Fox 35 50th Anniversary Break-in?

I picked up a brand-spanking new Fox 35 50th anniversary edition engine. It's never been run, so I need to break it in. Aside from the hemi head, may I safely assume that the rest of the internals are standard Fox 35 and break it in accordingly? I have a gallon of 5/29, but still need a test stand...

Also, how much power will the Fox muffler rob from this engine?

Kim Elmore (CL retread)

LAST EDITED ON Oct-08-04 AT 03:17 PM (CDT)
 
Hi kim,
The 5%-29% should be great. Big Art Adamisin recomended a 10-3 1/2 Top Flie prop for break in. IIRC, George Aldrich recomended a 9" prop to start with.
I believe you should use less than a 10-6 to allow a little less load on it. Otherwise break it in like any other iron piston/steel sleeve engine.
You do get some power loss from the muffler, but I believe it will just depend on what set up (plane, etc.,) you will be using it in as to how much it will affect performance.
There are several others here (Bigiron in particular, and others) that can give you their method.
As to a test stand, I get a 3/4X6X36 inch of oak from the local Home Supply store and cut out for the engine with a jig saw. I have some large welder's "C" clamps that I mount the board with, usually to the picnic table.
Bill <><

The 5-29 fuel is good. I use a 10 X 6 Master Airscrew prop, cut down to an 8 1/2 diameter and rebalanced for break in. The 50th anniversary series of engine is put together at the factory a little looser than previous series 35s, so it will not require as much breakin as the earlier models but will still need some. Start off with a SLOBBERING rich run. So rich that it may require the battery to remain connected to keep running. That will flush out any small particles left in the engine from manufacture and assembly. Two 2 to 3 minute runs that rich and then lean it out to a good solid four setting and run several three to four minute tanks at that setting then listen to the engine as it runs out of fuel and see if it tends to seize or grab when it leans out and quits. If it does, more solid four cycle runs are needed. if not, several runs at a hard four that is almost breaking into a two is required and then put it on a plane and fly it.

I haven't noticed an excessive amount of power loss with the stock muffler, but there IS some and so a good tongue muffler will be better. Our forum host Len Neumann has and sells these.

You mentioned that it might have a Hemi Head--- Does it also have the stuffer backplate? Which Hemi-Head does it have? the Blue Magic, L&J Slant plug, or the Fox button style?

Bigiron

As for which hemi head (assuming it has one), ummmm, ahhhh... Beats me. the head *is* different form the stock head: it's got a much nicer finish and uses allen-head screws. How might I tell which head it is? As for the backplate, I plead ignorance. I've never seen a stuffer back playte, though I have read about them. It looks stock.

Remember, I've been out of circulation for nearly 30 *years.* A lot has changed since then and a fair bit of what little I knew has been forgotten!

Now, where was I?

Oh, yeah. Cheers!

Kim

The stuffer backplate is a machined plate and will be either plain aluminun in color or dark grey or black. It definitely will not look stock. The head is slightly harder to tell if it is a hemi. The factory started to gussey-up the stock heads with the 50th anniversary edition. Looking down on the top of the head at the flat area where the glow plug screws in, does it appear that there is a small crease around the flat ares at the plug base out where the fins start, (about 1/2 inch dia at the plug)? That would be where the top of the head button would be protruding up through the head clamp ring.
As you describe it, I think that you probably have the stock head.

Bigiron

It probably wouldn't hurt to remove the backplate and check for junk in the case. Maybe even flush the engine out BEFORE you run it!
I would never think of runnung the thing slobbering rich to flush machining residue...

Since the head is fitted with socket head screws, it's a simple matter to remove it to check the hemi-head's identity.

Start slow, take your time and good luck!

LAST EDITED ON Oct-09-04 AT 10:46 AM (CDT)
 
I'll pull the head off to look and also the back plate to flush it out. The head has a machined-out center area about 0.5" in diameter, where the plug goes. The deck of that area is machined down perhaps .05" from the very bottom of the cooling fins. Except for the head, the overall finish of the engine looks similar to any oher Fox 35.

Cheers,

Kim

P.S.: I once had an Enya 35, and the finish on that engine was superb. It came with two heads,(high and low compression) and three venturies. Dunno what happened to it...

It's a standard head. How much difference does a hemi head make?

I'm with Big Art re props. I like the 10-3.5, since it does not load the engine, and also give you some flywheel effect to assist starting new, often balky, engines.

The little power lost due to the muffler is easily made up by running 10% to 12.5 % nitro and 29% castor. After engine has been run in of course.