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Cylinder Head Compression Ratio

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  • Engine: Cylinder Head Compression Ratio

    I saw on Bob Johnstone's site that the 537555 heads have a chamber capacity of 54.5cc's. The compression ratio given is 8.00:1. Is that for a 259 or a 289? By the looks of the piston thru the spark plug hole it appears to have flat top pistons, so I can assume its a 259, but I want to see what compression ratio I really have. It needs a valve job (at least thats what I have determined so far) & if I have the heads milled, I dont want to get the compression too high.
    59 Lark wagon, now V-8, H.D. auto!
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  • #2
    Most specs for '57-'60 Cars with 537555 Heads AND THIN head Gaskets on either 259 OR 289 Engines come out the same due to the stroke, and show ABOUT 8.5 to one compression ratio, some charts do vary a bit. But remember that the same Heads on '55-'56 are 7.5 using the Stock THICK head gaskets. So you can safely mill them .030 or less and use the Thick gaskets and not have a pinging issue on the 87 Octane Unleaded fuel.

    That would be IF the heads have not been previously milled. As knowledgeable Machinist types here have said, it is best to measure the head THICKNESS to be sure, and I think Mike V or someone gave the numbers even, a BIG help.
    StudeRich
    Second Generation Stude Driver,
    Proud '54 Starliner Owner

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    • #3
      But do the heads need milling?
      HTIH (Hope The Info Helps)

      Jeff


      Get your facts first, and then you can distort them as much as you please. Mark Twain



      Note: SDC# 070190 (and earlier...)

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      • #4
        I dont know if the heads need milling Jeff. I havent removed them yet. But, if the volume of the cylinder is more with a 289, then wouldnt the compression ratio be higher? What I couldnt find is the "cc's" of a 259 or 289. With that all I would need to do is divide by 8 that would give the cc of each cylinder then see the "ratio" of that figure to the cc of the head.
        59 Lark wagon, now V-8, H.D. auto!
        60 Lark convertible V-8 auto
        61 Champ 1/2 ton 4 speed
        62 Champ 3/4 ton 5 speed o/drive
        62 Champ 3/4 ton auto
        62 Daytona convertible V-8 4 speed & 62 Cruiser, auto.
        63 G.T. Hawk R-2,4 speed
        63 Avanti (2) R-1 auto
        64 Zip Van
        66 Daytona Sport Sedan(327)V-8 4 speed
        66 Cruiser V-8 auto

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        • #5
          Originally posted by Warren Webb View Post
          I dont know if the heads need milling Jeff. I havent removed them yet. But, if the volume of the cylinder is more with a 289, then wouldnt the compression ratio be higher?
          Good thinking Warren, and you are absolutely right. The comp. ratio is kept at the same spec. on 289 engines by using dished pistons which has the effect of increasing combustion chamber area.
          "Burning Bridges...Lost Forevermore"......

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          • #6
            Thanks Dwain... I should slap myself in the head for forgetting the 289's have the dished pistons. This engine has the partial flow filter on it that was blocking the engine number, so today I took the filter off & see that its a 259 (engine # 3E17323). It is also a late 62 production so the full flow filter base is blocked off & it also has the dished freeze plugs. I'm going to put some oil in the cylinders tomorrow to see what the compression is. Right now doing it dry it has poor compression, yet with the plugs in, it turns over really slow, but when I pull them out, it spins freely. I'm thinking the starter might be the culprit there, so I'll pull the starter off my 61 & try that one since I know its good. Thanks Rich, Jeff & Dwain for your replies.
            59 Lark wagon, now V-8, H.D. auto!
            60 Lark convertible V-8 auto
            61 Champ 1/2 ton 4 speed
            62 Champ 3/4 ton 5 speed o/drive
            62 Champ 3/4 ton auto
            62 Daytona convertible V-8 4 speed & 62 Cruiser, auto.
            63 G.T. Hawk R-2,4 speed
            63 Avanti (2) R-1 auto
            64 Zip Van
            66 Daytona Sport Sedan(327)V-8 4 speed
            66 Cruiser V-8 auto

            Comment

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