Modified Mustangs & FordsHow To Engine
Dual Quads - Twin Win, Or Double Trouble? Part 2
The merits of dual quads on a small-block Ford
When discussing multiple carbs for Fords, one can't ignore the six-barrel setups, which were optional on assembly line 390s and 406s in the early '60s. Ford offered a similar over-the-counter arrangement for small-blocks, which Carls has reproduced as well. We didn't test any triple-twos, but believe them to be strong performers. That said, Ford had embraced dual quads by the time it developed really impressive cylinder heads, so the factory six-barrel pieces are of a moderate performance, low-rise design. Both carb configurations use a progressive linkage, meaning you're cruising on just two-barrels until you roll hard into the throttle.
For what it's worth, the 1966 Ford High Performance parts catalog advertised a 12-15 horsepower improvement for the small-block, triple two-barrel Holleys (C4DZ-6B068-B), 25-30hp for a dual-quad Carter kit (C40Z-6B068-E), and 30-35hp for the first dual-quad Holley setup (C6ZZ-6B068-A)--all compared to a production iron four-barrel intake and Autolite carb. When the Trans-Am induction appeared in 1968 catalogs, it was advertised to be worth 45-55 horses "depending on the camshaft your engine utilizes."
Lest we leave a blanket impression that dual quads are better than triple-two-barrels, Mopar undoubtedly knew what they were doing when they simultaneously rode the fence with dual-quad Hemis and Six Pack 340s and 440s at the peak of the muscle era. Its six-barrel manifolds were decidedly high-performance in design, and by all accounts, the results were impressive. Fortunately, today's Ford picks involve some intriguing items never offered back in the day--for example, the Dove FE Tunnel Wedge triple-two intake, a hardcore performance piece which would be absolutely wicked on an early '60s big-block Galaxie!
Randy Dunphy's 331 was in transition during our testing, morphing from a '90s underhood look to something right out of the Total Performance era. Of course, the two-fours are a big part of the transformation, but so are the Holman Moody valve covers, which Dunphy installed during our test. Available brand-new at www.holmanmoody.com, these covers are a great alternative to some of the more commonly seen vintage-themes. We can't promise clearance on every combination, but can say that the HM units easily cleared the FRPP bolt down roller rockers on this engine, and they come in two versions--street oriented covers seen here ($260), and a competition version with twin comp style breathers ($355).
Duals for All
We're pleased to report that almost every '60s-era Ford engine can be fitted with factory-style dual quads, using readily available brand-new components. While FEs were the only '60s Ford engine to get multiple carbs on the assembly line, FEs and small block multi-carb setups were heavily promoted by Ford through its parts department. The 351W and 429/460 arrived too late on the scene to get similar billing, thus it's interesting that applications for these engines are available today as well. Price Motorsport makes the 351W piece you see here (on right), while Blue Thunder makes the 429/460 application (on left)--both of which are available through Carl's.