Planning an Engine Build for Altitude

Small Block Mopar Engine

  1. jau126

    jau126 '65 Dart GT 273 904

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    Joined:
    Jun 7, 2020
    Location:
    Salt Lake City, UT
    Local Time:
    2:50 AM
    Being at elevation is putting the small block (273) under dog sucking for wind at 4500 ft. I am trying to wrap my head around what a build tailored to the altitude would look like. I know the cam choice will be critical up here as to not over cam it and loose all the low end. (We have seen this play out in multiple threads.) However, I would want the engine to be able to run at sea level without reworking the entire motor. My thought is either a cam change or a head gasket change. (Thinking a .028" X 4.08" to the standard felpro permatourqe or something along those lines.)
    What I am not exactly sure about when playing with the Wallace racing calculator if I am still limited to a 10 SCR for Iron Cylinder heads when I will end up with less then 8.0 DCR considering the altitude and cam choice. I have played around with some hypothetical Intake valve closing angles and that of the E-4. Heck, I even though about the stock 2 barrel cam with some bump in SCR points.
    I personally do not have any intentions on driving it to see level but you never know who will own the car next.
    Other details about this:
    Flat Top Pistons with Deck and heads milled as needed for CR and flatness.
    3.55 out back with a stock or very close to stock stall. (*EDIT:: it is still a 7 1/4 out back and I do not want to break the thing. No there is not money or capability to switch to an 8 3/4. Part of the reason a 408 is out of the cards.)
    And I do not want to be reminded of a Blue Print 408s, 318s etc. because that is the logical way to go.
    (If one of you guys buy this thing, as it is currently listed for sale here, then this will never happen and you will save me from my own stupidity.)
     
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