Next topic for discussion - 990 heads
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Next topic for discussion - 990 heads

  1. #1
    Senior Member XClutchboy725's Avatar
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    Default Next topic for discussion - 990 heads

    Other than weight savings and the ability to inhibit detonation, do today's aluminum heads really flow substantially more than a good set of 990 heads?

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    Senior Member Boat 405's Avatar
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    Yes....try the flow sheets from AFR, Brodix, Dart.

  4. #3
    Hit it where you fit it
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    Quote Originally Posted by widowmaker View Post
    Yes....try the flow sheets from AFR, Brodix, Dart.

    RHS 320's are a solid head as well, 370 ish cfm @.700"

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    Senior Member XClutchboy725's Avatar
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    I think the cam is curently the bottleneck on my setup.

    Old school Offenhauser tunnel ram with dual 750dp Holley's (6109's)

    990 Heads

    Cam is the old Erson JB100 - 315 lift at the cam (542 at the valve) on both sides

    Duration is 235 @.050 on both sides

    Lobe centers are at 112 (I think!)

    I would like to change to a roller set up, open her up a bit, and still run wet headers!

    Good cam combo to do that with 990 heads out there?

    Old combo revved to 5700-5800 with fresh MPD pump (Stainless AT "B" with inducer)

    Would like to improve from there.....
    Last edited by XClutchboy725; 05-31-2008 at 10:50 AM.

  7. #5
    Swollen Member SinisterGrin's Avatar
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    Look at these flow numbers for Dart Pro 1's and you tell me if there is a big difference..................um.......that would be a yes.

  8. #6
    cfm
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    Newer heads not only flow more, but have better port and bowl shapes, cross sectional areas, , combustion chamber design, and some are developed with wet flow. Note: Merlin's are kind of excluded from this list, although a little better than stock.

    Most, not all, have raised exhaust ports and some raised intake ports.

    Alot has been learned since the 60's/70's.

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    Quote Originally Posted by cfm View Post
    Newer heads not only flow more, but have better port and bowl shapes, cross sectional areas, , combustion chamber design, and some are developed with wet flow. Note: Merlin's are kind of excluded from this list, although a little better than stock.

    Most, not all, have raised exhaust ports and some raised intake ports.

    Alot has been learned since the 60's/70's.
    Merlin's, is that because they are an older design or?

    Thought's on ProComp heads?

  10. #8
    I'm No Expert Shaun's Avatar
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    here's my flow specs from my 990's when i had them flowed.

    http://reitanfamily.com/misc/buildspecs.html

    My heads had minor port work and the intake valves are 2.25"

    You can see my build thread on hb http://hotboat.com/forums/showthread.php?t=126180

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    B.A.M aka "Black Azz Mike 396_Ways_To_Spit's Avatar
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    Hey Jeff! Finally pulling the mill to refreshen her up

    I would def step up in cam. You can achieve more with a better cam. Contact chris Straub on here and he can set you very straight with a nasty cam kit that will scare you!!!!! Talk with him about your top end kit I promise that you will be very happy
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    Senior Member XClutchboy725's Avatar
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    [quote=Shaun;197458]here's my flow specs from my 990's when i had them flowed.

    http://reitanfamily.com/misc/buildspecs.html

    My heads had minor port work and the intake valves are 2.25"

    That's what I was looking for! Some flow numbers to compare to.

    Thanks Shaun!

    I've checked out your build pics. Nice Job!

    Jeff

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    Senior Member XClutchboy725's Avatar
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    Quote Originally Posted by 396_Ways_To_Spit View Post
    Hey Jeff! Finally pulling the mill to refreshen her up

    I would def step up in cam. You can achieve more with a better cam. Contact chris Straub on here and he can set you very straight with a nasty cam kit that will scare you!!!!! Talk with him about your top end kit I promise that you will be very happy
    Yeah, She kinda forced me into it with the oil pump taking a dump on me.

    It's been a nice strong and reliable motor for years. Time to step up though....

    Thanks for the info!

    Jeff

  14. #12
    I'm No Expert Shaun's Avatar
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    just remember my 990's are not stock!

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    Quote Originally Posted by XClutchboy725 View Post
    Yeah, She kinda forced me into it with the oil pump taking a dump on me.

    It's been a nice strong and reliable motor for years. Time to step up though....

    Thanks for the info!

    Jeff
    Any question about which "out of the box" oil pump to use?.............MP
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  16. #14
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    Just keep in mind engine size and intended RPM.

    More flow is not always better. Beyond a point, it will hurt you.

    Here is a VERY hard running set of factory irons:

    2.19" intakes, 1.80" exhausts, on 11/32" stems
    Lift ---- Int----Ex
    .050 -- 31.8 -- 26.1
    .100 -- 67.2 -- 56.8
    .200 - 146.3 - 113.0
    .300 - 221.9 - 147.0
    .400 - 270.7 - 176.6
    .450 - 277.0 - 189.8
    .500 - 283.4 - 198.6
    .550 - 291.8 - 201.9
    .600 - 297.0 - 203.0
    .650 - 297.0 . 204.1

    That's better than 990's from the box, and mine are not rectangles, never were.

    Those produced a VERY hard running 454 that otherwise is "handicapped" by 8:1 compression and a hydraulic cam (and 1 too-small carb on a dual-plane Perf. RPM Air Gap intake).
    It makes 500HP at 5,400RPM, Aggressor B impeller in a Berk F, no inducer (but now blows the pump dry if I stomp it from idle (never did that before)).
    Spun her to 5,900 with the big nitrous jets 2 weeks ago teaching a TX driver a thing ot 2. LOL


    Just don't go TOO big looking at head flow unless you have a huge motor or intend to spin huge RPM.

    Something that fits will work wonders, something that does not, will require duct tape and bailing wire.
    "As democracy is perfected, the office of president represents, more and more closely, the inner soul of the people. On some great and glorious day the plain folks of the land will reach their heart's desire at last and the White House will be adorned by a downright moron."
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    The rest of us are being dragged along kicking and screaming.

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