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Valve Spring Removal - Bad Idea?

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  • #16
    Based on diameter and length, these look like they should work, and the price is right. If I don't find anything local, I'll give them a try.

    http://www.summitracing.com/parts/MOR-62380/
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    Track Car Build | COM Sports Car Club

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    • #17
      Originally posted by Brendan View Post
      Based on diameter and length, these look like they should work, and the price is right. If I don't find anything local, I'll give them a try.

      http://www.summitracing.com/parts/MOR-62380/
      There ya go Brendan. I may have to give those a try. Thanks for the link!

      Jake

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      • #18
        And a decade later I have 2 questions.

        1. Is this tool still the go to or has anyone found something better to use? Or does everyone just take the box off anyway now?

        2. Did Jake ever build the tool to check PV clearance with only valve cover removed?

        Thx


        P.S. (from the other decade old threads it appears the shrick 284/276 cams are not worth it with stock pistons due to PV clearances and having to jack up timing to make them work / evo's don't do enough either.. Still the consensus?)

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        • #19
          On that note I have two questions.
          1. What is the ideal safe piston to valve clearance.
          2. What is the minimum clearance.

          Thanks, Dave.

          E30 M3 1987
          Mini Clubman GT
          BMW E36 323 Msport
          Toyota Corona
          KTM 200EXC
          Honda CB50 (1979)

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          • #20
            There's no one answer to that Dave. It depends on your valve springs, cam profile, redline, and other factors.

            On my first build, I had .065" minimum clearance on the exhaust side. That was with Schrick 284/276 and Sport Evo valve springs. I never had a problem, but when I rebuilt the motor I found marks on the #4 piston showing that the exhaust valves had made contact. So with those parts and a 7500 redline, I would say that .065" was absolute minimum.

            I have read that with motorsport springs and cams....you can go as low as .040".

            On my current build, I decided I wanted to sleep better, so I used pistons with huge reliefs and have around .120" clearance.
            Last edited by Ironhead; 01-04-2020, 02:09 AM.

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            • #21
              Originally posted by Ironhead View Post
              There's no one answer to that Dave. It depends on your valve springs, cam profile, redline, and other factors.

              On my first build, I had .065" minimum clearance on the exhaust side. That was with Schrick 284/276 and Sport Evo valve springs. I never had a problem, but when I rebuilt the motor I found marks on the #4 piston showing that the exhaust valves had made contact. So with those parts and a 7500 redline, I would say that .065" was absolute minimum.

              I have read that with motorsport springs and cams....you can go as low as .040".

              On my current build, I decided I wanted to sleep better, so I used pistons with huge reliefs and have around .120" clearance.
              How do you take into account all the 'movement-stretch?' that is in the bottom end at TDC? there has to be some? the rod bearing clearance, the pin clearance, metal expansion when hot, etc etc. has to change the distance the piston gets to the head at redline?

              T

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              • #22
                Originally posted by HANDBLT View Post

                How do you take into account all the 'movement-stretch?' that is in the bottom end at TDC? there has to be some? the rod bearing clearance, the pin clearance, metal expansion when hot, etc etc. has to change the distance the piston gets to the head at redline?

                T
                I cannot imagine how you could calculate all that. I think the best you can do is go from experience others have had with similar builds. I got away with .065" on my first build, but made sure I upped the clearance on my second.

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                • #23
                  Originally posted by HANDBLT View Post

                  How do you take into account all the 'movement-stretch?' that is in the bottom end at TDC? there has to be some? the rod bearing clearance, the pin clearance, metal expansion when hot, etc etc. has to change the distance the piston gets to the head at redline?

                  T
                  I think that all gets taken into account with the minimum clearance. A static motor may have 1mm clearance but then when hot and at 8k rpm that clearance may be reduced to almost nothing.

                  My machine shop in Australia always worked with 1.2mm clearance (whatever that is in thou) and that is what I I would do as a min, but I have heard that BMW motorsport had min clearance of 0.8mm... you want to be 100% you know what you are doing with that clearance though... I would say with a closer PV you are getting better squish in the combustion chamber with no dead spots in the valve reliefs...

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                  • #24
                    Thanks guys
                    Excellent information no use experimenting with this best to be on the side of caution.
                    1.2mm = 0.047 “ so that might be too close for comfort with the S14, probably work okay with the GM and Ford V8.

                    E30 M3 1987
                    Mini Clubman GT
                    BMW E36 323 Msport
                    Toyota Corona
                    KTM 200EXC
                    Honda CB50 (1979)

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