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Thread: Safe Bore size Iron Eagle SBC

  1. #1
    Senior Member MASTER BUILDER
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    Safe Bore size Iron Eagle SBC

    I am planning a rebuild for Dart Iron Eagle SBC block and i want to order new pistons and have them on hand to save time. My question is what is the max bore size on a Dart Iron eagle block. Bore is now 4.155 and I want to go 4.185 for a few more cubes. If I order the pistons now and have them on hand I wont be down long on this rebuild. If I go 4.185 will I still have another boring left in it? Dart says at 4.185 wall thickness will be .275 or more.

  2. #2
    Senior Member EXPERT BUILDER
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    Why would you wany to go .030 when you can go .010 and leave 2 more bores before you get to 4.185. I really dony think with the same set-up on top you are going to see that much more power than a fresh bore of 4.165 will give you. Save the meat you will need it later .030 will only give you about 6 ci.

  3. #3
    4.200 is max bore with .200 wall thickness left

  4. #4
    Senior Member DYNO OPERATOR
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    Wall thickness is not the big issue. Head gasket sealing surface is.
    Small bore spacing blocks just do not have as much head gasket sealing surface between the bores.

    Ed
    " Let all things that hath breath, praise the Lord. Praise Ye the Lord" Psalms 150 vs 6.

  5. #5
    Senior Member MASTER BUILDER
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    So should I go about .010 or .015 over, we run alot of nos on this engine. I dont want to screw with this combo much, it has won 6 races this year already and 2nd or 3rd in the rest. I put my spare set of pistons in 3 weeks ago and need to order another set, I want to get them bigger so I can bore it next time. All the cylinders look great except #4 has some minor scarring from a burnt piston. I honed it out but I just aint happy with it. It takes about 6 weeks to get the pistons from Venolia and I want to go ahead and get them ordered so I can plan this rebuild during a time that we dont have any big races scheduled.

  6. #6
    Senior Member EXPERT BUILDER
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    I would go no more than .010 over, shuoldnt change your combination. I have a 565 and when it was time to freshen i went .007 over. In my opinion a little bigger bore woudnt change as much as a bigger stroke would.

  7. #7
    Member JUNIOR BUILDER
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    BRC Pistons

    Keep with the smaller bore. head gasket sealing will become an issue plus you have the option to freshen a couple more times before sleeving.

    Ed and I use BRC pistons, Depending on thr design most can be CNC'ed in days not weeks.

    e-mail me at
    [email protected]
    for more info.
    CDR Performance
    The Custom Engine Shop and Sponsor of the First Annual YellowBullet.Com Nats

    If you have never experienced fear your car isn't fast enough.

  8. #8
    Senior Member MASTER BUILDER
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    I would really like to try a piston set up like the one Ed designed for brc, if they would make it for a 4.155 bore SBC. I have been using Venolia pistons for years, but wouldn't mind trying something new.

  9. #9
    Senior Member DYNO OPERATOR
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    Yes,
    The same design concept is available for the SB Custom ordered pistons as well. What we or they are doing is to add additional strength into known weak areas of the pistons that show up with heavy nitrous usage. It does add some weight but in my opinon who cares. The added weight has been a non issue for me. At the same time all non essential or necessary weight gets removed by extra internal milling process.

    You can go through me, or you can go direct with BRC. The guy taking care of the Custom Order Tech now at BRC is Danny. Be sure you do give the dimensions of the rod from wrist pin to the end though becuase that extra space usually on most pistons gets filled with the thicker crown.

    www.brcperfromance.com

    Phone numer is here.

    1-800-522-7478

    I will come back a little later and will post some internal pics of the Bb Pistons of the first version we did and the newest updated and lighter 2nd version. I do like it much better and we lost non of the strength.

    These are not bullet proof. Don't get the wrong idea from me. I have seen the piston areas from tearing down engines built by others that were the damaged areas. I simply tried to make the more suseptible areas to be stronger and more resistant to damaging as easily.

    I have seen lots of damages that can not be prevented without a cam design change, engine design change, and more quality in the tuning department. Holes melted in the sides of the piston, all of the piston mangled in extreme heat or an explosion no one can make a piston to withstand.

    Ed
    " Let all things that hath breath, praise the Lord. Praise Ye the Lord" Psalms 150 vs 6.

  10. #10
    Senior Member DYNO OPERATOR
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    Guys I added this post to the sticky at the top so you can see there is a difference in what you are used to buying in custom pistons.



    Ed

    The BRC Nitrous BB Chevy type of Piston which works in Pontiac - Brodix Big Duke - Dart Big Chief and early DRCE1 combustion chambers. Different dome sizes available in this same profile and different valve angles and valve spacings available as needed for the exact application.

    As you look at the internal views you can see a few of the design changes and extra machining which set these pistons apart from many others for the same applications. You can not see any exact thicknesses or exact specs though. You can see some of the extra skirt strengthening and extra milling processes. You can see the fully shaped profile milled dome.

    WE have also done these in SB Chevys in either Dome, or Reversed Dome designs. Flat top would be easier but have not done it in flat top yet.

    Ed

    Ps;
    I have read and heard more than plenty of comments about me trying to re-invent the wheel etc. FYI. The wheeel has been re-invented countless thousands of times.



















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