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On a typical 4 barrel carb with vacuum secondaries the accelerator pump discharges into the primary venturies. Carbs with mechanically actuated secondaries are usually referred to as a "double pumper". A double pumper will have 2 accelerator pumps. One discharging into the primaries, the other into the secondaries. The accelerator pumps provide extra fuel so the air fuel ratio doesn't lean out when the throttle is quickly opened...
 

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Depends, there's "square bore" carbs that have the same size primary and secondary throttle bores and "spread bore" carbs with small primaries and huge secondaries. My guess is the Ford has a square bore intake so the 850 would need to be a square bore carb. IMHO an 850 is kind of big for a 351/400...
 

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Junkyard Kustoms
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Discussion Starter #6
lol

i was thinkin 1.150 dominator marine carb with a torker cam kit from edelbrock......haha i can get the manifold for 150$ so i was lookin at the 800dp for 350$
 

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Double pumpers are not the best bet for a street engine....They work best at wide open throttle. If you want a decent street Holley, get a 780/vacuum secondaries...you will be much happier with it.
 

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Double pumpers are not the best bet for a street engine....
It depends on the combo. I'm running a heavily reworked 750 dp on my 440, with an automatic trans no less. Of course the 10" converter and 4.10 gears help a bunch. With a stock converter and highway gears, vacuum secondaries would be a better choice...
 

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Tazz
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The 600 Edelbrock works just fine on a mild to hot SBC 350 though. To much carb will give you a lot of headaches and kill your bottom end..washes it clean!!! Then the brngs galled and it's time for a rebuild..tadaaa!!! You are talking street car..arn't you??? Drag cars is a WHOLE different story guys!!! Ya know..make a pass..rebuild the engine...make a pass!!!


Tazz


Rat Rods Rule!
 

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I had a '40 Chevy Panel truck with a 454. Had an 850 Holley with double pumper and mechanical secondaries. Wasn't a daily driver but it went to several NSRA Nationals around the country and local rod runs pullin' a camper no less, It ran great and had big torque on the bottom end. Big block may be a little more able to handle it than a SB tho.
 

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