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Thread: Vertical hit and miss engine

  1. #31
    Join Date
    Mar 2008
    Location
    Barrie, Ontario, Canada
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    Cylinder head-3 Cylinder head has been parted off from the parent material, then flipped over and remounted in the 3 jaw chuck, to be taken down to finished overall height of 0.80" Once it is faced to exact length, the exposed face is machined 0.050" deeper, and a 1.00" spigot left in the center. Next step will be over to the rotary table to finish off what is now the exposed surface.
    Brian Rupnow

  2. #32
    Join Date
    Mar 2008
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    Barrie, Ontario, Canada
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    And now we reach the end. The cylinder head is flipped over and mounted in the chuck on my rotary table. It is centered under the quill, and I have a piece of 3/8" round stock turned to 11/32" on one end. I dial in the appropriate offsets as per the drawing, and YES--- the end of the rod fits into both previously reamed holes, simply by moving in the X axis on my mill. I put in a 3/8" endmill to cut the very slight counterbores at each reamed valve cage hole, then dial in the position of the slot which exposes the tip of the sparkplug and mill it 1/2" deep. Then the cylinder head is removed from the rotary table, taken out to my main garage where my bench vice lives, and I tap the sparkplug hole. Then a little clean-up, and mounted too the engine.

    Brian Rupnow

  3. #33
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    Mar 2008
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    Barrie, Ontario, Canada
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    The port holes which get drilled into the head will not be done until after the valve cages have been made and installed into the head. Then the cylinder head and the hole in the side of the valve cage are both drilled at the same time.
    Brian Rupnow

  4. #34
    Join Date
    Dec 2018
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    505

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    Brian, you make all this look so easy, !!
    Are you using the valve cages like we talked about before ??

  5. #35
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    Mar 2008
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    Barrie, Ontario, Canada
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    Yes Ringo, I always use valve cages. If you screw one up, it takes very little time to build another one. If however, you screw up a seat in the cylinder head, it's a lot of work to make another cylinder head. Besides, I build my cylinder heads from aluminum, and you can't seat a valve in aluminum.--Well, maybe you can, but it won't last long.
    Brian Rupnow

  6. #36
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    Mar 2008
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    Barrie, Ontario, Canada
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    I have a stick of 7/8" bronze that I bought a while ago. I don't know exactly what composition of bronze it is, but it's nasty stuff to machine. However, it did work quite well for an oil filler cap. You can't see it, but on the 3/8"-16 threaded shank there is a cavity .030" deep for a 1/16" cross section o-ring to prevent oil from leaking out. Also, my $20 mitre gears came today, and they look quite good. The bore on the smaller gear looks a bit too small to me, so I may open it out to 5/16" diameter.
    Brian Rupnow

  7. #37
    Join Date
    Mar 2008
    Location
    Barrie, Ontario, Canada
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    Whenever I buy bevel or mitre gears, they are never supplied with the dimensional data on how to set them up for a proper mesh. I can figure it out using the center finder and read-outs on my milling machine, but I always have to make a test block and put the holes for stub shafts in the right position to really confirm my numbers.
    Brian Rupnow

  8. #38
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    Mar 2008
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    Barrie, Ontario, Canada
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    Sometimes ya just don't know--how big things are going to be until you have them "in hand". My bevel gears came yesterday from somewhere in China. They look great, they are well made---but--They look too big to really please me. They are big enough that I think they overshadow the engine. Of course this doesn't show up until you have modelled them and put them into the overall assembly. Now I have to decide whether I go ahead and use them, (they are 20 and 40 teeth) or reorder the next smaller set which are 15 and 30 teeth. I still have to make valve cages, valves, piston, con rod, a crankshaft, and a carburetor. And I'm scheduled for cataract surgery on 15th of July and again on the 29th of July. The gears are not expensive at only around $20 for the set. This shows the current gears that came yesterday. I have decided while typing this that I will go ahead and order the smaller gear set. Time is not supposed to be critical on this engine, and I think it may look better with a smaller gear set.
    Brian Rupnow

  9. #39
    Join Date
    Apr 2009
    Location
    Ashburton, near Christchurch New Zealand
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    Perhaps the gears do look big Brian but they need to be at least the minimum size to provide clearance for the governor fly weights etc.

  10. #40
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    Mar 2008
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    Barrie, Ontario, Canada
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    I may try something different here, and actually buy a set of two cast iron piston rings. My previous attempts to make my own have not been successful, so will try a purchased set. However, my Google-foo isn't working very well this morning. Can somebody please recommend a supplier of 1" piston rings in North America. I am ready to make a piston now, but if I do buy a set of rings for it I would much prefer to cut the ring grooves while the piston is set up for turning the outer diameter.---Brian
    Last edited by brian Rupnow; 06-30-2019 at 08:58 AM.
    Brian Rupnow

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