I have a 750 holley vacuum secondary in my streetstrip truck. If the vs carb is more reliable much better gas mileage more driveable around town it probably would be better for me.
Holley Carb Ported Vs Manifold Vacuum Advance Carb Basics
Double pumper vs vacuum secondary. I am not worried about gas mileage i want performance. Vacuum secondaries vs double pumper. Have a fairly stock 351c with holley 650 double pumper. Ps your friends 351c set with the 750 vac sec versus the double pumper why was he expecting a decrease in et in just going to a double pumper design carb. Tuned it with a narrow band o2 sensor. They are same and work the same and if you dont get the secondaries open will get the same mpg.
First there are no differences in the primary sides of a 750 vac secondary and a 750 double pumper holley. In my experience the double pumper can make for significantly more low speed torque at the expense of fuel economy. Or in actuality lack of vacuum. Would a 750 vacuum secondary be a little more friendly to her at idle and normal driving rpms. Leaned the carb up a bit. Now secondaries that use vacuum to open.
I was hoping not to sacrifice too much performance. I drive it maybe once a week around town but bring it. As long as you dont actuate the secondaries it uses no more fuel than a vacuum carb with the same size primary throttle bores booster type jetting and idle mixture. This is primarily a street car i know that the double pumpers are worth about 10 hp over the vacuum secondary but how is drivability. In summary mechanical secondary carbs are much more sensitive to engine size drivetrain gearing vehicle weight and rpm range compared with the controlled secondary configuration which is why. Relatively few vacuum secondary carb sizes can be made to work on a wide variety of.
Discussion starter 1 may 19 2009. Alot of times a vacuum secondary set up has a cleaner launch and they find their way on to a surprising number of bracket racing style set ups. Holley type vacuum secondary carbs are more forgiving compared with mechanically actuated double pumpers. Jump to latest follow 1 19 of 19 posts. My wife is very sensitive to fuelexhaust smells. Not on a dyno.
If there isnt much difference ill go with the dp for the power. S15v8 this sport takes 2 balls.
Gallery of Double Pumper Vs Vacuum Secondary
