This has been a great Johnson engine discussion. I hope to hook up with Mr. Garcia from the other forum and get some more insight into the production operations. Thought I would post some pictures of what has been talked about here.
The NIB .35 Green Case is rare, the first production after Hi purchased the line from Orwick. You can see the lacquer flaking from the sharp edges just from box wear – imagine what happened when it was actually used!
The .32 4 bolt cylinder head would have been the next series after the green case models. Small case engines available as .29, .32, and .35 displacements.
The .29 and .32 small case engines represent the most common form of the small case series, 6 bolt heads, available as .29, .32, .33 (S), and .35 displacements. Note the displacements cast into the bypass during case manufacture.
The “S” (Stunt) is the sought after variation made by combining .29 and .35 parts to make delightful 4/2 stunt engine. Note the two examples – one has the “S” stamped into the by-pass, the other has it cast in. My theory is that Hi hand-built this variation for some greats like George Aldrich, and it worked well, so he milled the displacement markings from existing cases and stamped the “S” for early production engines. Later, cases with cast-in “S” were procured. Most of my “S” engines are stamped, not cast – perhaps there were fewer built with purpose built cases??
Moving to the large case engines, we have a NIB 29R (racing). Either not many of these have survived, or perhaps not many were made. Would love to have production records on the Johnson models!!
Next is the famed Combat Special (CS). Note the provision of both a pressure nipple and screw for plugging the backplate. I don’t know if I have ever seen a CS or an SS (Stunt Supreme) with cast-in model designations. I believe the large case engines were all built on the same case, and perhaps Hi just had the cases mass-produced without markings.
Following is the Stunt Supreme (SS). Not near the 4/2 engine as the “S”, and heavier. More plentiful on the market than the “S”.
Next is a large case 35S. I thought this might have been somebody’s concoction, but Ted Fancher told me he was pretty sure this was offered for a short time. Not the sweet 4/2 motor that the “S” was. This is the only one I have ever seen.
The NIB J/RC has the famed AM1 carburetor, quite the innovation for R/C in its day. Also note the way the venturi boss and front of the exhaust stack was milled to accept the carburetor. The R/C was shipped with the pressure nipple provision, same as the CS. The J/RC and the J/BB were the only models with ball bearings. Notice the quality of the stamping for the model designation has improved considerably – new dies??
The J/BB was the control line version of the J/RC. These seem to be fairly scarce in the market, and I believe they were produced near the end of the model airplane product years (just prior to slot cars).
The Sport Special was the last new model produced, I believe. It was an attempt to compete with the low price sport engines in the market, but was more expensive. Note that lack of any model designation on the bypass and the venturi that was short and flat – in other words, a J/RC case converted back to C/L. I have heard there are a few Sport Specials built on J/BB cases (venturi and exhaust stack not milled). Supposedly these are very scarce.
Finally, a close-up of the early NVA with the knurled knob on the end. All Johnson NVA’s are scarce – these early ones are just about non-existent. It seems the later barrel-knobbed NVA’s were used on both small case and large case engines – not sure when the cut-over was made. However, the later NVA style was sold as replacement parts for the early engines and many were replaced in the field. And, a shot of the Johnson docs offering “hop up” service for your engine. Leonard, looks like you need to lower your prices some to compete!!