QUITE A CATALOG FOR THE MACHINIST. Thlanks

Thanks Capt,n. I do all my hubs the same way. In the case of the LH threads on the Echo the stud replaces the machined threads on the crank. So from the outside everything will be the same as far as looks go. There will be no difference in the machining of the hub, threads, taper, etc. I could take one from a motor with regular RH threads and it will bolt on the one with the bored and tapped shaft with the stud.

Number 2 will be ready to go this weekend.

Flipflop nice work. What WA carb are you using? Also, looking back at the posts I can't understand what holds the bracket with the senor on the case and keeps it from moving. How do you keep the timing hub on the back of the crank?

Looks like the timing wheel just threads on...and maybe some locktite! Just a Guess. Capt.n

Are there LH threads on both ends of those cranks? Are they, threads, external on both ends?

That's an old G-23 carb that I'll use until I get another 11mm. Walbro. The sensor ring is a light press fit on the nub on the rear of the motor (that is identical to the nub on the front of the motor) It fits tight enough that I can use a drop of locktite or a tiny dab of J-B weld to make the final permanent installation. You've got to fit all of this together "dry" and check the timing to find the exact location for the pulse switch. Stock crank, LH external threads on both ends. Motor rotation will keep the timing wheel tight on the rear end (no jam nut needed) with just a drop of locktite.

flipflop: That was a very good explanation of the timing set-up you done. I may also add...a very well thought out way of doing it. I wish more people with your talent would share as much. Best Regards Capt,n

Got it now. I can't for the life of me find the other post of yours showing the parts you made for this process. Can anyone post a link??

Hi tim,

Go to lathes for conversion, post 295, click on the web site there

http://tech.flygsw.org/echo_conversion.htm Try That!

Thanks guys!!

Captin, Thanks for this website. Question: what holds the "timing sensor support" in place? Just a locktite press fit? Seems like vibration and heat/cooling would loosen it. Can you clarify? ,,,,,,,,,,,,,,, R


ORIGINAL: captinjohn

http://tech.flygsw.org/echo_conversion.htm Try That!

Antique: I just looked at the back-side of my Echo 2400engine. Around the crank seal you will see a perfect round part of the case around the seal. The O.D. is about 1.010 inch DIA. Now if the right size hole is made in sensor mounting plate...it will press on to that. A little locktite and it will stay. There is one web at top on my engine that would need to be removed. I think you will see what I mean. Capt,n

Aluminum crankcase, aluminum timing ring, even if they are different grades, I'd bet that the coefficient of thermal expansion is going to be very close. Vibration, well this is a very small part located around the C/L of the crank, any acceleration/deaccelerations are going to be very small. This little part only weighs a few grams so it's not going to take too much to hold it in place. If you were hanging a 4lb shop hammer off the rear in this fashion, then I'd share your concerns. Anyhow, mine is now attached permanently and I'm not the least bit worried about it coming off. Guess you could use one of the high temp RTVs if you are worried about the heat and vibration.

Nahhh. Loctite and a press fit is fine. For that matter the press fit would be fine too. If you ever tried to remove a prop hub from the crank you will trust the Loctite. Takes near 400 degrees of heat to break it free. Been there. Nothing near that temperature in that area. FWIW I use the 620 Loctite for hubs. Expensive but a small bottle lasts a long time. A little on the thread and a little on the crank and thats it.

Thanks for the explination, let us know how it works out. This looks like a great setup to me.

Got another winner here, sweet, smooth running little motor. Time to start saving up for a Funtana X 100 or a Jerrys Big Boy.

These are great little engines and I really like them. I presently have two flying. One in a Great Planes Fokker Triplane, and another in a Giant Scale Planes Katana 140. Both fly really well and the engines handle nicely. (I'm running both on "Gas/Glow".)

AV8TOR

av8tor1977: I bet the 2 you got flying do not have left hand threads!! Capt,n

No, they are ones I've had for a couple of years or so. My "left-handers" are waiting to be converted still. I have one that will be a normal, single, and two others now that are going to be converted into the BME twin. I will cut the left hand threads off of them, and center drill the crank for a stud as we've discussed before. I still haven't decided though if I'm going to use the two 25cc right hand thread cranks I have in the twin, for a "stroker twin".... (One of my flying 23.6cc engines is a stroker.)

AV8TOR

oldtimer2: I bet it ts getting warmer down there in the Lone Star Sate! We still have some snow here. I have been busy completly re-doing a batroom. All new inside ...and now a Jacuzzi in there. I will call you and or send a privite email. Take Care, Capt,n

Hi Captjohn,

The weather here is great now. No time to work with the hobbie, The wife has me painting the house and working in the yard every time she catches me relaxing or thinking about doing anything constructive. I got your PM, you can keep the flywheel I sent I don't need it. I still haven't managed to find a prop hub for my L/H threads to butt up to my Magneto flywheel, but no rush i guess.It sounds like you are very busy with your projects too.

Later George

Oldtimer2: I could have made the adapter, too butt up to the flywheel or the hub I cut down. The problem is I sent away for taps and they were all oversize. So I gave up. Seems like other guys doing the left hand threaded engine could make one for you. At this point I wonder just how tight there threads was. Mayby the taper and a set screw plus a lot of locktite was there answer. Best Regards Capt,n

Ok, about those left hand threads.... I rather did this for Captain John, but I think he's on vacation.

Anyway, here's some pics and instructions on a good fix.

The first one shows the crank all taped up to keep the bearings somewhat clean, chucked up and centered in the lathe, and being drilled down the factory center bore with a number 29 bit. I drilled this pilot hole as deep as I wanted the stud to eventually go, which is approximately 1.5". I ran the lathe very slow; so slow that I could almost count the revolutions, and had no problems. Just go slow, don't force the bit, and use a little cutting oil.

The second pic shows getting ready to part off the left hand threads. There are two advantages of using the factory counterbore to pilot drill the crank first. One is you don't need to use a center drill to start your new stud hole, and the other is that the left hand thread portion can be parted off easier after you've drilled the pilot hole.

The third pic shows re-checking the centering after the parting operation. The crank is now ready for drilling the hole to be threaded for a stud, right down the pilot hole drilled in the first step.

Pic four shows drilling the hole for the stud with a "I" drill. (This is for a 5/16" x 24 threaded stud)

Pic five shows tapping the hole 5/16" x 24. Be very careful to get the tap started straight, as the hole will most likely have just broken into the bottom of the key slot. It's no problem, just work carefully. (That's why I made the hole about 1.5" deep into the crank; to have good support beyond that key slot.)

And pic six shows the completed crank, ready for a stud and a normal prop adapter setup. Now when I start this engine up, I won't have any worries about the prop coming off, and I think this is an easier operation than making a custom prop hub to accomodate the left hand threads. Also, no matter how well you taped the crank up to keep it clean, I recommend a thorough cleaning, blowing out, and re-oiling of the bearings before you assemble the engine

Hope this helps someone,
AV8TOR