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Old 06-28-2002, 11:26 AM
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Post carb

is edelbrock 600 carb sufficient for sb 400?

also, what's a good temp. to keep the 400 running?

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Old 06-28-2002, 01:08 PM
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It would probably be okay but a double pumper would be better or a 750 just my opinion(wrenchturner)
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Depends on what the engine is for. If you are going to run mainly on the street and occasional strip use, the 600 w/ vacuum secondaries is perfect. Anything bigger is for all out racing engine. Double pumper is definitely a race only option. Always resist going too big on a carb. Also, for the street, get a 108deg intake manifold (dividing wall between sides of carb). Edelbrock Performer or even a Performer Plus is great. Other manufacturers have equivalent designs. Avoid the Victor and other 360deg designs (no divider) 'cause you will suffer on the botom & mid range where you will be burning all your 92 octane!
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Old 06-28-2002, 05:50 PM
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Double pumper a race only thing? excuuuse me? The ONLY carb for a 350-400 ci motor is a 750 double pumper.. they are fine on the street...
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Old 06-28-2002, 06:49 PM
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I think we should clear up any misconceptions regarding cfm ratings and engine needs in this post. One of the questions I hear often is what is the best for performance, double pumper or vacuum secondary. Almost without exception this can be answered by saying double pumper, in almost every situation the extra fuel delivered by a double pumper will assist the engine during torque demand by keeping the A/F mixture at 11:1 or richer for longer periods than a vacuum secondary carb could. Of course a vacuum secondary carb will not need the extra fuel due to the restricted airflow from the closed rear secondaries.

Do you need the extra airflow afforded by a double pumper carb? The answer is yes if you are looking for the ultimate in performance and torque production, a double pumper carb will always outperform a vacuum secondary carb on the dyno during sudden throttle angle changes. The problem is that it is possible to stall an engine with to much air and fuel at once and backfire through the carb, this is the principle reason why it is always recommended to run a vacuum secondary carb on the street. My question to you is are you smart enough to keep some restraint and not floor the accelerator when the engine is under heavy load at low rpm so you will not stall the engine? If the answer is yes than you are ready. This is why manual transmission cars usually have double pumper carbs from the factory and automatics usually came with vacuum secondary carbs. The manual trans operator has more control over engine rpm than an automatic driver has.

To the average idiot consumer this is a wise thing to do, but the average hot rodder is smart enough to know better. As for cfm ratings you can run as big as you want but at some point the restriction reduction caused by going bigger will not offer any performance increase and it will be a waste. You could conceivably run a 1150 cfm carb on a 305 as long as you could stand having to be careful with how much throttle you give it under load and low rpm. I have run 850 DP Holley carbs on 302 Fords with no problems and only had to be careful how I drove it, a full throttle stomp at a green light will leave you standing there looking like an idiot.

If I had a choice on carbs to run on the street I would have to say a 750cfm Holley double pumper is all the carb you will ever need unless you have one very radical big block, and then I would recommend an 850 DP for up to 600 HP. A Dominator looks nice and can be driven properly as long as the operator is aware of the limitations. On the other side of the coin a 600 vacuum secondary will offer you 90% of the performance without exacting the toll of watching how you play with the throttle. Ultimately it is up to you, if you don't mind learning to drive a car with a careful right foot then a double pumper is right for you. If you just want to stomp and steer it, then a vacuum secondary carb is for you.

The trade off is to get the extra 10% of torque from the engine you need to make a driveability sacrifice with a DP carb and learn to drive it. Is it worth it? that's up to you.
“She may not look like much, but she's got it where it counts, kid. I've made a lot of special modifications myself.”

— Han Solo
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Old 06-28-2002, 06:59 PM
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carb size is a relative thing,compression being the biggest, an 8.5 engine needs more carb than a 10.0 engine.the rule is use the smallest carb needed to run the engine at the max rpm it will be run 1979 NASCAR came down with a 390 carb rule meaning the only carb that could be run was a 390cfm holley,we all thought that was the end of the big blocks, the next year the big blocks were back faster than ever, these modifieds now were running between 13 to 14:1 in compression and still turning 8000 rpms So I would say the 600 edelbrock would power the 400 if the compression is moderate(9.5)
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