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General control line discussion => Open Forum => Topic started by: Ara Dedekian on March 01, 2021, 08:58:44 AM
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Dug this Fox engine out of some forgotten stuff. It appeared to be in good condition so I cleaned it up and ran it, as is, on a prime. Looking at the front housing I assumed (hoped) it had roller bearings but its bushed with a rather thin bronze bearing. Would this be an econo 35 Combat engine from the late sixties?
Ara
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I think that's a 63/64 35x combat engine with a sport 36(early 70's) head on it.
Tom
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Early 60's Fox Rocket 35 with a 36 head.
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It probably has the roller bearings but they would be in the rear.
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It probably has the roller bearings but they would be in the rear.
Thanks for all the replies.
I didn't take it apart so I couldn't see what was behind the crank flange. I'll look again.
Ara
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Hello I have a Fox 36 the other way round a 36 Sport/slow combat engine with 35X head for raised compression, runs well on a vintage combat plane.
Regards Gerald
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https://www.rcgroups.com/forums/showthread.php?1402733-Vintage-Glow-Engines/page47#post18176405
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https://www.rcgroups.com/forums/showthread.php?1402733-Vintage-Glow-Engines/page47#post18176405
I ended up tearing it down after receiving all the above info. Steve was right, my engine has a single rear bearing. So the selectively plated crank, the single rear roller bearing and the front stiffening webs show it's a 1962/1963 Fox 35x sport/combat motor, version II as per the P.G.F. Chinn review. I found a couple of stock heads whose combustion chamber measurements and shape matched the Fox 36 head.
Ara
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Mystery solved!
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https://www.rcgroups.com/forums/showthread.php?1402733-Vintage-Glow-Engines/page47#post18176405
A follow up:
I went back into the box of rusted, dismembered and discarded engines and was able to build a working (test stand) example of the early version of the 35X Blue Ribbon Special. This is the one illustrated in the above Fox magazine ad with two roller bearings and no stiffening webs. Also found was a partial model of the predecessor of the 35X, the split case Fox Rocket 35.
Ara
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Anyone know the difference between the split case Rocket 35 and the 35X? Other than the obvious...lol
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I think the engine you are referring to is known officially as the FOX 35 Series III Combat Special. These first appeared in 1960, and again in 1961 with both these sporting the Rocket emblem on the bypass, and both had detachable front housings. The last (1962) Series III CS was the final one in that series with bolt-on front end, but did not have the Rocket emblem. The first FOX engine to have both the detachable front as well as the Rocket emblem was the 1960 29X. There were 3 FOX Rocket 35's (1959 - 1960) but all of these were plain bearing with non-detachable front housings, and all 3 had red heads. The first variant of the 35X "Blue Ribbon" followed on from the last of the Series III CS's.
http://sceptreflight.com/Model%20Engine%20Tests/Fox%2035%20Combat%20Special.html
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This is a fun thread. These Fox motors are part of our own history and they are still kickin'. The '61 CS as well as many Fox motors had a sensitive crankshaft when pressed hard with the nitro.
PS Don't forget the Rocket .40
PPS I need a crank for a 1956 .29R AKA 'The Bathtub' TS
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Did someone mention Combat Specials ?
https://www.rcgroups.com/forums/showthread.php?1402733-Vintage-Glow-Engines/page738#post30107089
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Now that I know more about the lineage of early Fox engines I went through my refurbished stuff to see what else was there. I couldn't believe what I found! (Us old guys get forgetful)
Two more split case 35's; one on the Nemesis II with the Rocket logo and the other against the leading edge. From right to left, three more 35 Blue Ribbons, early and late versions, two 35x RC's, and a bushed .29 RC. Except for the two obvious ones, all work. The Nemesis/35 was flown this past Fall.
Ara
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Interesting engine on the L.H. end - the raised head and the capacity numbers machined off, signify it's a 40. The American Model Engine Encyclopedia does not list any FOX 40 with the 4A triple jet carb - possibly a 40 sized "Special" made on either the 1965 36X BB, the 1970 36X R/C or the 1971 36X Profile Carrier Special ? Only the last 2 are listed as being available with the 4A carb. Does it have a divider (or web) in the exhaust stack ? If not, it's probably the '65 36X BB blown out to 40 size.
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Interesting engine on the L.H. end - the raised head and the capacity numbers machined off, signify it's a 40. The American Model Engine Encyclopedia does not list any FOX 40 with the 4A triple jet carb - possibly a 40 sized "Special" made on either the 1965 36X BB, the 1970 36X R/C or the 1971 36X Profile Carrier Special ? Only the last 2 are listed as being available with the 4A carb. Does it have a divider (or web) in the exhaust stack ? If not, it's probably the '65 36X BB blown out to 40 size.
Bob
Here's some photos. The case is actually spotfaced with a '29' stamped in. I measured TDC and BDC from the cylinder top. Not sure if that's how it's done for computing volume. The cylinder flange is ~.150" thick. The crank is sleeved in the front, haven't checked the rear. This engine was in a Goldberg Buster with the throttle wired open when I received it.
Hope this helps.
Ara
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More photos
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Hello
I believe the 29X RC is really a 36XRC as the bore is to large for a 29 and they share the same stroke. It is normally possible to look in the exhaust and tell a 29 from a 35 or 36 by the much thicker cylinder liner.
Regards Gerald
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That sure looks like a .40 sleeve. Expect anything with a Fox! Lots of interchangeability.
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C.T., Bob, Gerald
Your eagle eyed observations were correct. I remeasured and the volume computes to .39762 cu in. IT'S A .40! But it seems to be a modification with parts that don't fit; the bottom end of the rod rubs against the case. Hard to imagine it came from the factory with those parts. But, the engine seems to have a good amount of run time on it, the sleeve shows a lot of caked on residue. It'll have to go back on the test stand to see what's going on.
Ara
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C.T., Bob, Gerald
Your eagle eyed observations were correct. I remeasured and the volume computes to .39762 cu in. IT'S A .40! But it seems to be a modification with parts that don't fit; the bottom end of the rod rubs against the case. Hard to imagine it came from the factory with those parts. But, the engine seems to have a good amount of run time on it, the sleeve shows a lot of caked on residue. It'll have to go back on the test stand to see what's going on.
Ara
That rod looks like it is in backwards to me.
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That rod looks like it is in backwards to me.
I also noticed that but there's a step on the crank pin that mates into a recess on the back side of the rod, so it's in correctly.
The connecting rod was stuck to the side of the wrist pin from dried oil and couldn't center itself which might have caused the galling.
I freed everything up, reassembled it as I found it and gave it a quick run up on the test stand. It worked! But the mystery of what this is, 40 innards in a 29 marked case, remains.
Ara
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Well, it might be a 40 now, but at least the "29" stamped on the spotface tells us that the engine started out as a 1970 29X R/C, which did come with the triple jet 4A carb.