Swap Out Thermoquad

Tech Question


Nawaf Al Balushi, east riffa, bahrain, 1974 dodge challenger 440 c.i

Dr. Rick, Help me out please! Im driving my 1974 DodgeChallenger with 1978 440 c.i engine under the hood, the engine has a CarterThermoQuad carb, recently the carb starts farting and hard to start-upsometimes, so I decided to replace it with a new carb. Now considering thatmy engine runs with an orange E.C.U., my question is: What is the streetuse cfm you’d recommend? And there is any issue for single or double pumpfor the street application? The mechanic guy told me that I can’t run a750cfm carb because it will be very rich with fuel and need some electricupgrades. Is that true doc? A little help will be appreciated Yourssincerely,



The stock ThermoQuad was 850 CFM. If you feel you must replace it, I’d useeither a Holley vacuum secondary spread-bore, or an Edelbrock AVS. Anythingin the 750-850 CFM range is fine, as long as the carb has a “demand” typesecondary arrangement.

Actually, if you run a carb that’s way too big, the engine can be lean, butnever rich. Your mechanic’s statement shows a basic lack of understanding ofcarburetor operation.

My recommendation: The T-Q is VERY easy to rebuild, and kits are widelyavailable. Or buy a rebuilt, or have yours rebuilt, by “Demon Sizzler” seethermoquads.com . The T-Q is the best hot-weather carb ever built, by far!


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