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Tech Review—Edelbrock VRS-4150 Carburetor

Posted By: Evan J. Smith
Tech Review—Edelbrock VRS-4150 Carburetor
By Steve Turner
Photography courtesy of Edelbrock
While it might seem like the whole performance world is going high-tech with fuel injection, there is still room for innovation in the carburetor space. To serve those bleeding-edge street/strip performers who love to run with old-school induction, Edelbrock developed a modern answer that delivers racy performance with streetable functionality — the VRS-4150 Race & Performance Carburetors.
“You know we’re really proud of this because for 30 years Edelbrock has been the solution for hot rod carburetion and now we have something that's truly a race carburetor that’s street friendly,” Brent McCarthy, Product Line Manager - Intake Manifold / Carburetor at Edelbrock Group, said.
Designed for tunability and flexibility, these carburetors are based on one-piece cast-aluminum bodies that bolt to 4150 and 4500 manifold flanges without adapters. 
“So our main body is one ½-inch taller than a standard carburetor. Another interesting feature is how the boosters are installed in the main body so the boosters drop in and a pin holds them in place and seals them off, so you can change your boosters now if you want to go to a smaller booster or a non-annular or whatever. In our 750, 850, and 950 carburetors, we have a 600-thousandths-diameter annular booster so the annular booster is for better cylinder-to-cylinder distribution that will be standard in our 750-, 850-, and 950-cfm carburetors going to the top of the body,” Wesley Cameron, Product Development Engineer at Edelbrock Group, detailed in a video primer on these carbs. “There’s of course screw-in jets for the four circuits there are interchangeable tunable pump squirters, and tall vent tubes as we go around to the side of the body, we've got auxiliary air bleeds on both sides so these screws allow adding more air to your idle instead of drilling the throttle blade so in the old days we would drill throttle blades for large-camshaft engines now you can just adjust these screws without taking the air cleaner off…”
Available in a wide range of flow ratings, including 650- (PN 1306), 750- (PN 1307), 850- (PN 1308), & 950-cfm (PN 1309) units, the VRS-4150 is suited to a wide range of performance levels, but sports several features suited to dialing in a car that runs on the street and at the track.
“Our fuel bowls have full fuel inlets. They are larger capacity than a standard
fuel bowl,” Cameron explained. “As the fuel enters the bowl, it hits the anti-slosh mustache and as you're driving around and fuel is sloshing in the bowl it comes in contact with all these baffles that are anti-slosh baffles going around the outside of the fuel bowl. It's got a drain plug. It’s also got dual sight glasses on both sides so you can set your float level.”
Those fuel bowls are 20 percent larger and are designed with internal ribs to reduce slosh and baffles that direct fuel and reduce aeration. Even the fuel floats are optimized with corner cuts and jet-extender notches to reduce starvation under high-g loads as experienced during hard launches or cornering.
“The float is notched for the jet extensions. It’s also got the corners notched off for hard cornering so as you go into a corner with a carburetor, the fuel sloshes to one side of the fuel bowl,” Cameron explained. “With these notches that allow this float to drop down and fuel to enter the bowl and fill it back up to avoid fuel starvation.”
To help rein in aggressive, low-vacuum cams, the VRS-4150 carbs are engineered with an advanced idle circuit featuring interchangeable discharge jets at each corner. These allow for dialing in a smooth idle, while the carb’s adjustable intermediate fuel circuits can sharpen the throttle response. 
“...Our full throttle circuit is split into two and we've also got an idle and
intermediate circuit jets pretty much feed every circuit of this carburetor, so there are screw-in jets for the idle and transfer slot fueling. There’s a screw-in jet for the intermediate circuit fueling there are screw-in jets for all the emulsions under the power valve. There are screw-in jets for the power valve fueling, so now not only can you size your power valve for vacuum but you can also jet the fuel accordingly for your wide-open throttle fueling on the wet side of the metering block,” Cameron said. “There are jet extensions on the secondary side there are fuel jets for the intermediate circuit, so these are the feed jets and there’s also an additional idle fueling jet so if you need more fueling in your idle and transfer slot than the main circuit is providing you can add additional idle and transfer slot fueling.”
With plenty of airflow, fuel flow, and adjustability, the VRS-4150 is also easily adaptable to most combinations thanks to thoughtful provisions, like an integrated throttle-position sensor mount.
“…We've got a provision for a GM TPS so if you run an automatic transmission that needs a TPS sensor, you don't have to run a linkage off of your primary throttle arm or anything like that just bolt it directly to the carburetor body speaking of the primary throttle arm ours has provisions for TV cable kick-down so that’s all street-friendly features as we go to the bottom of the carburetor body,” Cameron said. “We've got check valves or check balls for the power valves so in the event of a backfire you don't blow your power valves out ...”
As you can see, Edelbrock’s line of VRS-4150 carbs is packed with features that make them strong contenders for street/strip machines that play in the Circle D Specialties/TorqStorm Superchargers True Street ranks, as well as full-on race cars that fit in NMRA and NMCA heads-up and index categories.
Carb Features
Featuring one-piece, cast aluminum bodies, Edelbrock’s VRS-4150 Race and Performance Carburetors are built to excel in race environments, but offer the features and adjustability to flourish in street environments as well. The body features an external idle-air adjuster screw on both sides that enables tweaking the idle speed without moving the throttle plates.
The billet four-fuel-circuit metering blocks utilized on the VRS-4150 offer precise tuning capability with screw-in emulsion bleeds and four-corner idle-mixture adjustment.
Fitted with 20-percent-larger fuel bowls with internal ribs that tame fuel slosh. These bowls feature -6AN fuel inlets that are swappable to either side to facilitate installation in any arrangement. For convenience, the inside of the bowls is visible via non-staining borosilicate glass sight windows on both sides. They are also machined with bowl-drain screws that are easy to reach and remove.
With levels externally adjustable, the VRS-4150 floats feature corner cuts designed to supply ample fuel flow and jet extenders that ensure there is no fuel starvation under high-g loads, like launches or cornering.
The VRS-4150 carbs are built with a dual-pattern flange, that bolts to 4150- or 4500- flange intake manifolds without needing an adapter. Its ½-inch-diameter throttle shafts are PTFE coated for longevity and friction reduction, and the primary and secondary power valves feature blowout protection. These carbs are equipped with 30cc or 50cc accelerator pumps depending on their flow rate.
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