whats a CHEAP, yet decent carb/intake for my 383/400sbc



whats a CHEAP, yet decent carb/intake for my 383/400sbc

Postby grumpyvette » January 14th, 2010, 4:56 pm

"whats a CHEAP, yet decent carb/intake for my 383/400sbc"

most of us are on tight budgets, I know I an most of the time

http://www.j-performance.com/index.php? ... view&id=27

the CORRECT answer to that question depends, on factors like the carb,transmission and rear gearing you've used and if your using headers,and what cam your using etc. if your engine spends most of its power band below 6000rpm a decent dual plane intake is indicated, in many cases a edelbrock rpm air gap or weiand air strike matched to a 650-750cfm carb is a good choice for street/strip performance applications

http://www.holley.com/0-3310C.asp
Image
youll be hard pressed to beat your performance on a basic , 350-383 hydraulic cam engine, with a HOLLEY 750 vacuum secondary carb for both ease of tuning and low cost ,high value in most street cars looking to make under about 450hp.
and a decent street/strip intake that matches is the
8501 - Weiand Intake Manifold
Image
when you select an intake manifold the goal is usually to maximize the engines volumetric efficiency, in the engines intended power band,(how efficiently you can fill the cylinders with a full fresh charge of fuel/air mix)
Image


dual plane intakes almost always produce better average power in the 1500rpm-6000rpm range, while single plane intakes rarely equal or produce better hp until about 4000rpm, but by about 5500rpm the power produced tends to be similar in the 383-400sbc , after about 6000rpm theres generally a trend showing the better single plane designs having better flow rates PROVIDED the heads and cams selected, are also designed to maximize the higher average power band.
many people are surprised to find the dual plane intakes, work as well as they do with the larger duration cams, theres a link below youll find interesting keep in mind that in most cases the fuel pressure at the carb inlet port NEEDS to read 4.5-5 psi MAX and you NEED to set the float levels per the carb manufacturers instructions, having the pressure , higher at for example 6.5 psi will in many cases cause the needle & seat valve to constantly leak excess fuel, into the carb while the engine runs


http://www.holley.com/8501.asp
Image

http://www.summitracing.com/parts/HLY-65-3310/

this is what ID use on a street 383/400 in many applications as it gives you good value for your money,


now with better heads,more compression, a more radical cam with more than about 235 dur. at .050 lift, a 3.73:1-4.56:1 rear gear etc, this intake below might be an option., but too take full advantage, of the single plane intake design and flow youll need to spend most, of your time in the 4500rpm-7500rpm plus power band

http://www.summitracing.com/parts/HLY-300-110/
Image


Im sure youll find these threads of interest


viewtopic.php?f=44&t=392&p=5415&hilit=+test+intake#p5415

viewtopic.php?f=52&t=322

viewtopic.php?f=55&t=2857

viewtopic.php?f=52&t=333

viewtopic.php?f=52&t=148

viewtopic.php?f=55&t=2953

viewtopic.php?f=52&t=462

viewtopic.php?f=55&t=858

viewtopic.php?f=44&t=773

http://www.carcraft.com/techarticles/se ... index.html

http://www.circletrack.com/ultimateraci ... index.html

http://www.circletrack.com/enginetech/c ... index.html
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: whats a CHEAP, yet decent carb/intake for my 383/400sbc

Postby grumpyvette » January 18th, 2010, 4:27 pm

http://www.jegs.com/i/Holley/510/12-803BP/10002/-1
Image

thats a dead head style regulator (above) and its FAR FROM IDEAL, all QUALITY return style regulators that Ive seen, have THREE PORTS

(1)FEED from tank
(1)CARB feed line
(1)RETURN to tank
and a pressure adjustment screw, and a vacuum line connection to the plenum

if your running a carb, you need to have a correctly set up fuel system, one of the more common complaints is related to fuel pressure at the carb inlet port, many fuel pumps produce 6-12 psi of fuel pressure at higher rpm levels , some even provide that at idle speeds, that much pressure tends to flood carbs and make float adjustment difficult or useless, only 7-9 psi will almost always overcome the needle & seat and constantly flood the carb, that is probably the source of your major problem,if the carb won,t adjust and runs rich, install a RETURN STYLE fuel pressure regulator, and a line back to the tank or at least back to a TEE thats located before the pump intake point

http://www.jegs.com/webapp/wcs/stores/servlet/category_10001_10002_10019_-1_10267?sendroicid=bbef8492-2d00-41d6-b158-38db0de2603c&sendroiad=3824188001&sendroikwd=Fuel+Line&gclid=CNrLsez3opkCFQudnAodtC_cpQ

Image
yes the diagram says 8PSI your far better off with 5 psi in most street car applications

these cheap ones, that are dead head style seldom work well

http://www.jegs.com/p/Holley/745059/10002/-1

much better
http://www.jegs.com/i/Mallory/650/4307M/10002/-1

http://www.jegs.com/InstallationInstructions/600/650/650-4307M.pdf

Image
http://www.summitracing.com/parts/MAA-4309/

High-flow for your fuel system.

When using high-pressure fuel pumps, a fuel pressure regulator must be installed to prevent carburetor flooding. These Mallory fuel pressure regulators feature housings fully machined from 6061-T6 billet aluminum, and specially designed high-flow fuel passages. These features, combined with a quick-acting diaphragm assembly, make them extremely efficient. A mounting bracket is provided to allow quick and easy mounting.


http://www.summitracing.com/parts/MAA-4307M/
Image

http://www.summitracing.com/parts/AEI-13351/
Image

http://forum.grumpysperformance.com/viewtopic.php?f=55&t=635
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Posts: 14105
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Re: whats a CHEAP, yet decent carb/intake for my 383/400sbc

Postby Dustytrix » January 18th, 2010, 9:27 pm

I needed that info on fuel regulators, I just put a new elec fuel pump in my camaro gas tank. Its for a tpi intake and I will be going carb with this new motor. I am not sure but I think the pump is pushing 45lbs for tpi. I saw where the regulators would adjust up or down for pressure going out. My question is does it matter how much pressure is feeding into the regulator?
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Posts: 79
Joined: September 19th, 2009, 9:39 pm

Re: whats a CHEAP, yet decent carb/intake for my 383/400sbc

Postby grumpyvette » January 18th, 2010, 11:27 pm

pressure is the way you measure resistance to flow, in general fuel pressure regulators will operate correctly within a pressure range they are designed for, in the case of carbs, fuel pressure from about 14psi too about 8 psi is whats expected to be supplied from a carb style fuel pump , and expected to be dropped to a 5-6 psi range at the carbs inlet port
on fuel injection the average pressure range is far higher , at about 45-75 psi supplied from the pump, to the regulator and dropped to about 40-60 psi at the fuel rails supplying the injectors in most common EFI systems.
now obviously there will be guys wanting to adapt a EFI fuel pump to a carb application, and in most cases thats not going to work all that well long term due to the fuel lines flow characteristics and pressure curve the components are designed for so in an ideal world you plumb the system with matched components and install a fuel tank/ fuel cell and lines of the correct size and pressure range, can you use a EFI pump to supply a carb? yes IVE seen it done with TWO regulators in series on an AN8 feed line and two separate AN8 return lines going back to a fuel cell, so yes it can be done, but its not ideal and use of the correct parts works better, these threads may help.

viewtopic.php?f=55&t=211

viewtopic.php?f=55&t=635

viewtopic.php?f=55&t=733

viewtopic.php?f=55&t=1939

viewtopic.php?f=55&t=1030

viewtopic.php?f=55&t=231
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Posts: 14105
Joined: September 14th, 2008, 1:40 pm
Location: florida

Re: whats a CHEAP, yet decent carb/intake for my 383/400sbc

Postby grumpyvette » February 5th, 2010, 4:37 pm

whats the best carb size?

http://www.4secondsflat.com/Carb_CFM_Calculator.html

http://www.gtsparkplugs.com/CarbCFMCalc.html

http://users.erols.com/srweiss/calccarb.htm

ok lets look at things logically, youll want to provide a constant air flow rate matching the engines potential max rpm,requirements at W.O.T. but have decent off idle response, and decent mileage on most cars,
a 350 spinning about 6500rpm which is a reasonable upper rpm limit for use of flat tappet hydraulic lifter can at least in theory digest 350 x 6500rpm/2 or about 657 cfm, on a 406 that would change to 406 x 6400rpm/2= 751 cfm, but keep in mind theres potential restrictions to air flow and the draw rates at the carb are computed at a constant vacuum, but on an engine theres not at a consistent plenum vacuum signal, now having run both the 600cfm and 750 cfm carbs on many 350-383 displacement engines Im forced to point out the rather obvious fact that the vacuum secondaries on the holley carb will by design compensate for the engines needs, and regulate the flow into the plenum, and that max power is almost always reached at an air fuel ratio between 12.4:1-and 12.8:1 and at a vacuum reading in the plenum near the 1.5" to .05" of vacuum at W.O.T.
you might also consider that a well tuned set of headers and a matched cam can and frequently do require a carb that can supply slightly over 100% OF THE ENGINES VOLUMETRIC EFFICIENCY AT W.O.T.

the holley 750 cfp covers that range very effectively

you might want to read thru these links for related info

viewtopic.php?f=44&t=777

viewtopic.php?f=44&t=392

viewtopic.php?f=44&t=1788

viewtopic.php?f=44&t=773

viewtopic.php?f=44&t=1116

viewtopic.php?f=44&t=634

viewtopic.php?f=44&t=384

viewtopic.php?f=55&t=444&p=5682&hilit=quads#p5682
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Posts: 14105
Joined: September 14th, 2008, 1:40 pm
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