Double Pumper Benifit?

[Clutch123]

What would be the benifit of having a double pumper on my holley 650? bolted on to a modified 318ci?

Will i just drown it or will it acually run better?

Thanks alot!


Cheers
Ray :wasted:

[71fish]

IMO.. certainly no kind of expert, but I would only use a double pumper if you are running a big cam. Vaccuum secondaries are best on a car producing lots of vacuum.. prob better tunability and throttle response. You can always jet down the double pumper, but I'd put V/S carb on the 318.

71fish

[OUTLAW]

It depends on what you wan tot do with the car. Dbl pumpers are more race orientated than a vac secondary carb. Drivability is really hampered with a dbl pumper. On  a mild motor I recommend a vac secondary carb, I ran a dbl pumper on the street for a long time and when Iswitched to a vac secondary carb, no noticeable loss of power but the car became fun to drive again. At low rpm dbl pumpers seem to flood/starve and jerk around, at high rpm its a whole different story. So figure it from there , what do you plan to do with the car will be the deciding factor

[miketyler]

this is a great thread so far. My car is going to be a driver and will not be raced. It came with a double pumper Holley Avenger but it was "muddy" on take off. I am thinking I need a vacuum secondary carb. Whats a great vac secondary carb to go with? Something like the Edelbrock line or ?   

[MEK-Dangerfield]

OK, I'll step my foot into this muck.    I have a double pumper on my 440 with auto trans. The people "in the know", say the double pumper is more for manual shift cars, and racers. The trouble is, I have a big cam. I never could get a Holley street avenger to work right for me. There was always a bog when I would punch it. I'm guessing the lack of vacuum was my trouble, so I went back to the double pumper. Hey, I know it won't exactly help gas mileage, but MAN does my car move with it.  :thumbs: I guess what I'm saying is... your set-up, and intentions come into play here.

   Mike

[Chryco Psycho]

the double pumpers are far more crisp responding than a Vacuum secondary carb the big problem is expecting a a double pumper to not bog when floored from idle which is often impossible , you need to learn to drive them & often snap them 1/2 open & wait a second to get some RPM built up before slamming them wide open , it take practice to get 100% from a double pumper

[matt63]

Some or perhaps all double pumpers linkages can be adjusted to open the secondaries a little later in the progression.  This could help driveability and gas mileage.   Also, with vacuum secondarie carbs changing the spring can allow the secondaries to open sooner/later.  On my Demon 750 a lighter spring made a big difference in the engine responsiveness off of the line.

[Ravage]

I just tossed a street avenger on my car an hour ago and it runs great.318 with a lumpy cam.Had an edlbrock on there that would bog on hard turns ,but the holley is treating me good. It came with extra spings so you can make adjustments to it.Though it sits higher and I put a dimple in my hood when I closed it  so I took the air cleaner off for now.(also have an RPM performer intake that sets everything up too though)