Hey everyone I was wondering what size carb I need to use for the old draft through turbo setups off the t types? I'm putting this set up on my monte carlo.
what carb?
- Thread starter WannaBeGTP
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Well, if it is the setup I am thinking of, it is a setup without a pressurized carb. If it were pressurized, you can usually use a much smaller carb than a draw through system because the pressure seen at the carb is not atmospheric, but atmospheric plus boost, and a carburetor works off of a pressure differential in the venturi. In a blow through ( pressurized carb) system, you would also need to have a rising rate fuel pressure regulator so that the fuel pump can overcome the pressure at the needle and seat and not have the fuel pushed back to the tank. At sea level, for example, the pressure a carb is really seeing is 14.7psi + boost ( for 5 psi it would be 19.7 psi, etc). So, boost is really just the pressure differential between atmospheric pressure which varies with altitude due to the size of the column of air above you. Well, now that I am done showing off, I would just run a 600cfm Quadrajet as that is what GM put there to begin with. A 600 cfm Quadrajet is identical to a 750 or 800 cfm Quadrajet except that it has a small stop on the secondary air valve which prevents full opening. Pretty much any Quadrajet built after 1976 should be a 600. Use one off a 305 or 350 however ( depending on which engine you have) because the idle feed restriction will be properly sized for your engine.
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