Lou Crane

R.O,
I don't think the .78s were ever offered with more "modern" carbs, so the old Duke Fox carbs' method may work for you. (The old Fox carbs had a 'throttle plate' not a drilled hole that matched body and rotor at WOT.)

He got mixture regulation by the rotation of the needle thread into the fuel needle outlet. The low speed needle moves with the throttle arm. So, he recommended setting the idle/low throttle first. When the idle setting barely keeps the engine running, THEN work on the high speed. (He faced the fact that production tolerances might occasionally require 'touching up' the sector on the throttle plate where air was closed off. There should be some of his "Duke's Mix' columns on this on the 'net.)

Instead of the modern "high pitch cam" to close down the fuel metering for lower RPM, he used the thread pitch of the low speed needle to set idle. Crude in a way, and sophisticated in a way - but effective.

Sideways motion of the throttle on modern engines looks like over 1/16"; he used a sideways travel of about 1/50th of an inch.

Luck! Hope this helps. Remember, particularly for lapped piston/sleeve "iron" engines, that plenty of castor oil in the fuel is VERY helpful;l

Charley

My Feedback: (2)

I have seen photos of the c.1981 Fox .78 with the twin-neeedle carb that most of us are familiar with.

CR

hsukaria

Might be a retrofit to the newer carb. Which might also be a possibility with this particular engine. A picture of the actual carb would settle that question.

Charley

My Feedback: (2)

It came that way. Look through here: https://www.google.com/search?q=hist...hrome&ie=UTF-8

CR

R. Ortiz

Thanks for your prompt reply Charley. Here are some pictures of the carburetor. They are not very good but I hope that they will be of help.

1QwkSport2.5r

Sure looks like an MkX carb to me. Set it like any two needle carb and it should work good for you.

hsukaria

yep

R. Ortiz

Hi Charley. Did you get the pictures that I sent you?

Lou Crane

R.O....

The main difference between the 'traditional' Fox carb and the newer types is that the fuel tube is twisted by movement of the throttle arm on the older ones. In newer carbs, mostly, the fuel line connects to a non-moving nipple on the carb body.

Sure, the housing looks like newer carbs, but if throttle arm action rotates the fuel line, it may use the method I described above.

If one way doesn't work, try the other...

Luck!

Aaron L.

The last .78RC engines (1980 version with the two muffler mounting lugs on the front and back of the cylinder) were equipped with the MK-X carburetor. I have one (as well as an earlier .78 with the 2-jet carb). Mr Ortiz's .78 looks to be the late style (you can see the front muffler lug in the pic) and would have come from Fox with the MK-X carb.

1QwkSport2.5r

Yes, the .78 being discussed has the MkX carb. There is no mistaking the old butterfly carb and the MkX. *completely* different animals. FWIW - the old 2/3 needle butterfly carb's and such do not have "Fox" cast into it - only the MkX does AFAIK.

R. Ortiz

Thanks for the help guys.

Charley

My Feedback: (2)

Yup, Mk X carb. There's a pretty good writeup here: http://www.fayettevillercclub.com/id57.html

On setting the Low Spd needle it says to close the barrel so just a slit open is visible but some of the Fox manuals said to use a modeling pin as a gauge. I always used a small T-pin.

CR

F4 Phantom blue angles

Hi Guys,Im new here. I have been in this hobby since 1989.but started when I was about 12 yrs. old. I want to say I had 3 Fox engines,a .40----a .45,ringed,----and a Ealge .60. I Loved my Fox .40. When broken in it SCREAMED. I didn'like my Fox .45, It just didn' perform like my .40. My .60, Ran great if you could get to run right. Im not here to down grade DUKE, only to give my opinion, However, I think the .40 was one of the best engines out there. But all in all, I love his engines. They work well,and are priced well.

Lou Crane

Er, uhh,...

Another look at the pictures, and the large-angle groove which shifts the throttle sideways IS clearly visible. Ergo, MKX. The throttle-plate older carbs WERE more critical, because the sideways travel was much smaller. ...but, they did work well...

dm12345

hi guys. i just acquired this engine. very little use. maybe only broken in. it's very neat but i don't think i have a use for it. any interest? not %100 sure what the value is 'cause i can't find another one in the same condition. have paypal. can ship.

1QwkSport2.5r

I wouldn't expect to see more than maybe $75 for it and that's because you literally have all of most of the paperwork. You might get more from a collector for it, but they're few and far between these days. You could try a classified ad, but probably better off to take your chances and eBay it.

Hobbsy

My Feedback: (102)

The Fox Quicky 500 usually came with this pipe, it is unbelievably loud. They sold for 169 bucks in their day. Even though they had a throttle they were basically wide open only engines. The result of wild timing. If I hadn't just bought an LA 10 I'd take you up on that.

1QwkSport2.5r

The true quickee 500 racing engines were true ABC with pipe timing. There is a sport quickee such as the last posters' engine that is lapped iron/steel and they may have come ringed too. They are not timed high like the ABC engines were. Go back a few pages and you'll see another fellow with a "quickee" .45 ringed engine. Not the racing engine - just a decent sport engine.

Notice on the last poster's quickee engine box says "sport" and "lapped" on it. That's the tell-tale it's not the "hot" one.

dm12345

part # 24197 is iron/steel .40. missing the spinner dammit! i could do $75 shipped if someone wanted it.

1QwkSport2.5r

As I said, $75 for that particular engine is likely to be the top mark that it would bring. More likely, maybe $50. The market is really soft for glow engines - especially Foxes. I have a NIB .46 ABC that I would almost have to give away. I had it listed for a stupid low price even and had no bites on it and it's a much more desirable engine. Fox stuff isn't really sought after these days, so be willing to eat it if you really need to sell it or sit on it for awhile in hopes the market improves.

hsukaria

Yeah, I am saturated with enough Fox engines. I don't have any in planes right now but plan to install 2 out of the seven I own by next yaear. So I would say I am saturated with engines, Fox and glow engines in general.

1QwkSport2.5r

I have 56 engines right now. About 15 of them are in or on something currently. Putting 5-6 up for sale, and I have 4 on the bench to get modified. I have a brand new 8-port modified Novarossi in one of my RC trucks ready for breaking in - that one should be a real thumper.. I probably won't have time to fly much this season.. Maybe a little flight time on the micro T-28 if the weather behaves.

the pope

Hi there Husky , and that should stop u why ??

hsukaria

Not complaining about anything, just that I have a disproportionate number of engines to airframes and although I don't have as many engines as many guys around here, I think I have enough to last 2 lifetimes.