Dual Quads (Holley) on a Small Block Questions

[Silverback51]

I run dual 660's on my 460 and love them.

While I'm pretty good with Holleys, I finally had to take the car to a shop with a dyno to get them dialed in. The 660 is a race only carb with mechanical secondaries, 4 jet center squirters, and no power valve in the front metering block.

It took him about 5 hours to get them to work right. We ended up swapping out the front metering blocks for ones with power valves. He drilled up a couple passages also. Since the secondaries use metering plates, not metering blocks you cannot use jets and the selection of sizes for the metering plates did not match what we wanted, we installed Quick Fuel jetted metering plates so you can use jets.

Personally I prefer mechanical secondaries. I want my right foot to control the opening of the secondaries, not a vacuum diaphram and spring.

[roadrod2000]

I have an original dual quad setup (from a 66 GT350 Shelby Mustang) on my HIPO 289. The engine is now in my Unique Cobra but is not yet finished. I ran the engine in a 65 mustang for many years and loved the performance from it. When I first got the setup it did not have the linkage, so I made my own and not knowing any better, connected both carbs to operate at the same time. The car always had a short lag in response (from too much fuel) and then came on like a rocket, when the vacuum secondaries opened it was like you mashed the throttle again. I originally thought that over 900 cfm was going to be way too much but other than the lag problem it worked fine. I now have the linkage set up right and am anxious to see how it runs now. My 289 had stock heads with 12-1 pistons, oversized valves and the Ford C7FE camshaft.