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Thread: Carb Selection

  1. #1

    Default Carb Selection

    Hello all, I'm about to get my '67 GTO fired up, looking to put a new carb on my Edelbrock 2156 manifold. The Pontiac 400 has the stock "670" heads, 068 "S" Crane blueprint cam, HEI ignition, headers, TH400 with a 2200 stall & 3.36:1 gears. Not sure, as the carb selector says 4175 series spread-bore Part# 0-80555C, or if I need a 750 CFM. Prefer single inlet. I plan on using the car on weekends, and as a daily driver during the warm months. Any thoughts appreciated.

  2. #2
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    Since you have a dual pattern intake manifold (square-bore/spread-bore carburetor mounting), you might get more replies if you specify which carburetor type you want.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  3. #3

    Default

    Spread-bore is preferable, so I do not require the adapter plate, but square-bore has more options. I'm looking for a drop in solution, easy setup, and something that does not require constant tinkering.

  4. #4

    Default

    Quote Originally Posted by gassman_67 View Post
    Hello all, I'm about to get my '67 GTO fired up, looking to put a new carb on my Edelbrock 2156 manifold. The Pontiac 400 has the stock "670" heads, 068 "S" Crane blueprint cam, HEI ignition, headers, TH400 with a 2200 stall & 3.36:1 gears. Not sure, as the carb selector says 4175 series spread-bore Part# 0-80555C, or if I need a 750 CFM. Prefer single inlet. I plan on using the car on weekends, and as a daily driver during the warm months. Any thoughts appreciated.
    Well, carb selectors usually base there selection on cam performance/motor size, etc, etc. A 400 cu in motor would be happy with anything from 650 cfm - 850 cfm. Obviously, the 650 cfm being a little the small side, and 850 cfm being a little on the big side for a stock motor. When looking at carburetors from strictly a CFM standpoint, be aware that a smaller cfm carb won't peak rpm wise as much as a bigger CFM carb will. A smaller carb has smaller bores, and therefore is affected a little more by the vacuum signal vs a larger carburetor.

    With you stating this is a daily driver, and used on weekends, I would get an electric choke based carb with mechanical secondaries. I personally like the mechanical secondaries, you have enough performance to where it shouldn't give you any issues. That's just me, I like the mechanical secondaries. It wouldn't be wrong to run a vacuum secondary either. It would work just fine with your setup. I would personally run a 750 cfm. Gives a little room for growth performance wise, and still run great at idle and upper rpm. I ran a 750 cfm double pumper on a 383 with no issues. Idled good and easily revved in the 6500+ rpm range.

    Look in the classic Holley or double pumper. Have been a some "tunability" issues with the Street Avengers.

  5. #5

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    Thank you!

  6. #6
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    Quote Originally Posted by 69cam View Post
    I would personally run a 750 cfm. Gives a little room for growth performance wise, and still run great at idle and upper rpm.
    I was thinking the exact same thing.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  7. #7

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    Quote Originally Posted by Danny Cabral View Post
    I was thinking the exact same thing.
    Do you have a model number in mind?

  8. #8
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    Quote Originally Posted by gassman_67 View Post
    Do you have a model number in mind?
    Personally, I like the 750 cfm Street Demon carburetor (especially for a daily driver & cruiser). It's the same basic type of carburetor as the Edelbrock Thunder Series AVS units (dual bolt pattern, mechanical/air valve secondaries, metering rods, etc.).

    Before my EFI conversion, I owned both brands of carburetors. The Holley definitely has more tuning capability, and therefore, has the potential of better optimizing a competition tune. If it were a street/strip or racing application, a Holley 4150 would be the appropriate carburetor. The Street Demon & Edelbrock carburetors are simpler, easier to tune, very reliable, offer good driveability, and cost less. I also got better fuel economy from this type of carburetor, and they held a tune better too.

    http://www.holley.com/applications/C...bSelection.asp (Interactive Carburetor Selector)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

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