My Hodgson 9 Radial Final Assembly

[mayhugh1]

Success !...
I bolted the engine down to a workbench in my backyard to try for a 'second pop'. I'm currently running the oil system open loop. I am pumping fresh oil into the engine from my oil tank; but instead of allowing the scavenger pump to return the oil to the tank I am just pumping it into a waste container for disposal. I put my thumb over the carb intake and turned the prop over by hand two turns to prime it using the idle and high speed settings I came up with in my shop last night. The priming wetted my thumb with fuel and I took this to be a good sign. I opened the throttle half way and turned the ignition ON making sure the prop wasn't resting in a position with the coil current ON. I had the drill starter in my hand; but, just for the heck of it, I gave the prop a slap with my hand. I couldn't believe it. The engine started right up and ran and it sounded great. It appeared to be running on all cylinders as I could feel hot exhaust gases coming from all the exhaust pipes including #5 and #6. Even more astonishing to me was the fact that I was getting no oil smoke out of any of the exhausts. My brain was in a such a startled state that I couldn't decide what to do next. I had a notebook set up so I could record various carb and timing settings and their results as I went through what I thought was going to be a laborious process to get the engine to run. But this I wasn't ready for. I decided to use up the fuel remaining in the tank using the existing carb settings with short runs of a minute or so each and to allow the engine to cool down completely between these runs in order to help start the seating process for the rings. I only got three short runs because this engine really uses up fuel quickly. Part of this, of course, is related to the fact that I'm using methanol, but right now it seems to be using about an ounce per minute at half throttle. Because of comments I had heard from other builders I wasn't expecting the high temperatures at the heads and exhaust pipes that I'm seeing. After a minute of running, mine are much too hot to touch. Lee had told me the exhausts would be cool to the touch and so maybe when I optimize the carb settings I'll find I need to richen the carb. I spot checked the #2 plug and it looked like new, but frankly methanol isn't going to color the plug in any meaningful way.
The engine started easily by hand for all three one minute runs, and so I decided to quit and celebrate. My next step will be to optimize the carb settings for methanol/Crowne camp fuel. I plan to continue using short runs with cool down between for the first half hour or so of running. I'll also continue to run the oil system open loop for the first hour or so of running.
After I get the carb and timing settings to a point where I can't seem to make any further improvement, I'll take and post a short video before changing over to gasolene or perhaps going back to the Walbro (yeah, ... like that's going to happen). - Terry

 

[kuhncw]

Congratulations, Terry! Glad to hear your radial fired up on the first flip.

Regards,

Chuck

 

[RonC9876]

Terry: Way to go! You must have been smiling from ear to ear when it fired right up. Glad you decided on hand cranking. Less chance of doing damage. Congratulations on a job well done. Ron Colonna

 

[petertha]

...I had heard from other builders I wasn't expecting the high temperatures at the heads and exhaust pipes that I'm seeing. After a minute of running, mine are much too hot to touch.- Terry

First off... YAAAY! So glad to hear its running!

I cant speak for your exact fuel methanol mixture but it's not uncommon for typical RC 4-stroke methanol burners to be pretty hot in my experience. Some of the exhaust hardware we happily ran on 2-strokes sometimes melted or fatigued on 4-S.

Its been too many years to remember exactly, but head temps north of 400F ring a bell & exhaust headers temps higher yet (influenced by prop blowback cooling & other variables). You probably have seen these cheapy temp gauges, but they are kind of handy for checking different spots quickly.
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXEMG5&P=ML

I will be interested to see your cylinder temp variation once its broken in and up & running, Congrats!

 

[mayhugh1]

Thanks all for your congratulations. The tips that many of you gave me during the past weeks were greatly appreciated and helped me get it running.

Petertha,
Your comment on your experiences with 4-strokes running hotter head and exhaust temperatures when burning methanol instead of gasolene caught me by surprise. I thought the opposite was true. I'm not at all familiar with its chemistry, but I thought methanol had a cooling effect in the combustion chamber because of it higher heat of vaporization and that fact that almost twice as much is required to produce the same power. I figured its cooling effect was also one of the reasons it is a popular fuel in air-cooled RC engines? Do you have any references you could point me to?
I run methanol in my other two model 4-stroke engines, but I don't like it because it corrodes aluminum (you need to make the carb and fuel tank out of brass). It's expensive, and its volatility is so low you have to mix it with something more volatile in order to reliably cold start a small engine. I expect the oil or some other corrosion inhibiter in two stroke fuels limits the corrosion in (lightweight) aluminum R/C carbs. The only advantage I can see in using it for model engines is that the carb settings are less sensitive; and so the sweet-spot is maybe twice as wide as when using gasolene. I tried gasolene in the Jerry Howell carbs on my V-4 and V-twin engines when I built them and could not get a consistent combination to run.
Now I'm curious. I'm going into the shop and make a new set of needles for the carb on the V-4 to see if I can get it to run on gas. I'm going to lengthen the taper by a factor of two and see what happens. - Terry

 

[Lakc]

Congratulations, it sounds like you have it dialed pretty dead on!
Alcohol as you know has half of the heat energy of gasoline, but if you burn twice as much its just as hot as gasoline, minus the latent heat of evaporation difference. This tends to effectively lower cylinder temperatures, but more fuel beyond that leaves more leftover cooling benefits further down the exhaust valve, port, and tube. As I said, the way it looks, it seems pretty dead on.

 

[ozzie46]

Congrats on getting it to run.Thm:Thm:Thm:Thm:

When can we expect a video?? Hmmm. ;D;D;D

Ron

 

[GailInNM]

A great milestone Terry. One you can be very proud of. I have followed from the first post and very happy for you, but there was never really any doubt of the final outcome. Congratulations.
Gail in NM

 

[Niceonetidy]

What a marvelous experience to see the engine run, congratulations, well done

Kind regards

Colin

Success !...
I bolted the engine down to a workbench in my backyard to try for a 'second pop'. I'm currently running the oil system open loop. I am pumping fresh oil into the engine from my oil tank; but instead of allowing the scavenger pump to return the oil to the tank I am just pumping it into a waste container for disposal. I put my thumb over the carb intake and turned the prop over by hand two turns to prime it using the idle and high speed settings I came up with in my shop last night. The priming wetted my thumb with fuel and I took this to be a good sign. I opened the throttle half way and turned the ignition ON making sure the prop wasn't resting in a position with the coil current ON. I had the drill starter in my hand; but, just for the heck of it, I gave the prop a slap with my hand. I couldn't believe it. The engine started right up and ran and it sounded great. It appeared to be running on all cylinders as I could feel hot exhaust gases coming from all the exhaust pipes including #5 and #6. Even more astonishing to me was the fact that I was getting no oil smoke out of any of the exhausts. My brain was in a such a startled state that I couldn't decide what to do next. I had a notebook set up so I could record various carb and timing settings and their results as I went through what I thought was going to be a laborious process to get the engine to run. But this I wasn't ready for. I decided to use up the fuel remaining in the tank using the existing carb settings with short runs of a minute or so each and to allow the engine to cool down completely between these runs in order to help start the seating process for the rings. I only got three short runs because this engine really uses up fuel quickly. Part of this, of course, is related to the fact that I'm using methanol, but right now it seems to be using about an ounce per minute at half throttle. Because of comments I had heard from other builders I wasn't expecting the high temperatures at the heads and exhaust pipes that I'm seeing. After a minute of running, mine are much too hot to touch. Lee had told me the exhausts would be cool to the touch and so maybe when I optimize the carb settings I'll find I need to richen the carb. I spot checked the #2 plug and it looked like new, but frankly methanol isn't going to color the plug in any meaningful way.
The engine started easily by hand for all three one minute runs, and so I decided to quit and celebrate. My next step will be to optimize the carb settings for methanol/Crowne camp fuel. I plan to continue using short runs with cool down between for the first half hour or so of running. I'll also continue to run the oil system open loop for the first hour or so of running.
After I get the carb and timing settings to a point where I can't seem to make any further improvement, I'll take and post a short video before changing over to gasolene or perhaps going back to the Walbro (yeah, ... like that's going to happen). - Terry

 

[cfellows]

Congratulations, Terry! I guess I can breath again. After seeing all the work you've put into this project I probably would have been as heartbroken as you if for some reason you couldn't get it running. But, the truth is, I was pretty sure you would stick with it until you got it going and going well, even if you had to rebuild it from scratch!

Chuck

 

[petertha]

.. your experiences with 4-strokes running hotter head and exhaust temperatures when burning methanol instead of gasolene caught me by surprise.

To clarify, my experience/comment was 4-S engines seemed to run hotter on the exhaust assembly components vs. 2-S engines, but both were typical RC methanol based fuel (+nitro +oil), not gasoline. I do recall measuring this temp increase directly with gauges & thermal crayons because we were struggling with exhaust bits burning up way more frequent than 2S. As to why... the thinking was 2S benefited by cooling from the fresh induction charge even though it was firing less often than 4S. But this is off topic to your gasoline vs methanol point, sorry for any confusion.

I'm trying to find links of (methanol based) temperature & this is about what I could muster FWIW. I don't think my rusty recollection of ~400F is very far off at the exhaust header, but as mentioned, subject to numerous assumptions & variables (engine type, load, avg head temp vs exhaust area temp, prop cooling blast, lean/rich setting, oil content, rpm, boost.... etc.)

http://www.rcgroups.com/forums/showthread.php?t=1598160
http://www.teamflyingcircus.com/forum/f23/cylinder-head-temp-5982/index14.html

http://www.rcgroups.com/forums/showthread.php?t=715078

 

[Art K]

Terry,
Good job getting the radial running. Not surprised it started on the first flip, you seem to be the thorough sort. Nice job, I'm looking forward to the video! I've been following your thread for a bit now, good luck with the minor sorting out.
Art

 

[mayhugh1]

Lakc - good point on the 2x fuel volume and thanks Petertha for your clarification. I mis-interpreted your post.
I spent a few hours making a new but ugly looking set of needles for the Jerry Howell carb on my V-4 to see if I could have any better luck running gasolene. I was hoping to reduce the taper by a factor of two, but there wasn't enough room in the carb for such a shallow taper and so I was only able to reduce it about 20%-30%. I figured any amount would be better than nothing. The bottom line is that I was able to get it to run just fine on gasolene. The new idle needle seemed to have about the same setting sensitivity as my original needle, and so I put the original one back in; and sure enough I got it to idle and run mid-throttle just fine. I found a narrow setting, about a quarter turn, with the new high speed needle where the transition from idle to high speed was acceptable. I put my original high speed needle back in at its original methanol setting, and the transition from idle to high speed stumbled badly. In order to correct this I had to reduce the high speed setting by a full half turn which almost completely shut fuel off to the high speed spray bar. I let the engine cool for several hours and then cold started it. It immediately fired up and ran, probably as good as it ever did on methanol, and the throttle response was as also as good as I'd seen it. I plan to run gasolene in that engine from now on.
Meanwhile, I put some more runtime on the radial. I'm still running a 15% mix of methanol and Crowne camp fuel because I want to see how well I can get it to run on methanol first. I'm continuing to run short 1-2 minute cyles with complete cool down in between and I'm resisting the urge to rev it up to full throttle. The engine starts everytime with just a flip of the prop. My timing is 10 deg BTDC and some cursory checks show that the performance, so far, doesn't seem to be very sensitive to timing advances between 10 and 30 deg BTDC. But then I'm not revving the engine up yet either. Using an IR probe I measured the head and exhaust temperatuures after several mid-throttle runs and never saw them to be over 140F. I'm sure this is probably the 'cool' running exhaust temperature that the other builders have described. I guess I was just too excited yesterday when I was measuring it with my uncalibrated finger and thought the temperature seemed excessive. Still in the back of my mind is my construction error of using SAE-660 bronze for the valve cages, and I don't feel comfortable using this material at 400F-500F.
With a whopping 10 minutes total run time so far I made some rpm measurements so I could calibrate my ear. I was able to get the engine to idle down to 800 rpm while still hitting on all cylinders, and the sound at that speed is incredible. At about half throttle the engine runs at 2600 rpm. At this speed I played with the high speed needle and was able to get the rpm to peak by closing it OFF another 1/4 turn. This means that the high speed needle is now only 1/4 turn open from its full OFF position. It sounds like when I shift over to gasolene I'll probably have to nearly close off the high speed needle as I did with my V-4. I also played some with the idle needle some but +/- 1/4 turn didn't seem to make any difference in engine speed. The fuel consumption is more like 2 ounces per minute at mid throttle.
I'm happy to see that the engine doesn't seem to be spitting or blowing any oil. If I remove the #5 and #6 plugs after shutting down for the day as Hodgson recommends, and then put them back in before starting the engine again the next day the firewall is completely dry. If I leave the plugs in I will get a bit of initial blow-by from the #6 exhaust, and then the engine exhausts run clean. There seems to be a bit of oil seeping past the rings in #6 and dropping onto the plug.
I've included a few photos of the engine running. I want to wait until I'm on gasolene and comfortable with revving it up before I try to make a final video. - Terry

 

[Henry]

Nice, nice , nice .... but now we want to hear it, there is nothing like a radial music!!!!

Congratulations!!!

 

[mayhugh1]

Today I decided to give gasolene a try.
I think I have the carburetor idle and half throttle performance pretty much dialed-in for methanol at this point even though admittedly I haven't yet made any full power runs with it. In summary, my final settings for the Super Tiger model 12163145 carb running on methanol on this engine are: low speed needle is set 1-1/2 turns open from fully closed position and the high speed needle is set 1/4 turn open from its fully closed position. I determined the fully closed starting positions by blowing through a length of clean fuel line connected to the carb fuel nipple (carb off the engine) and listening for air flow through the carb to stop when I turned each of the needles clockwise. The throttle was 95% closed for the low speed test and wide open for the high speed test. I also determined that anywhere between 5-20 degrees of timing advance seems to work equally well at midrange.
If a model engine builder is looking for a reason to change from methanol to gasolene I have two photo pretty convincing photos. In my last post if you look at the photo taken from the rear of the engine while it is running methanol you can see the waste oil container in which I'm collecting the scavenged oil for disposal. If you look closely you will see it is a yellow frothy emulsion. This comes from the fact that the beneficial extra oxygen in the alcohol produces a lot more water during combustion. If the engine (model or even full-size) isn't run long enough and hot enough to get the engine oil up to a temperature where this water can evaporate and escape through the crankcase ventillation system it will remain in the crankcase where it will eventually corrode the steel components inside the engine. And, model engines are hardly ever run up to this point. Compare this photo to the one I took today while running on gasolene and making similar 1-2 minute runs with engine cooling down in between. The oil in this case is cloudy but there is no excessive water emulsion. This is one of the reasons why I have been running the oil system open loop. If the Hodgson's reputation for running 'cool' is legitimate then you definitely don't want to run it on methanol unless you're willing to add a mandatory oil change to your engine post-run maintence list.
I filled the tank with 87 octane and began with the carb settings as they were for methanol. The engine wouldn't start by hand, but it did fire up with the starter. It idled and ran at half throttle, but I had some misfiring and I was getting some oil and fuel out the exhausts indicating that I was (surprise!) running too rich. I played some with the needles, and the combination that I tentatively settled on was: 1) the low speed needle closed another full turn from the methanol position (the needle is now only 1/4 turn open), and 2) the high speed needle closed almost another 1/4 turn from the methanol position (it is now nearly completely shut off). Even though the engine is idling down to a very low speed (still sounds like 800 -900 rpm but my optical tach isn't working in the bright sunlight and so I couldn't get an actual measurement), I now have to keep the throttle open a minimum of about 20% to keep the engine running. With methanol and my previous carb settings the engine idled with less than 5% or so throttle opening. This is likely happening because the low speed needle is now so nearly closed off that I'm just not getting any fuel flow at all with a nearly closed throttle. I stopped the engine and let it cool down. For the next cycle and these needle settings the engine did start by hand and I finished running the gas out of the tank. There was now only a bit of oil/fuel coming out of the exhausts; but no smoke, and so I'm probably close with these settings. The only thing is that both needles are so close to being shut completely off that I'm starting to wonder how consistent these settings will remain over time. If a model engine builder is looking for a reason to not run gasolene in his engine with a methanol carburetor, this will be at least one of them.
I blipped the throttle a few times and the throttle response is there. In fact, maybe it feels better than when I was running methanol. The engine wants to rev up but I'm still not ready. I played with the timing a little, and now the engine seems to want some timing. Right now, I have it tentatively set at 15 deg BTDC. The timing requirements may change again later when I rev it up. My engine now smells like an old gasolene engine. There was never any fuel odor with methanol. After the engine cooled down, I pulled all the plugs and cleaned them. All were sooty black showing a too-rich mixture. Some were also a bit wet with oil. I've never seen soot on the plugs of my other two engines even when the methanol mixture was overly rich. These plugs were probably loaded up when I first started and ran the engine with the methanol settings before I had leaned down the mixture. I guess I've also proven that my ignition dwell, at least at mid-throttle, is adequate to ignite an overly rich air/fuel mixture. I'm going to add a healthy stripe of reflective tape on the back of the prop so I can use my optical tach toe measure the engine rpms on tomorrow's runs. - Terry

 

[mayhugh1]

For the past few days it has been very cool down here; and with the much needed rain we're getting, I decided to wait before doing any more carb tuning. I used the time to re-make the banjo nuts on my oil transfer tubes which have been seeping oil. I originally made a nice pair of decorative nuts from black Delrin, but I did a poor job of threading them; and they were a sloppy fit to the banjos and couldn't be properly tightened. I made new ones out of steel that solved the problem. I also made a simple bracket on the firewall to hold the #5 and #6 sparkplugs for safekeeping during long term storage of the engine. I also made a nameplate that officially delares this project finished this month. I inspected and cleaned all the plugs from my last run. They were all sooty rich but since the needles had been adjusted over such a wide range during the last session it was impossible to tell if the final settings were still too rich. All plugs seemed to be equally sooty and none were wet with oil.
I decided it was time for a video and set up my camera to capture my first start after the engine was allowed to sit for two days.

[ame]http://www.youtube.com/watch?v=oQeuXqu_Gw8[/ame]

The sequence is to 1) turn on the fuel pump, 2) set throttle to w.o.t. and prime the engine by turning the prop over a few times with my thumb over the carb intake, 3) repeat number two but this time with the fuel pump ON dummy:hDe:, 4) set throttle to half open, and 5) turn on the ignition and give the prop a slap. I'm still running the oil system open loop, but I intend to close it after another 20 minutes or so of running. As you can see in the video, the engine starts right up with a temporary cloud of blue smoke as the oil that settled in the lower two cylinders over the past few days is cleared out. In the video I'm tweaking the idle and high speed needles a bit around the settings I ended up during my last session. Before starting the engine I placed a large piece of reflective tape on the rear of the prop so I can use my optical tach to measure rpms. In this video the engine eventually idled down to just over 800 rpm. However, I could not get it to rev up past 3000 rpm. I later found out that I was too focused on the carb mixture and not paying enough attention to engine timing. In a later run after the video was made I discovered that the 2-56 grub screw in the rear engine section that bears against the distributor body and keeps it from rotating had sheared and allowed my timing to shift to ATDC. I have a huge pointer mounted on the rear of the distributor to indicate the timing - I just wasn't looking at it. Unfortunately this grub screw rides in an internal groove cut around the circumference of the distributor tail, and so the distributor is now captive to the engine rear section. If I ever have to remove the distributor body from the rear section I'll have to perform some careful surgery on the still-remaining piece of grub screw. When I manually rotated the distributor back to 20-30 degrees BTDC the engine rev'd up to the point of being scary. So, my next task is to come up with some kind of linkage to allow me to easily adjust the timing and hold it in place. A first look tells me it will be difficult to link it to the throttle lever in the space I have. It probably also means that the carb settings I've come up with so far are suspect. So far the exhausts are not spitting oil. I think Hodgson's oil control rings are doing their job. - Terry

 

[vcutajar]

BEAUTIFUL just BEAUTIFUL.

Vince

 

[metalmad]

Like she said
WOW;D
Pete

 

[ozzie46]

YeeHaaawww! Absolutely beautiful.Thm:Thm:Thm:

Ron

 

[Henry]

That is music sir!!!! I love the sound when idle:bow::bow:th_wav.