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  • Engine: 289 Compression test

    Hello,
    I have a 289 free flow engine, it's had a re-build with a hone & new rings, what numbers would I expect on initial compression test with zero miles?

    regards, Cus
    sigpic

  • #2
    I would not worry about the engines compression, I assume you mean "cranking" compression. I'd be more concerned with "leak down" values. These mean MUCH more, overall to engine health than cranking compression.
    Either way, with zero miles, the numbers will most likely be all over the proverbial...map.
    Wait until you have at least 500 miles on it before being concerned about any values. Otherwise, you'll just drive yourself crazy asking...why..?

    Mike

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    • #3
      Originally posted by Cus63 View Post
      Hello,
      I have a 289 free flow engine, it's had a re-build with a hone & new rings, what numbers would I expect on initial compression test with zero miles?

      regards, Cus
      Not enough information:

      1. What was the cylinder wall taper after the hone? Stone or diamond finish?
      2. What was the piston-to-wall clearance?
      3. New pistons or re-used?
      4. Cast, moly or chrome rings?
      5. Ring end gap?
      6. Heads milled? Thin or thick head gasket?

      Jack Vines
      PackardV8

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      • #4
        Won't be real high as the rings aren't seated and usually valves aren't either unless they were lapped. My WAG is 90 to 100 psi

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        • #5
          Thanks for the replies,
          the engine is a low mileage 289 with standard bore, hone & new rings etc. not sure of the specifics, it's running like a top, but will be a while before it hits the open road,
          I got 105 - 113, I was just curios to see what others had after re-build. I realise it needs to be run in & things will hopefully improve,

          regards, Cus
          sigpic

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          • #6
            Thanks; knew this was a question SOMEBODY had already asked (multiple times? :-) ). Just for confirming data, my 289 Golden Hawk last night showed abot 110-120psi while cranking (only checked two cylinders). Figured I'd check for fun while cranking for the first times and correcting some oil-fitting leaks. I completely rebuilt mine (6 years ago! :-( ) with new pistons, rings, over-bored .020 from std, and valves. No idea what they did for honing and such (machine shop did only that plus valve seats and fitting new valves). I carefully filed the new rings to spec gap, etc.. Copper Fel-Pro gasket (is that thick or thin? didn't know there was a difference). But about as close to factory-fresh as I know how to make it. And liberally dunked pistons in oil at assembly, and regularly have turned the engine over with a wrench to keep those cylinders from any chance of corrosion in our freeze-thaw Minnesota cycles. I know 130-150 is "normal" AFTER IT BREAKS IN and rings seat, but was also curious what one should hope for "unbroken-in" like this. So, I appreciate that information. And, not worrying about it. Enough OTHER things to worry about. Still hoping to actually figure out how to "minimally" wire it up here, put some gas in the tank for the first time, and see if it starts. Still just a chassis, once I know it starts and semi-runs will put the radiator on, and..... GULP, finally time after 10 years to figure out what to do with that body sitting on its cart off to the side in the shop!
            Happy Thanksgiving everyone! A strange one with COVID, but that would be this whole year. Hope all are staying healthy, physically AND mentally.
            Barry

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            • #7
              Originally posted by Cus63 View Post
              Hello,
              I have a 289 free flow engine, it's had a re-build with a hone & new rings, what numbers would I expect on initial compression test with zero miles? regards, Cus
              Your Engine has had an "OVERHAUL", or "Freshening" if Valves and Bearings were not done.
              I would be pretty upset if someone Sold me a car advertised as having a "Rebuilt" Engine, but did not have the whole Nine Yards!
              StudeRich
              Second Generation Stude Driver,
              Proud '54 Starliner Owner

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              • #8
                Originally posted by StudeRich View Post

                Your Engine has had an "OVERHAUL", or "Freshening" if Valves and Bearings were not done.
                I would be pretty upset if someone Sold me a car advertised as having a "Rebuilt" Engine, but did not have the whole Nine Yards!
                Sorry Rich, car is not For Sale! My engine was completely stripped down & rebuilt as quoted.
                sigpic

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                • #9
                  Click image for larger version  Name:	P7080834.JPG Views:	0 Size:	109.5 KB ID:	1866715

                  Hi Cus, this is what I got from my 90K+ odometer listed engine. I don't know if it's ever been apart though.

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                  • #10
                    Thanks Topper,
                    I'll wait till my engine is run-in & re-test, looks like yours is around 132, which I'm thinking is pretty good at 90k,

                    regards, Cus
                    sigpic

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                    • #11
                      When you're satisfied with the break-in, here's how to properly test cold cranking compression:

                      1. Fully charged battery.
                      2. Remote cranking switch.
                      3. Disconnect coil.
                      4. Remove all spark plugs.
                      5. Block open choke and carb throttle butterflies.
                      6. Screw in the compression gauge to #1 cylinder.
                      7. Push the remote starter button and count five compression strokes.
                      8. Write down the result before moving to the next cylinder.

                      jack vines
                      PackardV8

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