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  1. mayhugh1

    1/3 Scale Ford 289 Hi-Po

    The compression ratio using the measured combustion chamber volume worked out to be 6.9. I was hoping for a little more so the pistons could be simply dished to provide the needed valve clearance. At five to ten thousandths interference the goal was a clearance of .050" to insure there would be...
  2. mayhugh1

    1/3 Scale Ford 289 Hi-Po

    Some twenty valves and valve cages were completed, and so there were plenty of spares. Cage leak-down times measured using the test valve were surprisingly consistent at some 15 seconds plus or minus a few. Ten seconds of polishing with extra-fine Timesaver smeared on a felt bob improved the...
  3. mayhugh1

    1/3 Scale Ford 289 Hi-Po

    Peter, I may have worked with 416 but my memory is foggy and most of the material I use is recycled scrap and machine shop drops with no pedigree behind them. It's possible I have some 416 in my shop as I have some drops that are bright and shiny like 303 with no corrosion but are magnetic. The...
  4. mayhugh1

    1/3 Scale Ford 289 Hi-Po

    Sparky, The valve heads are 3/8" in diameter and the stems are 5/32" in diameter. If I understand your question, the leak check isn't trying to measure a component of leakage between the cage and the valve stem because it doesn't affect the main seal of the combustion chamber. I typically leave...
  5. mayhugh1

    1/3 Scale Ford 289 Hi-Po

    It's difficult to separate the design and machining of the valves from those of the valve cages. In addition to sealing the combustion chambers they affect their volumes (and C.R.) as well as the rocker arm geometries and pushrod lengths. Even with their CAD models playing nicely together...
  6. mayhugh1

    1/3 Scale Ford 289 Hi-Po

    My last photo showing the 'assembled' camshaft may be misleading. The camshaft parts was really just stuck together for the photo. The body with all the lobes is separate from the front hub. These two pieces have tenon'd ends which will be Loctite'd together inside a sleeve which will be...
  7. mayhugh1

    1/3 Scale Ford 289 Hi-Po

    The camshaft was tackled next. Ninety degree heads, offset cylinders, interleaved pushrods, firing order, direction of rotation - all these combine to make the scratch design of a V8 camshaft a challenging mental exercise. First up was the selection of the camshaft's duration and lobe...
  8. mayhugh1

    1/3 Scale Ford 289 Hi-Po

    Petertha I used the term hi-rel to mean high reliability. The bearings are .250" dia and .223" wide including the shoulders. I've never before seen bearings with these raised shoulders, and that was one of the reasons why I bought them. They were a one-off lot purchased from the CDD Surplus...
  9. mayhugh1

    1/3 Scale Ford 289 Hi-Po

    Although I hadn't yet gotten to the valves and valve cages, I needed a break from the mind-numbing valve train parts production. To ease the monotony, I prototyped a pair of roller lifters to see if a roller camshaft could be made to work in this engine. Of course the lifters gained some...
  10. mayhugh1

    Seeking plans for twin cylinder inline i.c. engine

    https://www.homemodelenginemachinist.com/threads/draw-tech.29067/
  11. mayhugh1

    1/3 Scale Ford 289 Hi-Po

    The shaft will be pressed into place, and right now I'm not planning to harden either. The max lift will be .100". - Terry
  12. mayhugh1

    Resistor & grounding CDI ignition modules

    That resistor is to reduce the emi radiated by the plug wires. It's purpose is to reduce the Q (quality factor) of the inductance associated with the plug wires which can radiate interference to nearby electronics. It's more important in RC applications where the radios are susceptible. In our...
  13. mayhugh1

    1/3 Scale Ford 289 Hi-Po

    So many little parts ... One last revision of the rocker arms was prototyped before machining them en masse. They were then machined in batches of five with each from its own little 7075 workpiece. Small batches aren't very efficient, but they allowed fine tuning of the process without the risk...
  14. mayhugh1

    cylinder compression question

    As an interesting aside I recently watched a Youtube video of a guy trouble shooting a misfire in a particular cylinder in a new (full-size) engine. He was pretty experienced and suspected a compression problem in just that cylinder. The engine sounded normal and the battery current draw looked...
  15. mayhugh1

    1/3 Scale Ford 289 Hi-Po

    Tony, Yes, I've done it twice before. I really don't think it's a problem in a model, especially one that's using splash lubrication. But, we'll see. The question you should be asking is if an oil pump is really needed. If you could look through the oil pan of a running engine you'd wonder why...
  16. mayhugh1

    1/3 Scale Ford 289 Hi-Po

    Work started on the valve train, and with a couple hundred parts ahead of me I'll be a while. The valves' 5/16" diameter was locked in by the already machined heads. The intakes could have been bigger, but with the engine's huge plenum and long runners I was concerned about flow and manifold...
  17. mayhugh1

    Looking for inspiration

    photos? ... video?
  18. mayhugh1

    1/3 Scale Ford 289 Hi-Po

    Yes, I've used this on four of my engines and have been happy with the results. I didn't invent it - just offering an explanation of how it works. Terry
  19. mayhugh1

    1/3 Scale Ford 289 Hi-Po

    More Photos ...
  20. mayhugh1

    1/3 Scale Ford 289 Hi-Po

    Fixing the rub ... The bottom ends of the liners which stand .040" proud of the block created a couple thousandths interference with the sides of the rods that went unnoticed in the live assembly model. With the block stripped down and set back up in the mill, a quarter inch wide strip was...
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