Performance isn’t always about power. If you are a card-carrying car crafter, then the price of fun with cars is a continual balancing act. It’s like the scene in Animal House where the devil is on Larry Kroger’s right shoulder with an angel on his left. The devil urges spending big money on a giant hero carburetor, while the angel preaches restraint. As odd as it seems, we’re reachin’ for the restraint button with a roundup of seven vacuum secondary 750 cfm carburetors that are all priced less than $300.
To evaluate our magnificent seven, we’ve come up with a whole pile of qualifications that will test the entire breadth of these fuel mixers’ abilities. Our favorites are the out-of-the-box horsepower and cruise-rpm air-fuel ratio tests. These are critical evaluations because many enthusiasts can’t be bothered with carburetor tuning. They want something that will run nicely as soon as the last bolt is tight. But we have stuff for you tuning veterans, too, including a cool evaluation of the amount of fuel used for the horsepower produced. Engineers refer to this as brake specific fuel consumption (BSFC). By the time we’ve explained it all, you’ll be able to baffle your future ex-father-in-law with your dynamic grasp of such a complex topic.
Our test subjects run the gamut from the classic Holley 3310C to the relatively complex Quadrajet. We even took a look at a couple of remanufactured carburetors since they offer bang-for-your-buck benefits. Frankly, all the carburetors worked very well, some just a little better than others. We even threw in a hashed, swap meet Holley we bought for $85. And if you’re thinkin’ that we sabotaged that one to make the others look good, well—you’d be mistaken. But enough introductions, let’s get to the good stuff. The only request we have is that you don’t skip to the end—if you do, you’ll miss the important stuff.
If you remember our small-block cylinder head test from last month, then you’ll recognize our budget 9.7:1 compression 350 Chevy still equipped with the same Summit camshaft (224/230 with 0.496/0.517 lift, 114 LSA, Summit PN 1105) and a set of Dart 200cc SHP heads. The intake is an Edelbrock dual- plane Performer RPM and we ran the test with a set of 13⁄4-inch dyno headers with mufflers. We chose this engine because it’s 400hp potential is typical of the average performance engine on the street.
Holley 750 Vacuum Secondary 0-3310-13C
If there is a prototypical Holley street carburetor, this vacuum secondary 750 is it. It’s hard to top the classic image, and its price is equally attractive. As a 4160-style carburetor, it is still a dual inlet, but it replaces the secondary metering block with a plate that shortens the length compared to a 4150 version Holley. Note that this carburetor has a manual choke. We fitted ours with Earl’s -6 male adapter fittings to make the fuel line connections easier. Perhaps its biggest detraction is the secondary metering plate, which requires complete replacement if you want to re-jet the secondaries. But we found a budget way around that, too.
Remanufactured Holley 750 Vacuum Secondary 0-3310-12S
We discovered a remanufactured Holley in the Summit catalog that is $30 less expensive, with the only difference being its shiny exterior. Not seconds, these are carburetors that have been returned (usually after the original owner mangled an adjustment like the float level) and then recertified. As we expected, the carb bolted right on and ran perfectly. Be forewarned that these carbs cannot be returned. It was easy to differentiate the two carbs in our test because the reman came in the Holley shiny “S” version. This carb was also a slightly different model number and performed slightly richer in our tests compared to the new Holley 0-3310-13C.
Swap Meet Holley 750 Vacuum Secondary 0-3310-3
Since this isn’t Fortune magazine, we thought it would be fun to see how a swap meet 3310 would fare. We bought one at the Long Beach Swap Meet for $85 and soon discovered it was missing both primary jets and the secondary needle and seat. After adding the errant parts and new gaskets, it appeared ready for service. That turned out to be wishful thinking because the carb refused to idle. This required a second disassembly, complete cleaning, and reassembly. If you had to pay for this work, Sean Murphy Induction charges $195 for a Stage 1 rebuild, which puts this carb now at roughly the same price as a new Holley. Of course, it you know your way around a Holley 750, then you can save the labor costs, but you still have a carb that looks like it was old when Don Garlits was a youngster. SMI will recolor your carb for another $45 but you still have the equivalent of a Joan Rivers face-lifted carburetor. Westech’s Steve Brule made a final, excellent point during testing. “There’s a reason that carburetor was at the swap meet. Probably because the last guy couldn’t make it work, so he’s passing his headache off on you!”
Edelbrock 750 - Performer
The Edelbrock 750 Performer has a reputation as a carburetor that works very well right out of the box. As we will see, our testing generally confirms that belief. It also offers some features that aren’t found even on more expensive versions. We really like the stacked boosters that offer excellent throttle response and the ability to easily change the primary metering rods just by loosening a single screw. To tune this carb, you will need to purchase a kit, but the price is reasonable. But there are limitations, too. The Edelbrock 750 will not work with most Holley-style drop-based air cleaners because of the fuel inlet position, but this can be remedied with a banjo fitting. Secondary metering access requires removing the entire lid, which isn’t difficult but is time consuming with 11 screws and connections. There’s also a remanufactured version of the Edelbrock 750 that we discovered after our testing that is also less expensive and virtually the same carburetor.
If this carburetor looks vaguely familiar—it should. Holley originally offered this street mixer with several features, including annular discharge boosters that offer excellent throttle response and are especially good on engines with long-duration camshafts. Plus, this carb has a no-fuel-spill design, where the lid gasket is above the fuel level. Summit purchased the tooling and now offers it at an attractive price equal to the Holley 3310C 750. The Summit carb uses some Holley tuning components like jets, power valve, and secondary vacuum diaphragm housing, which makes it simpler to find parts. The carb also comes with a cool tuning DVD. This carb was one of the few that performed especially well in part-throttle operation right out of the box.
Quick Fuel Slayer 750
When working with budget carbs, you rarely get innovation or upscale features. The features included with the Quick Fuel Slayer 750 make it that much more attractive because not only do you get an electric choke (the only others were the Q-jet and the Summit carb), but you also get screw-in idle and high-speed bleeds for tuning and a very simple, adjustable vacuum secondary (arrow). Wait, there’s more. The Quick Fuel Slayer also has a custom secondary metering plate employing Holley jets, making secondary jetting even easier and less expensive. Adding credibility, the Slayer won the out-of-the-box horsepower contest and was also the leanest at cruise rpm. We think at least one reason for this carb’s excellent performance is the drop-leg boosters that are normally found only on more expensive Holley-style carburetors. All told, we were very impressed with the Quick Fuel Slayer performance.