I picked up this dual quad setup, offy high rise with AFBs. After running the numbers on the carbs through google, it looks like these are 600-625 CFM units from a 65 Mopar 413. I bought these for a street 350 sbc, comp 268h cam, 1.94 76cc heads. Pretty much a stock motor a little cammed up. The intake is really cool and I'd like to run it but I'm guessing 1200 cfm might be too much for a stock 350? What say ye? <a href="http://s4.photobucket.com/user/danhay/media/dual4s.jpg.html" target="_blank"></a>
I read that thread and I am wondering about the high rise nature of the manifold if it will have any effect on the CFM's. Also, if I understand correctly the AFB responds to engine vacuum but at what point is too much?
Use a progressive linkage on it and it will be fine,I'm running 1000 cfm on a mild 283,I run the edelbrock set up.
Depends on the intake, some are dual plane design while other are more open plenum. I run all my setups together one to one, I find that it gives the best plug reading (even distribution).
Even if you run them together they wont be too much if they are vacuum secondary carbs. If you hit the throttle hard and both primaries opened up it's still only 600cfm, and secondaries wont open until the engine vacuum calls for them.
Remember, that the 600 CFM rating is at a certain pressure drop across the carb (usually 1.5 in Hg). A dual 4 manifold will not be able to develop the same pressure drop as a single four manifold because of the larger port area, and as such neither carb will ever flow up to it's 600 CFM potential.
I would suggest smaller carbs (although the size you have can be made to work). The major issue you have is NOT the size however, rather you have Mopar carbs which you are going to place on a Chevrolet engine. For best results, you need to change (or modify): primary clusters, secondary clusters, main metering jets, step-up rods, and the auxiliary air valve. Personally, I would suggest finding a Mopar person to purchase the carbs from you, and replace them with: (1) a pair of Carter 9500s or 9510s (these have electric chokes) (one-to-one) (2) a Carter 4758s (manual choke) and a Carter 4761s (chokeless) (progressive) (3) a pair of either the 4758s or 4761s (one-to-one depending on whether you need chokes). All of the above (each are 500 CFM) were designed for use on small block Chevrolet, so dialing them in would be much easier and less expensive. Jon.
Thank you Jon, that's really the answer I was looking for , are these carbs worth messing with, or sell them to a mopar guy and get the right carbs. Since I haven't touched them, that's what I'll probably end up doing. Thank you for the part #'s so I know what I'm looking for!
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