Carbs HELP

[240ZR]

Part # 1282010C ZZ4

650 Demon - Vortec ZZ4

Mechanical Secondaries

 

Part # 1282010VC ZZ4

650 Demon - ZZ4

Vacuum Secondaries

 

 

Whats the Differance Between a Mechanical and Vacuum????? what do i want for my hybrid Z?

[280Zone]

The mechanical vacuum difference is how the secondaries are actuated. Mechanical = faster more consistent activation but you end up with your foot in it more often so worse gas mileage.

 

For most perfornance applications I would suggest mechanical.

[Pop N Wood]

Go to Holley's web site and look up their recomendations. Vacuum secondaries means the secondarys are opened by engine vacuum, meaning the second set of butterflys only open if the engine needs the air. Mechanical secondaries are opened with the throttle linkage.

 

Holley doesn't recommend a mechanical secondary unless the car weighs less than 3200 pounds and the rear gears are 3.7 or lower. Basically a car that is going to accelerate quickly. Our Z's fall in that catagory.

 

But supposedly mechanical secondaries are more work to tune and like said above can get worse gas mileage. So that is something else to keep in mind.

[veritech-z]

Just to clarify the way the differences work: The mechanical secondaries are opened with a small addition to the throttle linkage that engages them at a given pedal angle, whereas the vacuum secondaries are opened via a vacuum signal, kind of like how your vacuum advance distributor would work. So what 280zone said is totally right, the mechanical would be better for performance/spirited driving and the vacuum should give you better fuel economy for driving around town.

 

edit-Pop you beat me to it! that popped up right when I posted...