with continual development work. Edelbrock has taken this design and weaved its own brand of engineering into an already-terrific carburetor.
A good many of these Performer Series carburetors are becoming long in the tooth and are ready for restoration. This tells us these are pretty reliable carburetors because they rarely need service. They’re that good. When they do require service, it’s nice to know they’re easy to knock down and service in your home garage.
We decided to drop in on Ted Granger and his son Dustin at Ted’s Carburetor Service in Lancaster, California, to see what they could do for a decidedly worn-out and crusty Edelbrock Performer that was no longer performing up to par. What surprised us is what Ted and Dustin said about carburetors in general. Both commented that fewer and fewer people know how to service and tune carburetors in this largely fuel injected age. When people can’t get a fault code or turn the key and play immediately, they freak out because they don’t know what to do with a carburetor. However, Ted and Dustin know exactly what to do.
Our Edelbrock Performer 600-cfm carburetor (PN 1405) suffered from harsh California fuel additives and steady, daily operation. It needed a complete rebuild and tune. Dustin is all too familiar with the Edelbrock Performer as well as the Carter AFB because both are quite similar in design and function.
He gives the Edelbrock Performer carburetor high marks for durability and great turnkey performance. However, today’s harsh fuel additives, Dustin stresses, can wreak havoc on a carburetor’s tender insides and negatively affect performance. Critical passages—especially those in the boosters, air bleeds, and accelerator pump nozzles—tend to get blocked with debris, adversely affecting function.
Where the Edelbrock Performer carburetor differs from its competition, be it the AFB or the AVS, is how fuel is metered and delivered. Step-up fuel metering rods and pistons regulate fuel delivery based on intake manifold vacuum and piston spring pressure. Fuel metering rods and jets come in various sizes depending on what you want your Performer carburetor to do.
The Edelbrock Performer employs an extremely finite system of fuel management. The primary jets are larger than the secondaries because the metering rods are used on the primary side. This makes the Performer different than other four-barrel carburetors where the secondary jets are larger. With the Performer and its Carter AFB/AVS counterparts, the primary jets provide fuel for idle and the majority of part-throttle action.
The metering jets are accompanied by two-step metering rods, which are used to control fuel flow on the primary side. The larger diameter of each metering rod is positioned in the jet at idle and minimum throttle when intake manifold vacuum is strongest. As the throttle is opened and manifold vacuum falls, the metering rod lifts and the smaller diameter moves into the jet, allowing greater fuel flow.
Performer and AFB/AVS jets are normally stamped with the jet part number. The 120- is the part number and the last three numbers are jet size (e.g., 389 = 0.089-in., 401 = 0.101-in., etc.). If you cannot read the jet size, use a drill bit to measure its size. Because metering rods can be swapped without taking the air horn off, they are often the better choice when trying to adjust out from a lean or rich condition. Change the metering rod one size at a time until you get what you want.
If you don’t achieve the desired result in terms of performance and driveability, consider a jet swap. Mike’s Carburetor has something to add to the discussion when it comes to the Edelbrock Performer and its Carter AFB/AVS cousins. In order to achieve the correct jet and metering rod combination, subtract the total metering rod size from the swapped-in jet diameter, which will then give you the correct metering rod diameter. Jet size is .098-inch and the metering rod is .076-inch. That winds up .098 - .076 = .022. To go leaner, you opt for a jet size of .096-inch; meaning .096-inch minus .022-inch equals a .074-inch metering rod size.
Mike’s Carburetor, which offers the enthusiast an extensive array of Performer parts, adds the exact area of calculation would get you a .068-inch rod size. During part throttle, light cruise operation manifold vacuum overcomes the tension of the step-up piston spring and pulls the step-up piston and assembly down, holding the large diameter of the step-up rod in the main metering jet below. Fuel then flows through the jet and around the metering rod at a reduced volume.
During acceleration and under a load, spring tension overcomes manifold vacuum beneath the step-up piston. As a result, the step-up rod will move up to where its smaller diameter, or power step, is in the jet. Fuel then flows through the jet and around the metering rod at a higher volume. This makes the Edelbrock Performer’s fuel metering linear to where fuel delivery follows throttle position and engine load.
Basic carburetor architecture is what makes the Edelbrock Performer carburetor so terrific. They are easy to service and tune on top of your engine. We caution to always keep track of small parts whenever your Edelbrock Performer is mounted on the engine. Small items like clips, screws, and check valves can fall into the intake and then you have a new problem you don’t want on a Saturday afternoon.
1. Ted’s Carburetor Service is tackling a particularly nasty Edelbrock Performer carburetor that served us very well for many years. When it was tossed on the shelf, California fuel additives took their toll during a long sit. Dustin Granger is going to knock this Performer down and treat it to an ultrasonic cleaning.
2. Dustin begins with a penetrant to prevent screw breakage. It is always a good idea to let a carburetor soak in penetrating lubricant before disassembly if it has been sitting for a long time. Remember, when you store a carburetor make sure all the fuel is drained and the passages are coated with WD-40.
3. Disassembly begins with disconnecting all the linkages that connect the air horn to the main carburetor body. Take pictures and keep close track of all the hardware.
4. Remove all the air horn screws and put them in a safe place. Magnetic parts trays from Harbor Freight are great to have on hand to keep the parts from wandering off.
5. Beneath these two covers are the step-up pistons, which do more or less the same thing a power valve in a Holley 4150/4160/1850. In the Edelbrock Performer Series carburetors the step-up pistons function via manifold vacuum to meter fuel delivery as the throttle is opened and more power is needed. The primary jets provide fuel for idle and most of the part-throttle transition. A two-step metering rod is used to control fuel delivery on the primary side. As the throttle is opened and manifold vacuum falls, the metering rod lifts and the smaller diameter in the jet allows more fuel to flow.
6. Once the screws have been removed and the linkages disconnected the air horn can be lifted off the main body.
7. This is one of two step-up pistons located between the primary and secondary bores. Step-up pistons control fuel metering “step-up” rods via intake manifold vacuum for fuel enrichment. The step-up pistons are spring-loaded and vacuum actuated. Metering rod and jet sizing is everything to performance. Determine which metering rod and jet sizes are right for your application. An incorrect step-up piston spring or using a spring that has been stretched out of shape will cause poor carburetor behavior at low and high speeds. Invest in a complete set of step-up piston springs and learn how to tune your Performer.
8. The step-up piston and metering rod work together to adjust fuel metering through the jet screwed into the fuel bowl (arrow). Intake manifold vacuum works against spring pressure to keep fuel flow linear as power is needed and not needed.
9. These tiny passages are idle passages controlled by the idle mixture screws.
10. If you work with a lot of carburetors, you’re going to want one of these. This is a Dzus fastener screwdriver, which is used for Dzus fasteners on aircraft and race cars and is available from any aerospace tool outlet. The wide blade makes light work of carburetor service. What’s more, these drivers are cheap at around $5-$15.
11. Setting the float level is easy on the Edelbrock Performer. Edelbrock suggests you place a 7/16-inch drill bit between the float and carburetor air horn to set the float level precisely. Allow the weight of the float to rest on the 7/16-inch drill bit and that’s where the float level should be. Dustin sets the float level per the Edelbrock carburetor kit, which winds up being the width of a 7/16-inch drill bit. Never press the float needle valve against the seat.
12. We’re working with the Edelbrock Performer 600-cfm carburetor (PN 1405) with a manual choke. This works very well when an electric choke isn’t convenient.
13. Fuel gets to the primary throttle bores via these boost venturis, also known as booster clusters. The booster clusters atomize fuel where it is drawn downward to the throttle plates and into the intake manifold. However, the primary booster clusters do more. The black arrow indicates the primary air bleed that enables the primary booster to draw fuel from the bowl. The white arrow is the primary bypass idle air bleed that helps limit fuel being drawn up to the idle circuit. The red arrow is the idle emulsion tube where fuel is drawn into the idle circuit and the blue arrow is the idle fuel jet.
14. There are two secondary venturi clusters in the Edelbrock Performer carburetor. Unless you’re anticipating significant changes in power, these boosters do not require modification.
15. Accelerator pump operation begins with this link, which connects the throttle bellcrank to the accelerator pump on the air horn. On the Performer carburetor shown, this link connects to the middle hole (arrow).
16. This is the accelerator pump piston, which is blue in color with a plastic stem, included in the Edelbrock rebuild kit (PN 1477). There are a number of different types of accelerator pump piston assemblies available for these carburetors depending upon the type of driving you’re going to do, along with the type of fuel you intend to use. California fuel additives are especially hard on fuel system parts like the accelerator pump cup/seal. Dustin tells us the orange pump piston cups are more resistant to today’s harsh fuel additives.
17. Here’s the accelerator pump nozzle, which should be free of debris and gasket material. Dustin stresses getting all passages completely clear. Fill the accelerator pump well with gasoline or even something like WD-40 and check operation. WD-40 will clear when the engine is started and the accelerator is depressed.
18. Don’t forget the accelerator pump check valve, which allows the flow of fuel to the nozzle, but does not allow flow back to the fuel bowl.
19. Installation of the air horn can get tricky. Make sure you connect the accelerator pump and secondary air valve linkages, then check them for any binding.
20. The Performer has a number of vacuum ports you need to be aware of. First is the PCV valve port, which is the largest. You have the option of capping the front PCV connection off and using the one in back, which eliminates hose clutter. The two smaller ports are throttled vacuum and unthrottled vacuum. Throttled vacuum is for the vacuum advance. Unthrottled vacuum is vacuum all the time for accessories. Don’t get these backwards.
21. An overhead look at the Performer gives you some understanding of how this thing works. The primary throttle bores (white arrow) are what you use most of the time in normal driving. They are complemented with a manual or electric choke with a fast-idle cam for cold-start, high-idle speed operation. What makes the Performer and AFB/AVS carburetors terrific is how they segue into full-throttle, high-performance operation. A weighted secondary air valve allows a smooth transition into the power circuit when the butterflies are pinned wide open. This makes the Performer a natural, well-engineered carburetor because it is so easy to tune and live with.
22. Our Edelbrock Performer Series carburetor was originally clad in a satin finish. The ultrasonic cleaning process turned the satin finish into a cool matte gray finish, which isn’t for everyone. Out best advice is to use a petroleum-based or hot soak solvent for cleaning purposes if you wish to retain the satin finish.
Photos: Jim Smart