Gee, all of your examples are light high HP rigs. Holley tells you they belong on race motors or light street cars. Why, because when you stomp the throttle the secondaries open even at low rpm (its called over carburation) and if the engine can't rev (either break the tires loose or accelerate fast), the engine does and will stumble causing poor performance. A heavy truck and a D/P are a poor combo at best and a disaster at the worse, besides the poor fuel economy. An old saying from the 60s; "Just because it works for "Grumpy" Jenkins doesn't mean it will work on your street car."
wrong,
the 460 is in a lifted xcab 150, with 1 ton axles (about 7000 lbs)
a heavy truck or car can be easily fixed with gearing
now back to the original post in were i said a dp is not suitable for a stock motor
maybe you should fully read the post before speakin!!!!!!!!!!!
wrong,
the 460 is in a lifted xcab 150, with 1 ton axles (about 7000 lbs)
a heavy truck or car can be easily fixed with gearing
now back to the original post in were i said a dp is not suitable for a stock motor
maybe you should fully read the post before speakin!!!!!!!!!!!
I have no problem with you wasting your money on wrong equipment and setups, I have a problem with guys like you telling others to waste their money. Oh yeah, No gearing can't fix somethings.
Tell you what, if you are set on running the DP go ahead and do it, and if after some tuning tweaking and general screwing with the carb, you have a slight bog or stumble that just wont go away, its the second accelerator pump over fueling the engine at lower rpm than it was designed to be used for, and the DP is a performance carb, and as such it will not get the fuel mileage that a vacuum secondary carb will give you, but thats in the Holley line, others use metering rods and such to allow the engine to attain higher rpms before dumping a bunch of gas into the engine. In my opinion a 600 will be a bit more responsive but a 460 will take all the gas you want to put thru them and a 750 will work just fine on a 460. If you go to Holley's website they have a cfm calculator to help you figure it out better if you really want to know what you need and what may never really get used as far as cfm goes.
with the research ive done several 385 guys have used a 850 doublepumper for even a mild build say headers ,intake .i read a old article in super ford that tested different carbs and the 850 dp gave best results this guy even said the vacum sec carbs had a slight hesitation ,another guy said he had built a 77 460 stock bottom end with 7.7.1 compression,a home port,polish job on the stock heads ,rv cam ,headers and 850 holley and made 370 horsepower
Tell you what, if you are set on running the DP go ahead and do it, and if after some tuning tweaking and general screwing with the carb, you have a slight bog or stumble that just wont go away, its the second accelerator pump over fueling the engine at lower rpm than it was designed to be used for, and the DP is a performance carb, and as such it will not get the fuel mileage that a vacuum secondary carb will give you, but thats in the Holley line, others use metering rods and such to allow the engine to attain higher rpms before dumping a bunch of gas into the engine. In my opinion a 600 will be a bit more responsive but a 460 will take all the gas you want to put thru them and a 750 will work just fine on a 460. If you go to Holley's website they have a cfm calculator to help you figure it out better if you really want to know what you need and what may never really get used as far as cfm goes.
Usually not true. It's the secondaries opening and causing air flow thru the carb to drop so low it won't move any fuel that cause the bog or stumble. AKA as to much carb or the wrong carb.
with the research ive done several 385 guys have used a 850 doublepumper for even a mild build say headers ,intake .i read a old article in super ford that tested different carbs and the 850 dp gave best results this guy even said the vacum sec carbs had a slight hesitation ,another guy said he had built a 77 460 stock bottom end with 7.7.1 compression,a home port,polish job on the stock heads ,rv cam ,headers and 850 holley and made 370 horsepower
Unless they show you timing slips, they are then using seat of the pants as a guage and that is never accurate. Too many miss the stumble and when the motor does go think it is stronger. Timing slips will prove them wrong. As to the guy with the 7.7 compression, Was the a dyno sheet? If not I call BS. Even the 10.5 to 460s only had 375 horsepower.
boy o boy carby/s, generally a vac,secondary is more street friendly for almost all people
except those who like d/pumpers. cfm for a 460 depending on state of build 600/850 .
anyway i like predators"
yes the guy with the 7.71 compression 460 did have dyno sheets and quarter of a mile time slips ,he had no reason to lie is was all in super ford ,the guys from super ford had a reply to this guy and with their own dynoed 460 had almost the same results .im not defending anyone but i do know it doesnt take alot to make power from a 460 ,ive ran dps and vac sec carbs i like em both
I would agree with Bear. On a stock 460 a 750 dp is over carberation. Reading what's out there, a 750 is overcarb for the stock 460. I have one on a 545 stroked 460 that produces 500 hp and it's in a 78 F350. If I punch it, it smokes the rear tire (open differential at this time). It works for me because of the engine build.
Holley says that vacuum secondaries work best for heavier vehicles because they respond to engine load, not the demands of your right foot. Bear is spot on. Mechanically opening secondaries on an engine with insufficient signal to draw and utilize the carb capacity can only lead to poor performance.
For those that think the legendary Carter carb is all mechanical -just look down the air horn. It has a weighted air valve that functions on the same principle as Holley's vacuum secondaries.
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