What size carburetor do I need for a 454?
| Carb Size | Manifold Vac | Horsepower |
| Holley 650 | 1.8 | 470.4 |
| Holley 750 | 1.5 | 477.15 |
| Holley 850 | 0.5 | 474.3 |
| Holley 950 | 0.4 | 471.5 |
What is the most factory hp on 454 engines?
Surprisingly, the 454 laid down an impressive 330 horsepower and 475 pound-feet of torque. Naturally, the truck-based 454s were tuned for torque, so having nearly 500 pound-feet wasn’t a big...
What is 30 divided by 454?
The basic rule for divisibility by 4 is that if the number formed by the last two digits in a number is divisible by 4, the original number is divisible by 4; this is because 100 is divisible by 4 and so adding hundreds, thousands, etc. is simply adding another number that is divisible by 4.
What size carburetor do I Need?
It’s common to see efficiency values of 70-80% up to 95-110% for race engines. For example, let’s find the recommended carburetor size for an engine with a displacement of 302 cubic inches, a max speed of 7,500 RPM, and 80% volumetric efficiency. carburetor size = 302 × 7,500 × .8 ÷ 3456 carburetor size = 524.31 CFM
What is the horsepower on a 454?
The GM marine 454 had a bore of 4.25 inches and stroke of 4 inches with compression ratio of 8.1-to-1. The engine breathed through a four-barrel carburetor, and ignition was provided by a Delco Electric unit. The marine 454 weighs 980 lbs and makes 330 horsepower, at its maximum RPM of 4,400.
What CFM does a 454 need?
Air flow required is c.i.d. x rpm / 3456. Or 454 x 5000 rpm = 2270000/3456 = 656.83. So at 5000 rpm, your 454 only needs 656 cfm at 100% volumetric efficiency.Mar 28, 2006
How much horsepower will a 750 cfm carb support?
As an example, a 750-cfm carb on one of my street/strip Chevy 383 small-blocks can make more than 600 streetable hp, whereas an engine less well spec'd may only make 540 to 550.
How much horsepower will a 650 cfm carb support?
Consider using your Google-Fu to find out how much power a 650 cfm carb can produce. If possible, you can expect to get answers of 450-470 HP, but it's not the right fit. Even if horsepower were king, there wouldn't even be any issues with torque in any vehicle.Feb 18, 2022
How do I know what size carburetor I need?
The formula for calculating how much CFM (cubic feet per minute) your engine requires is: CFM = Cubic Inches x RPM x Volumetric Efficiency ÷ 3456. Any ordinary stock engine will have a volumetric efficiency of about 80%.Apr 2, 2019
Is 600 cfm carb big enough?
A 600-cfm carburetor may perform quite well on a stock 350 Chevy. However, the minute you start weaving in power adders like a hotter cam, a dual-plane performance intake manifold, and aluminum heads you're going to need 700-750 cfm.Feb 27, 2017
Can a carburetor be too big?
According to all of the carb charts you are too big for a street engine. The race 289 used a 715 cfm Holley. You would need a lot of rpms to really need a 750. Throttle response and smoothness of acceleration are some of the problems with too big a carb.Dec 17, 2005
How much horsepower will a 4 barrel carb add?
With so much fuss about EFI, you'd think we'd given up on the good ol' four-barrel carburetor completely. It's hard to beat the tried-and-true four-barrel swap. For less than $400 and a day, you can easily bolt 25 hp onto your car's engine.Dec 1, 1998
Why use a double pumper carb?
The reason double pumpers (mechanical secondary carburetors is their proper name) have these twin accelerator pumps is to prevent a momentary lean situation during quick throttle blade movement. All carburetors use an accelerator pump circuit, however many only have one on the primary barrels.Nov 24, 2020
Do carb spacers add horsepower?
On the 350, best results were found with a 2-inch spacer. Its use produced up to 6 more horsepower at peak and as much as 14 more at 750 rpm over peak power. On the 400-inch engine, a stack of three 1-inch spacers produced the best results.Jan 1, 2006
How do I know if my carburetor is too small?
If the carburetor is too small, it restricts airflow into the engine. The cylinder can't fill up all the way. This starves the engine and results in slow acceleration and a lack of top-end power. A larger displacement engine running at higher rpm will require more air and fuel.Apr 13, 2017
Which is better Edelbrock or Holley?
As I mentioned before, right out of the box an Edelbrock will be better. However, if you're a DIY guy who likes modding things around – Holley will be your best pal. The tuning is more responsive and less touchy than not only Edelbrock, but most other manufacturer's carbs.
Is a 600 cfm carb too big for a 305?
500 or 600 is fine for a 305.Sep 23, 2010
What is a secondary carburetor?
A vacuum secondary carburetor is usually most fuel efficient when its used on street driven cars that have automatic transmissions. Vacuum secondary carburetors have one accelerator pump and work off sensing the engine load, which progressively open the secondary butterflies as rpm increases. A mechanical secondary carb uses mechanical linkage to open the secondary butterflies and most also have dual accelerator pumps (a.k.a. double pumper). Mechanical secondary carbs are best used on applications with more radical camshafts, high rpm racing situations, and manual transmissions.
What is a mechanical secondary carb?
A mechanical secondary carb uses mechanical linkage to open the secondary butterflies and most also have dual accelerator pumps (a.k.a. double pumper). Mechanical secondary carbs are best used on applications with more radical camshafts, high rpm racing situations, and manual transmissions.
What is the volumetric efficiency of a stock engine?
Any ordinary stock engine will have a volumetric efficiency of about 80%. Most rebuilt street engines with average bolt-ons have a volumetric efficiency of about 85%, while race engines can range from 95% up to 110%. Example: Using a 355 CID engine x 5,500 max rpm = 1,952,500.
Can too much carburetor choke an engine?
Unfortunately too much carb is a common mistake made that can actually choke the overall performance of your engine. The right idea would be to proportion the carburetor to the engine's volumetric potential (breathing ability).
What is a 950 CFM carb?
Think of it this way: A 950 cfm carb has a larger area to flow though compared to a 650 cfm carb. So, if you are running a 950 when you really only needed a 650, then you are moving your 650 cfm of air through a 950 cfm opening.
How much vacuum does a Holley carb have?
Of course, there are other factors such as vacuum under the carb. As we recall, Holley rates their four-barrel carbs at 1.5 inches of vacuum and their two-barrels at 4 inches of vacuum at wide open throttle (WOT). This vacuum helps pull air through the carb, increasing its cfm.
Is a sticky valve better than a full on race engine?
An engine with a sticky valve will be even less efficient than if it was working properly. A full-on race engine could actually exceed 100 percent efficiency, but let's assume street engines for this exercise. When you look at a dyno graph and see peak torque, that's the engine's most efficient moment.
Does vacuum increase CFM?
This vacuum helps pull air through the carb, increasing its cfm. If your engine has more, or less, vacuum than this at WOT, then your flow numbers will be different (more WOT vacuum will increase the cfm a bit, while less will decrease it a bit). As you can see, picking the right carb for your engine isn't rocket science, but it is science, ...
How does a vacuum secondary carburetor work?
Vacuum secondary carburetors have one accelerator pump and work off sensing the engine load, which progressively open the secondary butterflies as rpm increases. A mechanical secondary carburetor uses mechanical linkage to open the secondary butterflies and most also have dual accelerator pumps (a.k.a. double pumper).
What is the volumetric efficiency of a stock engine?
Any ordinary stock engine will have a volumetric efficiency of about 80%. Most rebuilt street engines with average bolt-ons have a volumetric efficiency of about 85%, while race engines can range from 95% up to 110%.
Can too much carburetor hurt your engine?
Unfortunately, too much carb is a common mistake that can actually hurt the overall performance of your engine. The right idea would be to match the carburetor to the engine's breathing ability or volumetric potential. The engine's volumetric efficiency is a measurable value and with a correctly matched carburetor, ...
