Author Topic: Help with what I think is a 1958 Fox .29X engine. (Read 3222 times)

frank mccune · « **on:** February 23, 2015, 03:18:53 PM »

Hello All:

I saw the post re: Fox mix up and I thought of an engine in my attic stuff.

I have what I thought was a 1958 Fox C.S. I am having doubts as to what is may be as the engine has some different characteristics from the C.S.

The engine in question has the following features:

A black head that is machined with very narrow fins and is black in colour.

A metal restrict-or in the venturi that is round with two indentations for the;e mounting of the nva.

A pressure tap in the centre of the backplate.

There is a faint circle on the left side of the engine under the word FOX that is empty.

There is no hole in the rear of the crankcase to aid in removing the wrist pin

Can a .35 cylinder be placed into the .29 case? I was once told that this was possible as the cases were the same and only the .29 liner was thicker to reduce the bore.

A soon as the temperature of the engine rises, it is a cool 15 deg.F now, I may remove the head and mike the bore.

I have had this engine for many decades and have never run it.

Any thought to what model Fox this may be?

Tia,

Frank McCune

Andrew Hathaway · « **Reply #1 on:** February 23, 2015, 03:24:46 PM »

The 29 has a milled head with more fins, almost squarish. The 35 had a cast head.
The 29 and 35 case are exactly the same, except Fox milled off the 35 on the bypass for the 29. The 35 guts will drop in the 29 case.

Are there any drilled and tapped holes in the bypass end of the exhaust stack?

Sure sounds like a 29. Is the head definitely finished black? Or is it just castor staining?

frank mccune · « **Reply #2 on:** February 24, 2015, 04:41:15 PM »

Hello Andrew:

Thanks for the great teply!

There is no hole in the exhaust stack.

This engine has a tremendous amount of compression and a perfect piston/cylinder fit! It should be very easy to start. Too bad that it may be relegated to being sport engine. Perhaps it will wind up on a CG Shoestring running a 10x4 prop for sport!

I did not pull the head to check the piston baffle as the screws may be tighter than a frog's butt. If I remember correctly, Fox head screws were always soft and the Philip slots would strip very easily.

I also have what I think is a 1961 Ball Bearing Combat Special that has the same history and also has a great p&c. Another sport engine. Lol

Stay well my friend,

Frank McCune

Andrew Hathaway · « **Reply #3 on:** February 24, 2015, 05:38:50 PM »

I asked about the drilled and tapped holes in the exhaust stack, since Fox had an RC version of the 35 with a bolt on exhaust throttle, no holes we can dismiss that possibility.

What you really want to look at for identifying a .29X is the head. If the fins are cast in, wide at the base, narrow at the top, like a 35 stunt, it's not probably not a 29X head. If the fins are uniform width from base to top, with milled grooves, it's a 29X head. Generally speaking, Fox milled off the displacement or stamped the displacement on the 29s, or milled AND stamped in the case of the 29 stunt. Just have to watch out since a 35X with the 35 milled off can be an early 36X if it has a larger gap between the head and the case, and a cast head, or it can be a 29X if it has the milled fin head. Also have to watch out for 40s masquerading as 35s since Fox liked to use stickers over the 35 marking, which fell off quickly if the engine was run.

Not sure any of the Fox combat derived engines are all that suitable for sport use. I had a Fox 36X for 20 years and thought it was a piece of garbage because I was always trying to run it rich with the venturi restrictor, on suction, with 5% nitro and a 10x6 or 9x6 prop. As soon as I pulled out all the corks, switched to a 9x6, leaned the needle etc it actually ran well. The catch is that these engines are built to run fast and that's how they want to run and run best. A 29X on a CG Shoestring would probably give a tame Foxberg racer a run for it's money.

Phil Bare · « **Reply #4 on:** February 25, 2015, 05:29:27 PM »

Quote from: frank mccune on February 23, 2015, 03:18:53 PM

Hello All:

I saw the post re: Fox mix up and I thought of an engine in my attic stuff.

I have what I thought was a 1958 Fox C.S. I am having doubts as to what is may be as the engine has some different characteristics from the C.S.

The engine in question has the following features:

A black head that is machined with very narrow fins and is black in colour.

A metal restrict-or in the venturi that is round with two indentations for the;e mounting of the nva.

A pressure tap in the centre of the backplate.

There is a faint circle on the left side of the engine under the word FOX that is empty.

There is no hole in the rear of the crankcase to aid in removing the wrist pin

Can a .35 cylinder be placed into the .29 case? I was once told that this was possible as the cases were the same and only the .29 liner was thicker to reduce the bore.

A soon as the temperature of the engine rises, it is a cool 15 deg.F now, I may remove the head and mike the bore.

I have had this engine for many decades and have never run it.

Any thought to what model Fox this may be?

Tia,

Frank McCune

Frank, What you have is, in all likelihood, a 1958 .35 CS Black head. The CS sold a lot better than the .29 X and Fox would use the .29 x prepped cases when out of the .35 CS cases. The black head is a dead give away since there was never a .29 X with a black head. The '.35' was just spot faced off the case to make it a .29 x case.

Regards, Phil Bare

frank mccune · « **Reply #5 on:** February 26, 2015, 05:20:29 AM »

Hi Phil:

Thanks so much for the reply!

At first, I thought that this engine was a a Combat Special from 1958. The fact that the engine size had been removed from the case, gave me pause. I guess the only way to settle this is to mike the bore/stroke. I will post my finding here. I hope that this engine has a metal head gasket! The old paper ones were a real pain to R&R without having to make a new gasket!

Again, thanks for the help.

Stay well my friend,

Frank McCune

frank mccune · « **Reply #6 on:** February 26, 2015, 07:08:50 AM »

Hello Andrew and Phil:

There is a Fox .29X on E Bay now with an E Bay number of 381166587938.

Was this the only model of a .29X Racing engine? It looks like an earlier Fox engine with the 4 head screws. I does appear to match the era when B Team Race was popular.

Again, thanks to both of you for the information.

Stay well my friends,

Frank McCune

frank mccune · « **Reply #7 on:** February 26, 2015, 12:05:44 PM »

Hello Phil:

Yes, I think that it is indeed a 1958 CS. I miked the bore and stroke and it came out to be .800x.700 would make it a .35. Everyting else looks like the pictures of the 58 CS that you posted.

I had originally thought that my engine was a 58 CS but now I am sure. (I think) Lol

My engine has a bridge in the exhaust of the liner and none in the crankcase. Is this correct?

Thanks for all of the help!
Stay well my friend,

Frank McCune

Andrew Hathaway · « **Reply #8 on:** February 26, 2015, 02:53:55 PM »

Hi Frank,

The Ebay engine is a Fox 29 R. There's also a later 29 R with the bath tub intake and rear needle. The first 29X was based on the 1958 CS, with a milled silver head and the 35 marking milled off the bypass. See http://sceptreflight.net/Model%20Engine%20Tests/Fox%2029X.html for the first 29X.

Gotta be careful though, because the Fox 35 RC Special looks a lot like the 35 CS and 29X, except the plug is toward the back of the chamber and it used a bolt on exhaust throttle.

35 RC Special

But then in 1962 Fox built the 29X on the series III CS case with the bolt on front end with square intake. 1965 there was a 29X ball bearing rear rotor engine, which is pretty hard to confuse with any other Fox. The 1968 29X used the 36X needle bearing case, with the 29X BB head. There are also 29s (no X) built on the 36 plain bearing sport engine, and a few of the various MK series of Combat Specials out there. Confused yet?

To add to the confusion, like Phil said Fox used early Combat Special parts to build later Rockets, and RC Special parts to built Combat Specials, and so on, so you can get combinations of features that plausibly could have come that way from Fox.

Quote from: frank mccune on February 26, 2015, 07:08:50 AM

Hello Andrew and Phil:

There is a Fox .29X on E Bay now with an E Bay number of 381166587938.

Was this the only model of a .29X Racing engine? It looks like an earlier Fox engine with the 4 head screws. I does appear to match the era when B Team Race was popular.

Again, thanks to both of you for the information.

Stay well my friends,

Frank McCune

Andrew Hathaway · « **Reply #9 on:** February 26, 2015, 02:56:31 PM »

I'd have to dig a bit deeper to see when the bar across the exhaust port showedup in the liner, but it shouldn't be there in a 1958 CS. I want to say it was a mid-60's addition, about the same time the bar showed up in the exhaust stack of the case.

Edit: Read through Bill Ives history of the Fox combat engine - http://www.clcombat.info/foxhistory.html
It mostly applies to the 35/36 engines, but also dips into the 29s and 40s. From what I've seen it's fairly accurate, with what I consider to be only a few minor errors. Between the history list, Google, and Ebay auctions, you can usually figure out what an engine probably is. Just have to keep in mind that a ton of Fox parts will physically interchange from the first stunt engines well into the combat engines, and up through the most recent stunt 35s. Between that real world ability for the parts to fit and bolt on and potentially work, and Fox's habit of using up the inventory of not exact but functional replacement parts, it can get interesting.

Quote from: frank mccune on February 26, 2015, 12:05:44 PM

Hello Phil:

   Yes, I think that it is indeed a 1958 CS. I miked the bore and stroke and it came out to be .800x.700 would make it a .35. Everyting else looks like the pictures of the 58 CS that you posted.

   I had originally thought that my engine was a 58 CS but now I am sure. (I think) Lol

   My engine has a bridge in the exhaust of the liner and none in the crankcase. Is this correct?

   Thanks for all of the help!
   Stay well my friend,

   Frank McCune

Andrew Hathaway · « **Reply #10 on:** February 26, 2015, 03:25:27 PM »

Re-the bar in the liner...

I just checked several of the engines in my stash, the first engines with the bar are the Series III Combat Specials. Interestingly, the second version Rocket 35 from the same time period doesn't have the bar. The bar is there on both the 1st and 3rd version of the Series III in my collection, it's there on the third version Rocket 35, and on the 35X I checked.

I also happen to have a 1958-ish 29X case with a liner stuffed in it. Now this is a parts engine, and it's hard to say what it is exactly, but my best guess is it's a 29X. The liner has a WIDE bar in the exhaust port. It's probably 1/8" wide vs the ~1/16" bar in the 35s.

Of course all of the above assumes that my engines haven't been messed with (much) and contain their original parts.

Author Topic: Help with what I think is a 1958 Fox .29X engine. (Read 3222 times)

frank mccune

Help with what I think is a 1958 Fox .29X engine.

Andrew Hathaway

Re: Help with what I think is a 1958 Fox .29X engine.

frank mccune

Re: Help with what I think is a 1958 Fox .29X engine.

Andrew Hathaway

Re: Help with what I think is a 1958 Fox .29X engine.

Phil Bare

Re: Help with what I think is a 1958 Fox .29X engine.

frank mccune

Re: Help with what I think is a 1958 Fox .29X engine.

frank mccune

Re: Help with what I think is a 1958 Fox .29X engine.

frank mccune

Re: Help with what I think is a 1958 Fox .29X engine.

Andrew Hathaway

Re: Help with what I think is a 1958 Fox .29X engine.

Andrew Hathaway

Re: Help with what I think is a 1958 Fox .29X engine.

Andrew Hathaway

Re: Help with what I think is a 1958 Fox .29X engine.