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Thread: hp gain 40mm ckokes

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    hp gain 40mm ckokes

    Hi all
    Hp gain on 2 litre pinto from 38mm chokes to 40 mm chokes
    On twin 45mm weber side draughts cheers mariors2000.

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    Re: hp gain 40mm ckokes

    gut feeling, none! 1-2hp if your lucky, but happy to be proved wrong

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    Re: hp gain 40mm ckokes

    And maybe less everywhere - hole gets bigger, air speed goes down, less draw on jets, jets size goes up, all for no gain.

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    Re: hp gain 40mm ckokes

    A bit of feed back i gain an extra 5 miles a hour top speed down the 1/4 mile so the 40 mm chokes have gave me more top end power cheers mario.

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    Re: hp gain 40mm ckokes

    playing devils advocate was that because the old chokes were strangling the engine airflow wise, or was it rich and the new bigger chokes have leaned it out?

    i dont know much about drag racing, but given the change a 5mph gain sounds a lot to me

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    Re: hp gain 40mm ckokes

    playing devils advocate was that because the old chokes were strangling the engine airflow wise, or was it rich and the new bigger chokes have leaned it out?

    i dont know much about drag racing, but given the change a 5mph gain sounds a lot to me

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    Re: hp gain 40mm ckokes

    hi graham

    i fitted the 40mm chokes went from 145 mains to 150 mains and drop air corrector down to 170 from 180

    air fuel ratio is at 12.8 and was set like that before,

    i tune it myself done 4 passes at drags and im doing 90 miles at top speed

    before i was at 85 miles, graham im a mechanic by trade im learning myself motor feels strong to 7500 rpm i get it on the

    dyno so on to see how much more power it making cheers mario.

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    Re: hp gain 40mm ckokes

    150 main jet with 40mm chokes? Never seen that before.

    Also, did you do the runs with the 40mm chokes on the same day on the same track with the same tyres etc?

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    Re: hp gain 40mm ckokes

    Quote Originally Posted by Miniliteman View Post
    150 main jet with 40mm chokes? Never seen that before.

    Also, did you do the runs with the 40mm chokes on the same day on the same track with the same tyres etc?
    150 seems small to me, but its been a long while since i fiddled with carbs

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    Re: hp gain 40mm ckokes

    Yes on the same day 2 runs with smaller chokes then change to 40 mm chokes and check air fuel ratio im using f2 elm tubes thats why 150 mains engine had a narrow power band alot of you guys on turbosports are building rally motors not a engine for drag racing cheers mario.

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    Re: hp gain 40mm ckokes

    Q, if its a drag motor and all about pulling a zillion rpm right at the top end why 45mm carbs in the first place not 48's?

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    Re: hp gain 40mm ckokes

    Quote Originally Posted by mariors2000 View Post
    Yes on the same day 2 runs with smaller chokes then change to 40 mm chokes and check air fuel ratio im using f2 elm tubes thats why 150 mains engine had a narrow power band alot of you guys on turbosports are building rally motors not a engine for drag racing cheers mario.
    What camshaft?

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    Re: hp gain 40mm ckokes

    (double post)

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    Re: hp gain 40mm ckokes

    Quote Originally Posted by mariors2000 View Post
    A bit of feed back i gain an extra 5 miles a hour top speed down the 1/4 mile so the 40 mm chokes have gave me more top end power cheers mario.
    Also possible the bigger chokes gave you more max RPM, not extra power. In some races it can be an advance having the engine to running higher RPM's as where they make max power. Speedway and karting is an example. Even in rally it can happen, specially with 5 speed gearbox, if the engine is willing to run higher RPM's you can stay longer in a lower gear and be faster (not always).

    Drag racing is very special kind of racing. I can't give advice what would be best here.

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    Re: hp gain 40mm ckokes

    camshaft is 250 at .050 312 deg duration 103 lobe sep angle .500 lift

    cheers mario.

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    Re: hp gain 40mm ckokes

    camshaft is 250 at .050 312 deg duration 103 lobe sep angle .500 lift

    cheers mario.

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