holley carbs
Thread Starter
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Fleet Mechanic
Joined: May 2004
Posts: 1,436
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From: Montana
holley carbs
I was wondering can you make any 4150/4160 series carb a double pumper? For that matter what makes it double?, dual feed? Is that the perfered hp system? I mean you do want doublepump right?
Laughing Gas
Joined: Jul 1999
Posts: 1,048
Likes: 22
From: Lacey, WA
Egoman,
Hi, No I do not think you can easyly modify a non-double pump carb into a double pump unit.
What doublepump means is that the carb has 2 accelerator pumps. One for the front(primary) 2 barrels and one for the back(secondary) 2 barrels. The pumps are located on the bottom of the bowls.
Holley 4bbl carbs are either vacuum secondary or mechanical secondary. Mechanical secondary models are the "double pumpers".
Vacuum secondary carbs operate the secondary 2 barrels based on how hard the engine is "working" and the location of the gas pedal. This load is determined by a vacuum diaphram that meters the load. If you floor the gas pedal while in neutal the secondary 2 barrels will not open as there is no load on the engine and they are not needed.
On a mechanical secondary carb the back 2 barrels are directly controlled by the gas pedal linkage. Floor this puppy while in neutal and the back 2 barrels will open even though there is little load on the engine. This is where the second pump is needed. The reason there is a pump to begin with is to make up for the momentary lean condition as the throttle is being opened. The pump shoots fuel in as the pedal is mashed.
Vacuum secondary carbs don't need the second pump to make up for the momentary lean condition because the carb is "ready" for the secondarys to open based on load.
My advice would be to stay away from double pumpers for anything but an all out race engine. You will get better performance and fuel mileage out of a vacuum carb in a daily driver.
Hope this helps,
Lee
Hi, No I do not think you can easyly modify a non-double pump carb into a double pump unit.
What doublepump means is that the carb has 2 accelerator pumps. One for the front(primary) 2 barrels and one for the back(secondary) 2 barrels. The pumps are located on the bottom of the bowls.
Holley 4bbl carbs are either vacuum secondary or mechanical secondary. Mechanical secondary models are the "double pumpers".
Vacuum secondary carbs operate the secondary 2 barrels based on how hard the engine is "working" and the location of the gas pedal. This load is determined by a vacuum diaphram that meters the load. If you floor the gas pedal while in neutal the secondary 2 barrels will not open as there is no load on the engine and they are not needed.
On a mechanical secondary carb the back 2 barrels are directly controlled by the gas pedal linkage. Floor this puppy while in neutal and the back 2 barrels will open even though there is little load on the engine. This is where the second pump is needed. The reason there is a pump to begin with is to make up for the momentary lean condition as the throttle is being opened. The pump shoots fuel in as the pedal is mashed.
Vacuum secondary carbs don't need the second pump to make up for the momentary lean condition because the carb is "ready" for the secondarys to open based on load.
My advice would be to stay away from double pumpers for anything but an all out race engine. You will get better performance and fuel mileage out of a vacuum carb in a daily driver.
Hope this helps,
Lee
Thread Starter
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Fleet Mechanic
Joined: May 2004
Posts: 1,436
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From: Montana
Cool thats what i was thinking, My engine is going to be highly modified its not a drag racer but it should be just a street/strip application so i want as powerful a carb as i can get while still maintaining street-ability.
Moderator
Joined: Dec 2001
Posts: 22,436
Likes: 17
From: Louisville,Ky.
Depending on what cubic inch it is, I would use either a 600cfm or a 750cfm.
Personally, I like the Edelbrock carbs for street driving. They have mechanical secondaries, but use and internal flap to control airflow on the secondaries based on airflow needed.
Personally, I like the Edelbrock carbs for street driving. They have mechanical secondaries, but use and internal flap to control airflow on the secondaries based on airflow needed.
Thread Starter
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Fleet Mechanic
Joined: May 2004
Posts: 1,436
Likes: 0
From: Montana
Well i hope to make it a 416 FE stroker with a 584/607 crane cam....I want a single plane intake but I might just get a dual just need to top it of with the perfect carb....gotta go with a holley though.
