Q about 781 bbc heads and limits of a cast crank
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Q about 781 bbc heads and limits of a cast crank

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    Senior Member H20MOFO's Avatar
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    Default Q about 781 bbc heads and limits of a cast crank

    I'm tempted to build the 100.00 2 bolt block(I'm going to get tommorow) with 781's,cast crank, and save my steel 427 arm, alum heads, 4 bolt block, ect,ect, for my 1 day blower build. Just curious what the limits of cast crank and a set of 781's are , and also the cc's of the 781's because if I can't use my pop ups, it no longer suites my disposeable budget. I doubt without a blower I'll see much past 500- 550 hp even with a solid roller cam. keep in mind I'm at 4500 ft .
    Last edited by H20MOFO; 08-12-2008 at 09:49 PM.
    Another Hot Boat refugee

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    [quote=H20MOFO;294723]I'm tempted to build the 100.00 2 bolt block(I'm going to get tommorow) with 781's,cast crank, and save my steel 427 arm, alum heads, 4 bolt block, ect,ect, for my 1 day blower build. Just curious what the limits of cast crank and a set of 781's are , and also the cc's of the 781's because if I can't use my pop ups, it no longer suites my disposeable budget. I doubt without a blower I'll see much past 500- 550 hp even with a solid roller cam. keep in mind I'm at 4500 ft .[/

    A Properly prepared set of 781"s will get you 5-550 H.P with a Solid Cam and 550-600 With a Small Roller (12.1 Comp ratio) cast crank is safe at 500 H.P.
    Jay

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    Quote Originally Posted by H20MOFO View Post
    I'm tempted to build the 100.00 2 bolt block(I'm going to get tommorow) with 781's,cast crank, and save my steel 427 arm, alum heads, 4 bolt block, ect,ect, for my 1 day blower build. Just curious what the limits of cast crank and a set of 781's are , and also the cc's of the 781's because if I can't use my pop ups, it no longer suites my disposeable budget. I doubt without a blower I'll see much past 500- 550 hp even with a solid roller cam. keep in mind I'm at 4500 ft .
    go for it ...u should have no trouble...i dont know the cc's rite off hand, but the 781's are good heads & the cast crank will work just fine...i dont think ur gonna wing the motor that hard!...getting 500/550hp is a stretch...maybe 450 max...clay the pistons to make sure they dont hit the valves & u should be able to use ur pop-ups...i wouldnt be afraid to run it...just my .02 cents

    FastRat

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    [quote=FastRat;294757]go for it ...u should have no trouble...i dont know the cc's rite off hand, but the 781's are good heads & the cast crank will work just fine...i dont think ur gonna wing the motor that hard!...getting 500/550hp is a stretch...maybe 450 max...clay the pistons to make sure they dont hit the valves & u should be able to use ur pop-ups...i wouldnt be afraid to run it...just my .02 cents

    FastRat[/quote

    781 cc's are 119
    Jay

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    cfm
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    Quote Originally Posted by H20MOFO View Post
    I doubt without a blower I'll see much past 500- 550 hp even with a solid roller cam. keep in mind I'm at 4500 ft .
    4500ft ? Ouch !

    No, you probably won't see that in real life. At or nor sea level maybe, but will take some compression and cam, headwork, and some rpm. WIll your block, crank, rods, etc be up for it ? Will require some money and prep and then depend on how you drive and etc.

    Hey, wait a minute. You should check locally to see if that 11.6:1 will be fine with pump fuel at your elevation. It just may be !

    I'm a flatlander so I don't know, but I'd check, and be willing to place a wager that you'll be okay with that compression if all else is in order.

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    Senior Member H20MOFO's Avatar
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    Thanks cfm I couldn't pull it off with iron heads, but I 've never been brave enougph to try it with the tin can heads. Also 91 is as good as it get's here. I guess the don't want all the peeps running the mormon 500 to go to fast.lol
    Another Hot Boat refugee

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