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Author Topic: What engine is this?  (Read 1176 times)

Offline usnscpo

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What engine is this?
« on: January 08, 2013, 10:17:57 AM »
I confess that I'm a lurker... first post.  Couple weeks ago I bought an unbuilt Brodak P40 ARF from a friend.  The deal included an engine.  At the time of purchase I thought it was a Fox .35, but on closer inspection, I'm not so sure.  There are no markings on the case.  Two distinqtions:  Square venturi (with a piece of brass pipe inserted); and 6 bolt back plate.  The engine is used, but still has very good compression.  The angle on the venturi is not an aggressive angle like I've seen on a Fox.  Its perhaps 30* if that.

Can anyone tell me what I've got?  I need a muffler for it so I can run muffler pressure.  Maybe a picture would help?
Thanks much,
Chris
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Offline Andrew Hathaway

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Re: What engine is this?
« Reply #1 on: January 08, 2013, 10:30:32 AM »
A pic would certainly help, the angled venturi and 6 bolt backplate along with a lack of markings sounds rather Fox'ish, but there are so many variants in just the Fox category it'd be hard to identify without putting eyes on it.
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Offline Phil Bare

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Re: What engine is this?
« Reply #2 on: January 08, 2013, 10:35:04 AM »
What you have sounds very much like the 1976 Fox combat special .36 MK3, but with out a pic, its hard to say.
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Offline usnscpo

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Re: What engine is this?
« Reply #3 on: January 08, 2013, 01:28:03 PM »
I'll get some pix put up.  Thx for the help, gents!
Chris
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Offline usnscpo

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Re: What engine is this?
« Reply #4 on: January 11, 2013, 04:27:33 PM »
I was bored at work today so I did some googling and found several pictures of my engine.  Its a Fox .40... there's even one on flebay right now.

Now that's done, can anyone tell me how to run this engine?  Old school 4-2-4 break?  Wet 2 cycle? 

I have a large prop selection, so I'll be able to find something to work.  Know that I'm mainly an RCer but wanting to relive my CL youth #^.  So I guess you could call me a Sport flyer for now.  Might try stunt in the future... but I have to say, carrier looks like a lot of fun.  Anyway I'm getting ahead of myself.  I've yet to log a single minute until spring arrives.

Thanks gents!
Chris
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Online Tim Wescott

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Re: What engine is this?
« Reply #5 on: January 11, 2013, 04:35:58 PM »
The venturi bolts on with a flange?

At a guess, since its Schneurle ported, I'd say a wet two cycle.  I have two of those that I got for cheap; I got as far as finding out that the one with the decent piston seal blurps fuel out the front bearing like a fountain and kinda lost interest.

It's a steel-steel or iron-steel piston/liner fit, so you want to use lots of oil, probably with a good amount of castor in there.
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AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Andrew Hathaway

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Re: What engine is this?
« Reply #6 on: January 11, 2013, 05:01:59 PM »
Keep in mind that Fox built a .29, .36, and .40 all on the same basic compact case, and they all look very similar.  Some of them are marked with the displacement, but sometimes the only way to identify the model is the subtle features.

Assuming that it's a .40, it won't like a 4-2-4 type run, a wet 2 is more appropriate with how the engine will want to run.  They aren't a really popular engine for CL stunt, and most you do see have been reworked by Lew Woolard.
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Online Tim Wescott

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Re: What engine is this?
« Reply #7 on: January 11, 2013, 05:12:41 PM »
Quote from: Andrew Hathaway on January 11, 2013, 05:01:59 PM
Keep in mind that Fox built a .29, .36, and .40 all on the same basic compact case, and they all look very similar.  Some of them are marked with the displacement, but sometimes the only way to identify the model is the subtle features.

Whoops -- at least the one I'm thinking of is the honkin' big one that's in a case that'd be more at home wrapped around a .60.

I should know better than to assume that I can identify one Fox engine out of the bazzilion or so made.

The one that looks like the one here: http://www.foxmanufacturing.com/index.php?main_page=product_info&cPath=143&products_id=285
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Phil Bare

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Re: What engine is this?
« Reply #8 on: January 11, 2013, 06:58:00 PM »
Quote from: usnscpo on January 11, 2013, 04:27:33 PM
I was bored at work today so I did some googling and found several pictures of my engine.  Its a Fox .40... there's even one on flebay right now.

Now that's done, can anyone tell me how to run this engine?  Old school 4-2-4 break?  Wet 2 cycle? 

I have a large prop selection, so I'll be able to find something to work.  Know that I'm mainly an RCer but wanting to relive my CL youth #^.  So I guess you could call me a Sport flyer for now.  Might try stunt in the future... but I have to say, carrier looks like a lot of fun.  Anyway I'm getting ahead of myself.  I've yet to log a single minute until spring arrives.

Thanks gents!
Chris

Chris, in my previous answer, I was thinking venturi cast as part of the crank case and if that is so, my first answer  is about right. If the venturi is flanged and held on with two screws, then there is a wide range of possibilities and visual media would be required.   :-)

Most of the Fox schnurele ported engines are way over compressed and timed pretty high, so a 4-2 run is not what they like so running a rich 2 cycle is about as good as you can do with a stock engine.
I have a .40 (along with serveral other schnurele ported Fox engines) and can tell you that in stock trim, FAI fuel will give you the best results. If you add a couple head gaskets, you can use 5% nitro fuel with 25% oil. Decompressing and 5% nitro gives you a broader needle. A good 11 x 4 prop seems to work about as good as anything for me.
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Offline Andrew Hathaway

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Re: What engine is this?
« Reply #9 on: January 11, 2013, 07:44:29 PM »
Quote from: Tim Wescott on January 11, 2013, 05:12:41 PM
Whoops -- at least the one I'm thinking of is the honkin' big one that's in a case that'd be more at home wrapped around a .60.

I should know better than to assume that I can identify one Fox engine out of the bazzilion or so made.

The one that looks like the one here: http://www.foxmanufacturing.com/index.php?main_page=product_info&cPath=143&products_id=285

There are two 6-bolt backplate style Fox 40s.  There's the compact style case that's the smaller/lighter case that was used on the Combat Special, and a variety of .29, .36, and .40 engines.  These have the venturi/intake cast into the case.  Then there's the larger heavy case with a similar 6-bolt backplate, and a pad for a bolt on carb or venturi.  From the square venturi description, it sounds like it's probably a compact case, since the bolt on venturi for the larger case is round, but that's just a guess.  From the brass insert it might be a converted R/C engine, but that's another guess.

What I was really getting at is that within just the compact case family there are different displacements and configurations.  They all look very similar next to each other.  Here's a few pics robbed from completed auctions on Ebay, in this case a .29, .36, and .40, the .29 and .40 are stamped on the mounting lugs if you look very closely.



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Offline usnscpo

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Re: What engine is this?
« Reply #10 on: January 11, 2013, 09:48:33 PM »
Oh Joy.  It looks just like all of those ^ right down to the prop mounting arrangement. 

I appreciate all the input.  So its likely this engine won't do a traditional 4-2 break without considerable modification.  That's fine.  I don't really care at this point.  This will be pulling my first bird in a very long time.  :-)  I'll pull the head and measure the piston diameter to confirm displacement.  Its awful strange that Fox didn't even bother with a branding mark on this series of engines.

I just noticed the Neuman's Stuka Stunt-works are nearby.  I may give them a call and pop over to see what they have available.

Thanks again all!
Chris
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Offline Phil Bare

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Re: What engine is this?
« Reply #11 on: January 12, 2013, 05:08:43 AM »
Chris, In order to make a small case Fox schnurele engine run an acceptable 4-2 run, the timing has to be changed and the compression  has to be reduced. Lew Wollard accomplises the timing change by dropping the sleeve in the cylinder which requires machine work, he also opens up the combustion chamber in the head by remaching it. Theses engines are very powerfull but pretty 'high strung' and are really not suitable for a stunt ship in stock form.If you are interested, I have a new in the box OS LA .25 that I would trade you or I also have a very nice OS .40 FP set up and ready to go for stunt. Both have mufflers.

Regards, Phil Bare
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