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Unread 01-27-2010, 01:33 PM   #16
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Join Date: Dec 2006
Location: Birmingham, Michigan
Posts: 2,652
Originally Posted by sonicr1 View Post
I was just thinking, it's only the 304, does it realy need to breath that much... maybe i'll compare... I was planning on selling one or the other to fund the build, but maybe I will hold off.
No, it doesn't. If you look up the cfm of the MC2100 that came on your motor, you'll be surprised at how low it is. Assuming it is the 1.14 venturi size, it'll be 300 cfm.

Number = CFM
.98 = 190
1.01 = 240
1.02 = 245
1.08 = 287
1.14 = 300
1.21 = 351
1.23 = 356
1.33 = 424

An aftermarket manifold won't increase the amount of air/fuel your motor can process. The charge that gets processed is dictated by the cylinder displacement and cam profile. If you aren't changing the motor internally at all, then throwing more air/fuel at it is worthless if it cannot process what you are giving it. A 600 is too much. You'll waste gas and it'll run like crap.

If you want a larger carb that will work well with your current configuration, improve off-road performance, and support potential future engine mods, I'd agree with the Holley 470 Truck Avenger for the 304, or the 670 for a larger motor.

Holley Performance Products 470 CFM Four Barrel Carburetor*0-90470

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Unread 01-27-2010, 04:24 PM   #17
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1975 CJ5 
Join Date: Aug 2009
Location: Washington
Posts: 39
Originally Posted by mowjoecj View Post
I kept my 2 barrel. the primarys are bigger than going to a small 4 barrel. to me the fuel milage is better, and i have a cam, headers etc. also a 304 is a small v8, so you don't really need a 4 barrel. however (I like talking out of both sides of my mouth) if the 2 barrel needs repair or doesn't run well and the 4 barrel is running great well there's your answer!
I just rebuilt my 2 barrel carb and it is still running rough and won't idle. It starts right up but runs rough and won't idle. I was thinking it might be the fuel filter or another vac leak. Any suggestions?
1975 CJ5 Levi Edition, 304 V8 AMC; Blue with denim seats.
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