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  1. #1
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    Default 245/265 hemi 6 carburetor

    What carburetor do you recommend for a 245/265 hemi 6 (thinking more 4 barrel then 2)

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    Hi
    stock 265 //5000rpm //90 % VE ==345cfm

    mild 265 // 6000 rpm //100 % ve ==460cfm

    race 265// 6500 rpm// 110 % ve ==550 cfm



    classic holley // quick fuel slayer 465 vac secondary
    or
    quick fuel HR 450 mech secondary

    The more drag race the car the bigger the carb with more rear gear// lighter car //more stall
    the opposite holds true as well
    The more street the smaller the carb less gear//std weight //less or stock stall

    A vac secondary is better for street
    A mech sec is better for drag

    What works for u may be completely different but there the guide lines
    Last edited by swampy; 28-03-2019 at 03:59 PM.

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    Quote Originally Posted by swampy View Post
    Hi


    A vac secondary is better for street
    A mech sec is better for drag
    I've always used mech sec for street... If you are at part throttle street driving you are on the primary circuit no matter whether it opens mechanically or by vacuum..

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    HI
    No doubt there is d/pumpers that can work but hey I did write

    A vac secondary is better for street
    A mech sec is better for drag

    What works for u may be completely different but there the guide lines

    A situation
    low revs tall gearing 3.08 etc
    low revs Part throttle to full throttle
    Then u go WOT
    d/p will open secondaries immediately
    Vac sec will respond better as primaries are the only one operating till vac sec needed

    D/p on the street will work if tuning time is invested in the carb unfortunately most donot.

    As I said b4 only thoughts basic advice which I feel answered the OP question .

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    The one Chrysler specified for it, 625 cfm Carter AVS. [ Air Valve Secondary ]. Small 1 7/16" primaries, large[r] 1 11/16" secondaries. Chrys used the same carb on 340s & 383s.
    When PHR magazine tested the small blocks in Feb 69, the 340 was the only s/b that made more hp than advertised, 295 v 275. It had the 625 AVS on it.

    The Chebbies, Ferds, Olds, Pontiacs all made much less than the adv hp.

    The new Edelbrock 650 AVS2 would probably be even better, it has annular pri boosters for even better response. Mate has used three of these, his one word comment on throttle response was: unbelievable.

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    Quote Originally Posted by swampy View Post
    HI
    No doubt there is d/pumpers that can work but hey I did write

    A vac secondary is better for street
    A mech sec is better for drag

    What works for u may be completely different but there the guide lines

    A situation
    low revs tall gearing 3.08 etc
    low revs Part throttle to full throttle
    Then u go WOT
    d/p will open secondaries immediately
    Vac sec will respond better as primaries are the only one operating till vac sec needed

    D/p on the street will work if tuning time is invested in the carb unfortunately most donot.

    As I said b4 only thoughts basic advice which I feel answered the OP question .
    Yeah and you'd have to screw around with the vacuum in the VAC SEC and invest time in tuning both the primary and secondary circuit too... With a mechanical secondary you give it a shot with the accelerator pump discharge nozzle or squirter and its instant...

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    Drummo,
    Edelbrock tested the popular Holley 6619 600 cfm vac sec carb against a 625 Carter AFB on a 350 Chev. [ The AFB & AVS have the same pri, secs slightly different ]. The AFB made 17 ft/lbs more tq, 17 more HP...& used less fuel doing it. If you would like a copy of the dyno sheet, PM me an email address. Anyone elsde also, PM your email.

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    Edelbrock testing a Carter against a Holley, throw that test into the bin.

    I like these kind of tests from independent sources, if truly independent tests are carried out anymore......

    I ran a Carter/Edelbrock thing years ago, the day I pissed it off was a great day.

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    Quote Originally Posted by HQ 368 View Post
    Edelbrock testing a Carter against a Holley, throw that test into the bin.

    I like these kind of tests from independent sources, if truly independent tests are carried out anymore......

    I ran a Carter/Edelbrock thing years ago, the day I pissed it off was a great day.
    Dont tell Geoff that ...

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    HQ,
    Maybe your tuning skills leave a lot to be desired....

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    Quote Originally Posted by GtoGeoff View Post
    HQ,
    Maybe your tuning skills leave a lot to be desired....
    Absolutely, I dont regard myself as a tuner, I'm a knucklehead. All my life working in powertrain and I still know nothing.
    We played with it for 6 months or so in spare time and a few dyno sessions, it was better than the twin gas research throttle bodies on it prior.
    I Probably should have bought a Predator instead of that POS....

    The alternative made more power through the range but the improved dive ability out of corners and roundabouts was greatly improved.

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    hi
    As the topic is ""well"" discussed what ever carb fitted it needs to be tuned properly ,not by some one who knows a guy who guesses . For most if the tuner does not have an A/F gauge walk away. Buying the carby is only half the story , good fuel supply ,good air supply and good tuning ,good install is all required .

  13. #13
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    Quote Originally Posted by swampy View Post
    hi
    For most if the tuner does not have an A/F gauge walk away.
    You can do it the olf fashioned way and have a look at the spark plugs after a WOT run...

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    Quote Originally Posted by paulzig View Post
    You can do it the olf fashioned way and have a look at the spark plugs after a WOT run...
    Not too many around that can do that, these days.

    Makes you wonder how racers of yesteryear, ever won any races without an A/FR wide band setup, as it seems if you don't have one, you can't tune?

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    Hi
    Tuning was easier when there was lead in the fuel . Ya need tobe old enough .The fuel was cheap and actually worked Ah they were the days!!!!

    Part throttle cruise
    part throttle acceleration
    power valve operation set point
    set secondary activation

    You spend a lot of time accelerating on the street . Not all the time at 8000rpm

    Better to set with A/F gauges , been in workshops since the seventies . Engine makers have had them way longer than that . Although wide band oxy sensor is more accurate than the old style sensors .

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