fujiman

My Feedback: (133)

what i do is remove the plug and spin the eng. over until ALL oil is expelled and no more vapor comes out the plug hole. never had a plug destroyed doing it that way.

fujiman

My Feedback: (133)

some fuels contain silicon in the mix and i remember clearance lee speak of this and the element gets coated with a glass like stuff that lets the element glow but won't ignite the fuel mix. i've had this happen to me too. new plug problem goes away at least for a little while!!!!!!

computermonkey

My Feedback: (90)

fujiman PM sent about adapters

fujiman

My Feedback: (133)

check your e-mail, i returned a reply.

computermonkey

My Feedback: (90)

must be RCU, I'll probably get it in a little while

hsukaria

About 2/3 of my engines are mounted inverted or near-inverted. So, I can see that I have to start this new ritual at the beginning of flying season or after long storage.

Scirocco14

HI all,

I'm nearly at my wits end, and hope someone here can help. I have an Ultrasport 40 with a Fox 40 Deluxe engine on it, the small frame one with the square carb boss/mounting. Here's my problem: it idles fine and I seem to have the mixture close using the pinch test and holding the airplane nose up while running. The top end is fine too, not too rich and not too lean based on tach settings (just out of 4-stroke and well below peak RPM). In the air it unloads a little bit and the top end doesn't seem to change much doing big loops and vertical uplines.

But the MID-RANGEis driving me nuts! When I go to full throttle from low or mid throttle it hesitates, burbles, sputters, clears its throat and then goes back to normal. No matter what I seem to do helps. If I lean the bottom end, it won't idle and dies when I do the pinch test. If I lean the top-end, it starts "frying eggs" in the air and goes too lean.

Am I missing something? Is there a needle mod I can do to help lean the mid-range a little bit? I don't mind experimenting but would like to pick the brains of the local experts first.

The engine is mounted sideways ( 90º ) and has a short extension on the muffler to clear the bottom of the fuselage. See pic below. Tank is in stock location on the Ultrasport, almost perfectly in line with the carb.

The plane flies so nicely with this engine (at full throttle) and I'd hate to change it out.

Thanks!

fiery

My Feedback: (2)

Sound like the taper on the end of the idle needle is too blunt. Re-profiling is required.

hsukaria

Nice plane Scirocco.

I am no expert, but I would try a hotter plug just out of desperation.

Also, how much nitro are you running? I have a SuperTigre G51 that was doing exactly the same thing you describe. When I switched from 15% nitro to 5% nitro (with minor tuning the HSN), it fixed the problem completely.

Scirocco14

Thanks for the compliment. Ido like how it flies!

I'm running about 8% nitro; I use Wildcat 10% nitro and add 6-8 ozs of castor per gallon which reduces the nitro %.

I did find this page, does anyone have any experiences with the mods mentioned?

www.fayettevillercclub.com/id59.html

Thanks!

Mark

earlwb

I don't remember seeing a Fox engine with that anti-oiling slot, but I haven't looked at the small frame .40's in that area yet. I haven't had to replace the bearings on a .40 engine yet, so I haven't had a reason to notice yet.
Now other brand engines have used it and it can be a problem. So carefully filling in the slot does work on those engines that have it.


Fine tuning the needle profiles:

Cougar429

My Feedback: (3)

O/K. I need some more experienced motor heads to answer some questions if possible. I grabbed these two in a bulk buy at a swap meet recently and have no ideas of their genealogy. Obviously both are pre-schneurle and I'm making a guess straight C/L.

The one with the silver barrel and no glow plug has "Fox 29" stamped on the left side of the barrel with a three screw back cover. Wonder what age this could be.

Second motor only has "35" embossed in the LH case wall and has a removable barrel assembly and head. Three long screws fit through the head and barrel into the main case while the remaining 3 are shorter and only tighten the head to the barrel. This one has a four-bolt rear cover and a rather odd prop drive flange with what appear to be half moon protrusions in place of the more common straight or helical cut notches. I wonder if this is also a Fox motor and, if so, what year. The barrel/casing seals with a composite gasket which is also the case with the head, (in comparison the soft alloy I'm used to).

After cleaning them up both have very good compression.

proptop

My Feedback: (8)

The engine on the left is a McCoy...probably from sometime in the early to mid 60's? My guess on the Fox .29 would be '70's era? I have a Fox .35 that I bought new in the mid 70's that looks like your .29

Cougar429

My Feedback: (3)

Thanks for the info. I forgot to mention the 35 had a red head, but the paint came off as a result of a glycol soak. Anyone have a recommendation on a replacement paint? Wonder why the name is not evident on the casting as it is in any pic I find online.

Also, although I know this is not a forum for these motors, I noticed no method to prevent the pin from walking in the piston. What would prevent it from eating the bore wall?

earlwb

There is nothing to prevent it from moving out and possibly touching the cylinder walls. But apparently it doesn't happen. As for the paint, it looks thick and makes me think it was thinly powercoated. The paint tends to discolor easily and chip and come off more quickly anyway. So I don't think they did anything fancy for paint, they just used something cheap. But the old Ford high temperature red paint is a exact match though.

http://www.airplanesandrockets.com/m...ccoy-35-cl.htm

proptop

My Feedback: (8)

About the wrist pin...IIRC, I think there are (or are supposed to be ) Brass wear pads that look like eyelets, pushed into the pin holes?

Might be a different engine that I'm thinking of, but there should be some sort of wear button, or something in there to keep the pin from rubbing the cyl. walls. It's been quite a while since I've had my McCoy red head .35 apart...but seems to me I saw what looked like Brass eyelets. You should be able to find something similar to fit?

I was gonna mention something about the missing red paint...the anti-freeze removes paint rather well too, doesn't it?

earlwb

The McCoy .35 engines may have had brass tips or nylon or teflon tips on the wrist pin. But in the exploded parts view of the link I posted above, it doesn't show any though. Although it could be simply considered part of the wrist pin at the time.  I don't remember having seen any pads on the engines from my youth days.

Cougar429

My Feedback: (3)

Unless epoxy based or powder coat not much survives a hot antifreeze bake. As you can see, it sure does a nice job of cleaning all the old gunk off.

hsukaria

I thought they were new until you mentioned the missing red paint.

Cougar429

My Feedback: (3)

Thanks. I have to admit on the really annoying ones I go low pressure bead blast with light material. You have to be careful as prolonged exposure can still remove alloy away from the gunk, leaving you with a raised boss. Takes a bit of a touch.

That and soft brass brushes to get into the recessed areas as some crud still sits there after the glycol bath. No longer bonded on, just stuck in the cracks.

One thing I noticed on the McCoy was the fuel inlet seems to be on the opposite side to any I find running in the vids and the parts breakdown earlwb provided. Would that also be the case on the Fox?

proptop

My Feedback: (8)

I like to have the fuel inlet on the exh. side...that way, if the engine is side mounted (like on a profile fuse. stunter, etc. ) the needle valve is pointing up. (just don't run out of fuel while inverted... BTDT )

I found a Badger mini abrasive blaster (looks like an airbrush ) at a garage sale that I can do small jobs with...works well to get that older Supertigre looking finish...I can use 240-320 or finer grit in it.

earlwb

A long time ago they used to mount the engines so the exhaust was facing upward. So having the needle valve facing up like that puts the fuel inlet on the left side of the engine. I think at the time it was to keep the exhaust from ingesting dirt, not including crashing of course.  Nowadays people mount the engine with the exhaust facing down and the needle on the left side. Or they mount the engine upright or inverted too.

Cougar429

My Feedback: (3)

The only reason I could think of was having the needle on the LH side kept your hands out of the unrestricted exhaust path. Could have been damaging, or messy to say the least.

ma_mulcahy

Hello Fox Fans!

I am considering trading in one of my old clunker engines for half off on a Fox Eagle .60 or a .74. The only concern I have is the claimed performance on the Fox .74. They say 12,700 with an 11x8. I am used to running a 12x6 at 13-14k, so this seems a bit low.

FYI, I have no experience with Fox products, so any info you can share would be helpful!

Thanks.

earlwb

Duke Fox's performance numbers are usually pretty accurate.  But you have to use a wood Top Flight prop like he used too. The wood props are more stiff and tend to load the engine more than the plastic props do. Also the stock OEM muffler is quite restrictive, so it affects performance too.  I forget what fuel he used at the time, other than it was Fox brand fuel.

After you break the engine in, it'll run good. The .74 is a strong running engine.