eledbrock 750 vs holley 750
11-27-2008, 12:26 PM
#4
4th Gear Member
Join Date: Oct 2007
Location: Houston, TX
Posts: 1,049
11-27-2008, 01:01 PM
#6
6th Gear Member
Join Date: Apr 2007
Location: California
Posts: 10,468
Why run a vacuum secondary carb and then just tune it so the secondaries don't open? You should run the right carb in the first place and then you won't have the throttle blades on the secondaries only part way open and disrupting air flow and causing fuel atomization to be disrupted.
Keep in mind that the NASCAR Busch engines are 358 cubic inches and making 500-550hp at 6,500rpm....with a 390cfm 4bbl. The carb's job isn't to let as much air into the engine as it can, it's to meter fuel PROPERLY. It needs velocity to do that, and velocity is generated by creating a restriction that forces the airflow to speed up. There's a balance between restriction and velocity. Too small and the engine is strangled, too large and the fuel isn't metered effectively. Generally speaking you gain more power from having a bit more velocity than you do from having a bit less restriction. It's even more important on a street car that spends 99% of it's time at low rpm and part throttle, where airflow is minimal.
Keep in mind that the NASCAR Busch engines are 358 cubic inches and making 500-550hp at 6,500rpm....with a 390cfm 4bbl. The carb's job isn't to let as much air into the engine as it can, it's to meter fuel PROPERLY. It needs velocity to do that, and velocity is generated by creating a restriction that forces the airflow to speed up. There's a balance between restriction and velocity. Too small and the engine is strangled, too large and the fuel isn't metered effectively. Generally speaking you gain more power from having a bit more velocity than you do from having a bit less restriction. It's even more important on a street car that spends 99% of it's time at low rpm and part throttle, where airflow is minimal.
11-27-2008, 01:47 PM
#7
5th Gear Member
Join Date: Nov 2008
Location: SC
Posts: 2,401
The big advantage to a smaller vav secondary carb is the only time the rear throttle blades open is when they are needed. Both carbs come with a tuning manual and DVD to guide you step by step. If you give me some more information on your engine an the car that it's in I work you up a carb in each brand and you can make up your mind which one you like better.
Anyone who tells you you can pick up 30hp by moving into a Holley never saw a properly tuned edelbrock. I like both carbs. I've used both in differant set ups and both will get the job done.
On most pretty aggressive 302's a 650 os more than enough carb. If you are not running a bunch of stall or a tall gear and primary driven on the street a Vac seconday carb will perform better and be a lot more fun on the street and deliver way better mpg. In most cases throttle responce will be better for street use as well.
11-27-2008, 02:47 PM
#8
4th Gear Member
Join Date: Oct 2007
Location: Houston, TX
Posts: 1,049
Why run a vacuum secondary carb and then just tune it so the secondaries don't open? You should run the right carb in the first place and then you won't have the throttle blades on the secondaries only part way open and disrupting air flow and causing fuel atomization to be disrupted.
11-27-2008, 03:48 PM
#10
Thread Starter
Join Date: Nov 2008
Location: ky
Posts: 18
What has been failed to tell you is both carbs have their places and more depends on your engine than the brand of Carb you use. If You have a mildly built 302 (-+300hp) a 600CFM edelbrock carb (1406)or a Holley 570 Vac sec street avenger (8570) will work about the same. Both are easy to tune and both offer about the same performance. In most cases a small Vac secondary carb is all you need until you get up in some real power.
The big advantage to a smaller vav secondary carb is the only time the rear throttle blades open is when they are needed. Both carbs come with a tuning manual and DVD to guide you step by step. If you give me some more information on your engine an the car that it's in I work you up a carb in each brand and you can make up your mind which one you like better.
Anyone who tells you you can pick up 30hp by moving into a Holley never saw a properly tuned edelbrock. I like both carbs. I've used both in differant set ups and both will get the job done.
On most pretty aggressive 302's a 650 os more than enough carb. If you are not running a bunch of stall or a tall gear and primary driven on the street a Vac seconday carb will perform better and be a lot more fun on the street and deliver way better mpg. In most cases throttle responce will be better for street use as well.
The big advantage to a smaller vav secondary carb is the only time the rear throttle blades open is when they are needed. Both carbs come with a tuning manual and DVD to guide you step by step. If you give me some more information on your engine an the car that it's in I work you up a carb in each brand and you can make up your mind which one you like better.
Anyone who tells you you can pick up 30hp by moving into a Holley never saw a properly tuned edelbrock. I like both carbs. I've used both in differant set ups and both will get the job done.
On most pretty aggressive 302's a 650 os more than enough carb. If you are not running a bunch of stall or a tall gear and primary driven on the street a Vac seconday carb will perform better and be a lot more fun on the street and deliver way better mpg. In most cases throttle responce will be better for street use as well.