JPMacG

My Feedback: (2)

Thanks FDF. I was wondering about that myself.

aspeed

A plug tap with the tip ground off is pretty good for a bottomed hole. Go in twice and remove the chips to make sure everything is clean and at the bottom. Even a bottoming tap can be used on it's own if it is only aluminum or plastic being tapped. Don't forget about helicoils for the stripped muffler holes. It is an upgrade from a raw hole. I am pretty sure I have made millions of holes. Whew, am I tired, and tired again.(retired)

earlwb

A helicoil may not work in all cases. It needs the hole to be drilled out larger than one might be able to and still have metal left for it.

One technique I like to do is alternate metric and SAE threaded screws. You will notice that if you stripped a SAE threaded hole, that the next size up is a metric size screw thread. The next SAE thread size is too large of a size jump. So you can alternate SAE to metric and vice versa. That may let you rethread a hole without the hole getting too large.

Also sometimes you can drill the hole out, and thread it for a solid metal aluminum insert. Then you drill and tap the insert to fit it back on the engine. This is a technique used to move the holes apart more. You use permanent thread locker adhesive on the insert. But you do need some material there to allow you to drill it oversize for the insert though.

Here is an example of putting in a insert and then redrilling the holes farther apart more.

Cougar429

My Feedback: (3)

Sorry to take so long to reply. Yes, the tank is moved closer to the balance point simply to counter what is already a nose heavy condition, something these G/P "Replicas" were known for. A full tank would make slow speed work difficult.

Intend to take it flying later today. Hope it goes better than last time.

1QwkSport2.5r

That's what I figured. I think for having the tank moved to balance the plane, I'd keep the stock carb if it throttles nicely. I'd add a Cline regulator and a checkvalve and set it up to use a demand regulator instead of a pressure regulator as is what's included in the Perry pump. Basically a demand regulator is what is incorporated into nearly every Walbro carb in existence for gasoline engines. You could have the tank hanging a foot below the plane and the engine would still run normal..

Anyway, good luck whichever way you go.

Cougar429

My Feedback: (3)

I ran it up a few days ago and finally got the carb reasonably dialed in. Idles reliably and transitions relatively well. Mind you, things may be different in the air. It does still load up a bit mid-throttle and not sure how to set that on a Perry pump carb.

Only problem is this one has small wheels and the wife wants the new grass to go to seed, so was quite the mess I had to clean off the plane once ready to head back in. When she got home asked what I was up to. Had to come up with making crop circles in the lawn

That's the other surprise. If memory serves that tank is only 10 oz and it ran many an idle to full power cycles till it finally emptied at what I estimate was close to 15 mins!

1QwkSport2.5r

That rich midrange is going to cause a deadstick on approach to land I bet... I tried in vain to get a VP30 to work with a stock carb with no good outcome other than putting the pump in the drawer and not using it again. A pump carb (Perry) has no midrange adjustment which I think should be a mandatory feature to have. I haven't used a Perry pump carb, but I have used a normal Perry carb with o.k. Results (on a Fox B-frame engine no less). Not as responsive as a SuperTigre carb which would be my first choice for using with a pump since is has a midrange adjustment.

hsukaria

The Cline would be the same setup as the Walbro except the Cline pressurized the fuel tank with the check valve whereas the Walbro sucks the fuel out of the tank and therefore the tank is at or below atmospheric pressure. I personally like the Walbro approach more since I would not have to worry about the fuel tank/system being pressurized and possibly busting a leak. Just my preference.

1QwkSport2.5r

What I was getting at is the regulator is a fuel demand regulator, not a fuel pressure regulator. I understand the cline pressurizes the tank and that being the only difference between it and a Walbro type pump/regulator unit. The concept is the same. The Perry pump has a pressure regulator built in which can be adjusted, but the volume is higher which results in a richer midrange and idle mixture. The cline offers a much cleaner installation IMO.

1QwkSport2.5r

I think the Perry pump is bulky and though it does function, it's kind of designed for a pump carb and not a stock carb. Someday I may try it again with a Perry pumper carb. Below is a pic of a normal plumbing install and also one where I used a return line to bleed off excess volume. The return line helped, but wasn't a cure.


Sorry the second pic is fuzzy. If you look at the first pic, you can see the pump's pressure adjustment screw is backed out quite far - almost falling out. Engine pictured is a TT .46 Pro.

Cougar429

My Feedback: (3)

Well, no success. Plane would get to peak speed just below what I needed for takeoff and I ran out of room. Tried a Graupner 11/7.5 and even though I was able to get light on the wheels same result. Grass is just too long.

To confirm I had the same issue with the 52 powered Bobcat. These planes need really short grass, larger wheels or asphalt.

Did get the Harvard up so at least had some fun.

Part of the problem is the farmer decided to plant over a good portion of our field when we weren't looking and without permission, (regular tender moved away this summer so we are on our own).

Duncman

I have 2 early 50's Fox .35's, both excellent condition. Plan to scratch build a Ringmaster this winter for one of them. just a nostalgic moment.

Hobbsy

My Feedback: (102)

I pulled my 2nd oldest Fox 74 out of moth balls yesterday, it is a ringed version and has been stored wtih Corrosion X for a couple of years. I think I broke every Fox rule but it did fine. It's going on to a Hangar 9 Alpha 60. It is new enough to have the CNC ports. I used a newer big combustion chamber head button and a single shim/gasket.

Engine===Fox.74 ringed
Prop=====Bolly 13.5x6
Fuel=====Wildcat 10% 2/2 18% synthetic
Plug=====Fox idle bar
Muffler===Fox Quiet muffler
After 30 minutes at various rpm
Max rpm==10,460
Idle=======2,000 rpm very smooth and very quiet.

1QwkSport2.5r

Why the name change?

Hobbsy

My Feedback: (102)

No particular reason, I signed off and then came back as a non moderator and will only post on RC engines subjects and the occasional airplane or radio set up. That's it. The old .74 runs pretty good doesn't it?

1QwkSport2.5r

Gave up the Mod status then?

Given its age, yeah it doesn't run too bad. It turns about the same rpm my Old K&B .65 drone engine runs...

Hobbsy

My Feedback: (102)

I think after a while I'm going to compare it to my Irvine Q-72. The Fox .74 sits in the exact same holes as the Saito .80 I removed from the Alpha .60.

1QwkSport2.5r

Nice! I kinda lost a lot of faith in Fox after dealing with a few problem examples... Though I have to keep in mind they were bought second hand and without any provenance, it's a crapshoot if you're getting a molested example.

I'm pulling the MDS P/L out of the .50 carcass and cutting some shims for the .50 liner I got from you to get it ready for dieselizing. We milled the crankcase to square it up and drop the MDS liner for appropriate timing. Shimming the liner up .020" puts it at factory height, but I might raise it only .015" which should drop the timing a touch and maybe make it a bit torquier. Making some diesel fuel up later this week. I'm wondering if a Perry carb will be (.270" choke) precise enough or if I should put a 2-needle carb on it. I have an adapter from Conley.

Hobbsy

My Feedback: (102)

You may have to grind the hump off of the back of the Perry to get it to sit straight up.

I can pretty much guarantee you the the Fox .74 is at least 1,000 rpm stronger the the anemic .65 Sportster

1QwkSport2.5r

I didn't have to on the carb I have. It fit just well enough to barely clear. I don't recall if I slightly elongated the holes in the adapter or not.

Hobbsy

My Feedback: (102)

I was looking through some Fox boxes and found treasure, I found a real Fox .50 and a .46 that I converted to a .50 and an MVVS 49 quiet muffler. I also took the time to make the little bushing to move the throttle lever out away from the engine, they're too close to suit me. It does not appear to be wearing a stock prop driver.I got the camera a little too close and washed out the 50 stamp.

hsukaria

That MVVS quiet muffler is similar to the larger one I have for my Fox 74. The second chamber is just a simple can that is riveted to the main one-piece muffler. Some time after use, the second chamber (the simple can) came loose. So now it is a singe chamber muffler. A bit louder, but still same performance and is very lgithweight, as light as the stock Fox regular muffler. Performance is about the same as the Fox regular muffler also.

I am finally getting my hands on a Fox Quiet muffler. I purchased it with a Fox small-case engine. That will be my third c-case 40 for me. Now I have to find some airplanes for them. What airplanes do y'all recommend for the Fox 40 c-case? The Fox 40s I have are using a stock Fox muffler, a Fox Quiet muffler, and a MACs one-piece muffler. I think 2 of them are the MkX carbs, and one is an EZ carb.

Duncman

If I was smart I'd do the same thing.

Charley

My Feedback: (2)

Great find! That looks like an air bleed carb. I have two Fox .50's, both with MK X carbs. Noisy as H--l but run great.

CR

1QwkSport2.5r

My .50 came with an MkX C I believe, .330" choke. My 46 ABC came with an EZ adjust carb with the same .330" choke. I swapped and put the EZ carb on the .50 when we ran it on diesel and it ran and throttled okay considering the cylinder was shot. I put the Perry on the .50 recently because we fitted a MDS .40 cylinder and piston into it and found the Fox EZ carb was just too big for the smaller .42 displacement and modest port timing. We drilled the piston to fit the Fox rod and wristpin. Best we could get out of the MDS/Fox hybrid (dubbed Frankenfox) was 12,800rpm on a 10x6 APC and 10% nitro. I think there is lots of room for improvement with the FrankenFox but I first need to get a head button machined to fit the MDS liner. But that's for a different decade as my machinist friend is moving back to Texas.

I'll be picking up some John Deere starting fluid tomorrow so I'll be one step closer to dieselizing my .50 again.