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I'm trying to figure out witch carb to put on my 383. The engine has a Voodoo #60103 hyd flat tappet cam kit 268/276;227/233;.489/.504 lift, speed Pro hyper 12cc dish pistons, cast iron vortec heads, and Hooker super competition sidemount headers. The trans. is a Th400. I would like to here opinions on vacuum secondary or mechanical? and cfm. any thoughts and opinions are appreciated.
Most will suggest a vacuum secondary carb with an auto tranny. I don't know if it's just me but I can never get my VS Holley's to run as well my Q-jets and if mileage is important, the Q-jet will win that battle by 10-15%.
Go to www.holley.com They have a calculator that you type your engine specs into and it comes up with a couple of different carburetors that are compatible to your set up.
I believe what you're saying, but I don't think your Qjet was set up properly, like the way Lars does them.
I had a great mechanic with almost 40 years of experience work on every q-jet I've had. None ever ran as good as my holleys. I'm sure a q-jet has its place on certain engines. I like the simplicity of the holley for ease of tuning it. Take off the fuel line and 4 bolts and you can change jetting, power valve, and accelerator pump. A holley doesn't need much choke for a cold start. On a q-jet, if it isn't set just right they don't want to run. If you have good luck with q-jets, keep using them, that's great. I just never had the total performance or consistency of a holley with a q-jet. I'm not trying to start an argument, I'm just sharing my experience.
I use a Holley 750CFM vaccum secondaries on my 383. Runs great, wasnt happy with the Qjet i had on it...it cut my horsepower by about 25%, again could have had it set up wrong.
I also use to have a holley 650cfm mechanical secondaries before the 750 vaccum and Qjet and i loved it, it had a deeper louder Meaner sound and i loved the feeling of those secondaries opening.