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Recent content by yamoffathoo

  1. yamoffathoo

    Can IC Engine Compression Testing with/without Blanks on Inlet and Exhaust Manifolds Quantify Valve Leakage?

    Yes, see my response to Lou on Sept 19.
  2. yamoffathoo

    Can IC Engine Compression Testing with/without Blanks on Inlet and Exhaust Manifolds Quantify Valve Leakage?

    To those who gave this non-invasive, big end bearing gap measurement technique some thought, I encourage you to try it and see for yourself.
  3. yamoffathoo

    Can IC Engine Compression Testing with/without Blanks on Inlet and Exhaust Manifolds Quantify Valve Leakage?

    The main attraction of this test is that it can be done prior to purchasing a used car, in addition to all the other tests.
  4. yamoffathoo

    Can IC Engine Compression Testing with/without Blanks on Inlet and Exhaust Manifolds Quantify Valve Leakage?

    Thanks for the insights Brian, Both engines are 2AZ-FEXs, from 2007 Toyota Camry Hybrids. The "dead zone" just after TDC when there was angular motion and no piston movement showing on the dial gauge (accurate to 0.0005") was always repeatable and very symmetric for clockwise and...
  5. yamoffathoo

    Can IC Engine Compression Testing with/without Blanks on Inlet and Exhaust Manifolds Quantify Valve Leakage?

    Hey Lou, I was pleasantly surprised by the accuracy of this method. The engine I am assessing for refurbishment is a replacement for one that punched the #4 connecting rod bearing cap through the upper oil pan (casing) at 100,000 miles as the result of a radiator fluid leak. I tore that one...
  6. yamoffathoo

    Can IC Engine Compression Testing with/without Blanks on Inlet and Exhaust Manifolds Quantify Valve Leakage?

    Okay, Okay, I'll eat some crow on that idea...but here's another one (please see attachment). This quick measurement can detect excessive connecting rod big end bearing wear without having to disassemble and do the plastigauge routine as follows: 1) mount a 12" dia degree plate on the drive...
  7. yamoffathoo

    Can IC Engine Compression Testing with/without Blanks on Inlet and Exhaust Manifolds Quantify Valve Leakage?

    a), b) & c) would not be meaningful?
  8. yamoffathoo

    Can IC Engine Compression Testing with/without Blanks on Inlet and Exhaust Manifolds Quantify Valve Leakage?

    Thanks for all the suggestions, however since the engine is on the bench with inlet and exhaust manifolds removed I was hoping for comments about my fairly simple proposal to alternately blank the inlet and exhaust ports while cranking at 250 rpm: a) no lapping required if no peak pressure...
  9. yamoffathoo

    Can IC Engine Compression Testing with/without Blanks on Inlet and Exhaust Manifolds Quantify Valve Leakage?

    mfgenggear, Compressed air injection and leak down measurements would be heavily influenced by piston ring leakage. No detectible leaks past the valves would be perfect but how do I decide what is an acceptable leak rate?
  10. yamoffathoo

    Can IC Engine Compression Testing with/without Blanks on Inlet and Exhaust Manifolds Quantify Valve Leakage?

    I am considering refurbishing a 200,000 mile 2.4L, 4 cylinder engine sitting in my shop. Compression testing at 250 rpm yields 90 psig, which increases to 120 psig with 3 squirts of oil in the cylinders, which is below the 140 psig minimum. To determine whether inlet and exhaust valves are...
  11. yamoffathoo

    Experiments with "Constrained Layer Damping" of Small Bore Connections

    This post is an extension of my project to dampen the dynamic response of a 1/2"dia stainless steel tube x 40" span in a clamped-pinned configuration that fails in fatigue after 2 years operation. So far the composite manufacturers I have contacted don't determine damping coefficients for their...
  12. yamoffathoo

    Experiments with "Constrained Layer Damping" of Small Bore Connections

    A British Firm (GL Industrial Services UK Ltd.) was experimenting with composites to dampen the dynamic response of small bore connections to compressors with the handle "Constrained Layer Damping". This investigation was completed in 2019, but the Final Summary Report is a little sparce on...
  13. yamoffathoo

    How to calculate the equivalent stiffness of concentric, composite tubes in bending?

    Thanks Greg, I received an E.Mail notification with your response which included the following statement at the end: "You don't have to wrap the whole tube evenly, the maximum bending and least impact from the mass loading is at the root." This statement does not appear in the text...
  14. yamoffathoo

    How to calculate the equivalent stiffness of concentric, composite tubes in bending?

    Thanks Greg Locock, This 40" length of tube is responding to a process pulsation that caused the tube-to-nozzle weld (at the anchored end) to fail in fatigue after 2 years of continuous operation that subsequently caused loss of production to make the repair. The 40" span is not close to walls...
  15. yamoffathoo

    How to calculate the equivalent stiffness of concentric, composite tubes in bending?

    My apologies - trimmed the Rules by accident.
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