Double Pumper Vs. Vacuum Secondary

[LuckyWinner]

Which is best for our light weight roadsters with big power? Looking at street use not track.

[carbon fiber]

the double pumper will make a little more power if that's what you want. if it's a driver, not a race car, i'd go with the vacuum secondary. they're easier to tune and better mileage/driveability. you can get a kit with different springs to tune the secondaries. just make sure to get the right cfm carb for your application, whichever you choose.

[Avalanche325]

Double pumper. These cars are too light for vacuum secundaries.

Vacuum secondaries work off of engine load. That works much better when your engine is pulling a heavy car.

I called QuickFuel about a week ago, they said DP.

[edwardb]

This topic is discussed a lot over on the other forum. While some guys are able to get the vacuum secondary setup to work OK in these cars, the overwhelming choice is a double pumper. It's not only a power discussion, it's about throttle response, driveability, etc. As already pointed out, light cars and manual transmissions = DP. Not vacuum secondary. My own personal experience bears this out. Installed a Holley Street Avenger vacuum secondary in my Mk3 during the build. Was never able to get it tuned to where it started and ran crisply, launched without hesitation, etc. Gave up and installed a Quick Fuel double pumper. Was the cheapest engine overhaul I've ever done because the car was like it had a different motor. It does everything better, and is actually much easier to drive.

[riptide motorsport]

DP..

[al1957]

Definately a DP, the vacuum secondaries can hit hard and uncontrolled wheel spin will follow. Happened to me once, the DP is easier to control the power.

[Gumball]

DP - for the stated reasons above, primarily the fact that the mechanical linkage allows for much more linear use of the secondaries in these light cars. I have a 650 cfm Holley on my 347 and with just a little fine-tuning, it starts and runs great; idles nicely at 700 rpm and pulls smoothly off the line with no flat spots.

[cob427sc]

I have 2 Edelbrock 4 barrels on an edelbrock manifold. Progressive linkage between the primaries and vacuum secondaries on both carbs. Runs perfect after a little tuning for an overly rich idle. I guess having the 2 primaries on mechanical linkage gives me almost the same effect as a DP.

[carbon fiber]

i've never ran vacuum secondaries in anything that weighed less than 2800lbs. (600 lbs. heavier than the roadster, i know) i used 750cfm holley with quickchange secondary kit. i changed three springs before finding the right one, but never had a problem after that.

[willy]

I like the DP