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How many of you have run a double pumper carb with an automatic trans. How was the driveability with this combo. I was always told that vacuum secondary carbs should be used with an auto trans. I have been talking to a good carb man and he is saying to run the double pumper with my combo. He says there should be no problem with mileage etc if I drive it sensibly and can control my right foot. He says that the vacuum secondaries don't kick in until about 4500 rpm. He is suggesting an adjustable float 4150 Holley.
 

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It all depends on your combo. I ran a dp carb but everything else was there supporting it.
A good converter, gears and an engine that could use it.
Can you run one on the "street" absolutely...but remember the curve tends to be richer and carb size is more critical.

That said, a vac carb is more forgiving and with the correct spring will perform good and "size" it self to the engines need.
 

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Double pumper or vacuum secondary makes no difference. What does make a difference is sizing the carburetor correctly. Everybody wants the ego trip of saying they have a 750 on their car over a 600 or 650. A vacuum secondary allows the use of the 750 but the car only uses the cfm it needs. A double pumper opens up all 4 butterflies and makes An automatic car seem lazy when in fact it’s too big. A manual can make up for this because you can slip the clutch and rpm it higher in lower gears. Be honest with your intentions and size the carb right and a double pumper will work just fine. A vacuum MAY get better mileage cruising if the secondaries don’t come in at cruise rpm but that’s a separate issue.
 

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Put a double pumper on it. As stated in other threads I've never seen a time when a vacuum carburetor out performed a double pumper. Buy a jet kit and learn to tune and you will never buy another vacuum unit. Let the spark plugs tell you which direction you need to go. You can tailor a vacuum carburetor to open when you want it to by the spring in the vacuum pod. We used to throw the check ball away in older models but I haven't worked on one in years.
 

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I did quite a few chassis dyno tests of various vacuum secondary carbs, and found that the secondaries almost never open fully, even at the redline rpm. I would demo this to the owner by sitting on the fender during the test, and reaching in and opening the secondaries manually at about 4500 rpm, always revealing a substantial increase in power.
 

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Put a double pumper on it. As stated in other threads I've never seen a time when a vacuum carburetor out performed a double pumper. Buy a jet kit and learn to tune and you will never buy another vacuum unit. Let the spark plugs tell you which direction you need to go. You can tailor a vacuum carburetor to open when you want it to by the spring in the vacuum pod. We used to throw the check ball away in older models but I haven't worked on one in years.
https://www.holley.com/products/fue...hCMpgxpDLS1mxHzsp83SyOEeEOo6ORwRoCZNUQAvD_BwE
 

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Put a double pumper on it. As stated in other threads I've never seen a time when a vacuum carburetor out performed a double pumper. Buy a jet kit and learn to tune and you will never buy another vacuum unit. Let the spark plugs tell you which direction you need to go. You can tailor a vacuum carburetor to open when you want it to by the spring in the vacuum pod. We used to throw the check ball away in older models but I haven't worked on one in years.
I always run a mechanical secondary for anything hi performance. Love the Quickfuel carbs, but the Proform is a twin to it and cheaper.

Liking the Brawler carbs and probably will pick this one up for a 400sbc I'm putting together with some good pieces for a 67-84 shortbed C10 if I sell my truck and find one.

https://www.ebay.com/itm/Brawler-BR...FM/382583364484?hash=item5913bedb84:rk:1:pf:0

I'm wanting this one though: https://www.ebay.com/itm/750-CFM-Br...epid=9025394075&hash=item1eedf3d7ba:rk:5:pf:0
 

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Technology is a wonderful thing and it is even affordable. If I were to run a vacuum carburetor I might try one but The double pumper will still out perform the vacuum. You can take a 750 vacuum carburetor and bolt it on just about any engine you want , you can tune until you are blue in the face and any average gear head can come behind you with a 750 DP and make it make more HP. The DP just has too many advantages including getting WOT easier and more consistent.
 
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