Posted on September 2, 2012:

       Hello folks! This episode I will be working on the valve train. I will start off with the rocker arm bracket which is made from a bronze casting as seen below. I deburred the casting with the Dremel tool before beginning work on the milling machine (not shown).

       I started off by setting up the bracket on two parallels in my milling vise.

       I used an end mill to trim the base of the bracket to about .130” thick.

       The next step is to lay out the two mounting holes on the bottom of the casting as the prints require.

       I squared up the #11 hole with my wiggler tool...

       I then used a #2 center drill to spot the hole...

       And now for the #11 drill bit...

       I lined up the second location and drilled the #30 hole at this time.

       I mounted the bracket to a 1-2-3 block so I could machine out the rocker arm pivot hole and slot. I used a little blue Locktite under the bracket to help keep it from shifting...

       I now centered up the spindle on the pivot hole location...

       I then drilled out the hole with a #38 bit straight through the bracket.

       I followed the #38 bit with a 7/64” bit and drilled it in to a depth of .230”. This will allow clearance for the pivot screw’s shoulder.

       The next step is to tap the lower portion of the bracket with a 5-40 tap.

       Next I mounted up a 3/32” thick slitting saw to cut out the slot needed for the rocker arm. I positioned the saw so that it was .095” down from the bracket’s vertical center to the bottom edge of the cutter. I then made a pass to cut out the bottom side at .530” away from the 1-2-3 block. The saw was then moved up .096” to finish off the top side of the slot (.190” wide).

       The slitting saw makes a very precise cut :0)

       The next step is to spot face the front side of the mounting holes. I used the wiggler to center the spindle on the #11 hole first.

       A 3/8” end mill was used to spot face the bracket as seen below...

       I spot faced the #30 hole with a 1/4” end mill and then deburred the sharp edges with a needle file (not shown). I then tested the 5-40 pivot bolt (screw) in it’s hole...

       The next step is to machine the rocker arm casting.

       I trimmed off the molding flash and then filed the arm before mounting it into the milling vise (not shown). I then centered up the spindle on the pivot hole as seen below...

       A #2 center drill was used to spot the pivot (not shown) followed by a 11/64” drill bit as seen below...

       I followed the drill bit with a 3/16” chucking reamer to finish off the hole.

       I used an end mill to remove about .036” from each side of the arm to achieve a total thickness of .186”.

       I remounted the arm and then centered up the spindle on the valve adjustment screw hole so I could drill out a #29 hole. This hole is 1.125” on center from the center of the pivot hole. Once the hole was drilled it was tapped with a 8-32 tap (not shown).

       I now cleaned up both the rocker arm and bracket with a fine wire wheel and then polished them in the tumbler as I had with the connecting rod (not shown).

       The next step is to machine the rocker arm bushing. The bushing is made from a piece of 3/16” steel rod which is included in the Red Wing materials kit.

       First I bored the rod with an 1/8” drill bit to a depth of .250”...

       I positioned my parting tool to .188” back from the end of the rod and made a partial cut into the rod. I then used a needle file to deburr the edges of the bushing before finishing off the cut to remove the bushing from the rod (not shown).

       I installed the 8-32 adjustment “bolt” and lock nut at this point. I also test fit the bushing to make sure it fits into the arm as well as the bracket.

       And now for the final fit. I mounted the assembly and then fine tuned the height of the bushing so that the rocker arm would fit snug in the bracket once the pivot screw was tightened. I then filed the valve end of the arm to a slight angle so that it pushes more squarely on the valve stem (not shown).

       The next step is to get into the governor arm bracket...

       I mounted the bracket in my three-jaw chuck using some parallels to square it to the face of the chuck (not shown). I then used a 15/32” drill bit to bore a hole in the center of the casting as seen below...

       I used my boring bar to widen the hole to 1/2” diameter.

       I now removed the raised portion of the casting with the boring bar so that it is flush with the lower face of the casting as seen below. I widened the face to extend into the bracket tabs at a diameter of .890” to make clearance for the shift collar.

       I decided to use my 1/2” tuning arbor to machine the back side of the bracket. This will keep the next few steps concentric to the bore of the bracket.

       I turned down the OD of the bracket to 1.162” which will match the OD of the hub on the flywheel. I also faced the back side of the governor tabs at this point.

       I trimmed down the thickness of the bracket’s base to about .180”. Note: I had to stop the cut so that I did not cut into the bushing of the turning arbor...

       I now trimmed off the last of the material on my belt sander...

       Please join me again on the next episode of the Red Wing project where I hope to finish a few more of the smaller parts of the engine.

Thanks for reading and see you next time!!!

Don R. Giandomenico

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