Ageless 9 and 18 Radial

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rlo1

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Timing complete, ready for a prop, oil and fuel. Working on the 18 should be ready for start up in a week or so
5B4F7712-EACA-4B48-8CB4-FD4D192AF994.jpeg
 

petertha

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Very nice, best of luck.

Is there any special requirement for the spark plug wires themselves? I've heard different recommendations over time like high strand count, low resistance, minimum gauge size, shielding.... But I'm actually not sure if that had to do with bench mode running vs RC model mode (EMF, radio noise, that type of thing).
 

rlo1

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Hello, Been trying to fire the 9 cyl for two weeks now. I have 4/9 cylinders firing. I am running the Carpenter Cushman carb. I am running S/S ignition. Had tons of crossover CDI issues that I had to address, it seems to have stopped, need to stay vigilant on this. Had to unbundle the loom of wires and will have to redesign wire guides. The 18 waiting for me to finish the 9. I have some revisions to make to the 18 and I want to wait until I figure out these other issues on the 9.

The upper cylinders run lean and the bottom is rich. Still trying to tweek the mixture settings. It is the standard cushman Carter Model N Carb from Carpenter carburetors.

Gapped and regapped the plugs. Running about .025 now.

Compression is improving as I did pressure check every valve in every head before final assembly. The more I spin and sput :) the better the rings get.

Valves are constantly requiring fine adjustments. This is where the most of my focus is. The Cam/Ignition timing seems OK as the plugs are firing just before TDC as required.

I seem to remember some good threads on this forum about these types of issues. Suggestions? Thanks again. I really see why these major builds are so difficult to complete. One cylinder at a time.... :)

BTW, Happy Thanksgiving to Everyone!

-Ron
 

Bentwings

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id run what ever Hogson recommends for advance . Small engines, not that this a “ small” engine don’t realy need a lot. Lawn engines usually have about 28 degrees. They are smal bore so the flame front covers the piston pretty quickly compared to automotive engines with twice the bore size a couple small engine I used in large scale planes had electronic ignitions two had mechanical advance electronic had built in advance. the main purpose was easier starting with less kick back and better low speed , 3000 rpm or so. I did considerable testing but 28 rotatable worked well on most . There has been several guys making clear plastic heads for Brigs and Stratton so yo can clearly see the flame travel , for a while. Yours is only about 1 inc bore so not a lot would be needed. When I looked at the plans I thought there might be a fuel distribution issue the impeller should give pretty good mixing when running but there are still bends in the tubes these can cause fuel to drop out of the mix mix . I had thought about an over drive for the impeller but that got complicated fast I did think about external driving it with electric motor the full size had multi speed and external supercharging . My thought was just fuel mixing . Supercharging this size simply does not work well as others have tried with some cute clever centrifugal units they looked nice but did not function beyond fuel mixing on draw through nuts . I’d be sure you are getting correct timing on each cylinder an maybe make sure you don’t have any low spots on the lower cylinder intakes even it means remaking the intake tubes. The counter to this is others have used it as designed and they run well . As for wires keep them separated . We go to great lengths to keep wires separated on our racers . Once plugs get wet with fuel they don’t do well even full size radials have issues if they don’t use proper starting procedures
Hello, Been trying to fire the 9 cyl for two weeks now. I have 4/9 cylinders firing. I am running the Carpenter Cushman carb. I am running S/S ignition. Had tons of crossover CDI issues that I had to address, it seems to have stopped, need to stay vigilant on this. Had to unbundle the loom of wires and will have to redesign wire guides. The 18 waiting for me to finish the 9. I have some revisions to make to the 18 and I want to wait until I figure out these other issues on the 9.

The upper cylinders run lean and the bottom is rich. Still trying to tweek the mixture settings. It is the standard cushman Carter Model N Carb from Carpenter carburetors.

Gapped and regapped the plugs. Running about .025 now.

Compression is improving as I did pressure check every valve in every head before final assembly. The more I spin and sput :) the better the rings get.

Valves are constantly requiring fine adjustments. This is where the most of my focus is. The Cam/Ignition timing seems OK as the plugs are firing just before TDC as required.

I seem to remember some good threads on this forum about these types of issues. Suggestions? Thanks again. I really see why these major builds are so difficult to complete. One cylinder at a time.... :)

BTW, Happy Thanksgiving to Everyone!

-Ron
 

Bentwings

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spell check did me in again sorry it’s hard enough not seeing well but spell check often won’t even leave my name alone .

When I first saw the drawing set I looked up the cushman carb I thought it to be kinda large for the engine but it’s hard to argue with experience especially from Hogson . He and his dad have done a lot of research an built quite a number of these engine . The cushman scooter was not a real big engine so I’d think that this was a big part of the thinking the 9 and 18 cylinder engine actually have quite a bit of “ operating displacement “ so the carb qualifies But individual cylinders are not much larger than model two strokes of the era they generally had a Venturi / spray bar and needle valve carb so if I remember right when the zhogsons first ran these they did use this type but I YHINK the cushman was more a “ real carb” all around so this became the choice as it was more or less “ full function “ but until till the big engine is running there is not a lot of flow in the intake tubes so it’s easy to get them wet inside That’s why I was thinking about a motor driven impeller to really mix the air and fuel no pressure expected just a lot of thrashing of the air fuel . My thought was that I could have a well mixed mixture in the system and not have to worry about only a weak signal from individual cylinders

Well keep popping you will get there soon . Once it runs even briefly things will start to seal up . I’ve seen video of these starting with a single flip. On the other hand the really expensive model radials like Moki can be very hard to start I see them often using an electric starter



Very nice, best of luck.

Is there any special requirement for the spark plug wires themselves? I've heard different recommendations over time like high strand count, low resistance, minimum gauge size, shielding.... But I'm actually not sure if that had to do with bench mode running vs RC model mode (EMF, radio noise, that type of thing).
 

rlo1

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Got a cool IR camera (Klein Tools) that works with my Iphone from Amazon. It is nice for troubleshooting cold cylinders. Making progress on cold cylinders every run. 7/9 thus far. Happy Thanksgiving all. Enjoy your loved ones. - Ron

FYI, this is one oily engine! Love it!
 

Bentwings

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the cheat laser IR heat gun from harbor freight is worthy of consideration. The dot is the frustum of a cone so distance from the gun is important I forget the ratio but it’s pretty high . In other words you need to be pretty close to the heated object to avoid interference from other sources testing the floor or wall across a room is probabl ok but if something blocks Bart of the cone the reading is inaccurate it’s also not good for taking your own temp unless calibrated for this. The ones at the medical office are specific so that’s why they are used you can use it as a reference one time to another as long as conditions are the same the process is called immesitivity this is the relative reflectsnce It varies with materials copper is different than steel or aluminum . There may be something in the extremely fine printed document that comes with the units. They still do a good job as long as you are consistent in usage I jus measured m hand at 2.1 so body temp is incorrect as it’s not calibrate for this
Got a cool IR camera (Klein Tools) that works with my Iphone from Amazon. It is nice for troubleshooting cold cylinders. Making progress on cold cylinders every run. 7/9 thus far. Happy Thanksgiving all. Enjoy your loved ones. - Ron

FYI, this is one oily engine! Love it!
 

Tim1974

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IT’s prity easy on the 9 cylinder to just feel the exhaust it won’t burn you let’s not over complicate everything
 
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Hi Tim, I agree where you can feel separate exhausts but when they all feed a common manifold the IR thermometer is a good idea to balance cylinders that may not be working properly. On a Naval vessel I was on there were exhaust temperature sensors for monitoring if a cylinder had a problem. 12 gauges on each of 2 engines, to be recorded every hour by the watchkeeper. So we are just doing what is done by professionals, however we do it.
K2
 

Bentwings

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modern top fuel racers have on board data logging ex temps some have intake temps also time line then g loading so every thing is monitored the latest use ir temp reading to get around delay from thermocouples by setting the emitters properly they get near instant temp measurements to plot on the time line rules prevent auto tuning so back at the trailer then crew chief calls for adjustments for the next run the fuel input is timer controlled so it’s the crew chief call when to adjust fuel during the run Cars that have transmissions can also have shifts set according to g load time or rpm even ignition for each cylinder is recorded it can be adjusted for crankshaft twisting. GPS positioning available too so it’s possible to adjust tuning for track position glad I’m out of the race game
Hi Tim, I agree where you can feel separate exhausts but when they all feed a common manifold the IR thermometer is a good idea to balance cylinders that may not be working properly. On a Naval vessel I was on there were exhaust temperature sensors for monitoring if a cylinder had a problem. 12 gauges on each of 2 engines, to be recorded every hour by the watchkeeper. So we are just doing what is done by professionals, however we do it.
K2
 

Bentwings

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IT’s prity easy on the 9 cylinder to just feel the exhaust it won’t burn you let’s not over complicate everything
We had a twin engine b 25 Rc Warbird with scale functioning exhaust one engine would not come up to max rpm properly . In testing I found the short side exhaust much cooler than the long side . I realy didn’t want to just ad length as it meant a 280 deg loop just to get the extra length . But it solved the problem . Both engine then ran less than 100 rpm difference from idle to max rpm Very linear throttle response . By carefully weighing the copper elbows snd tubing there was very little difference in side to side or total weight gain .
 
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Inlet and exhaust pipes are tuned - whether planned or not - because that's what gases do...
A gas moving in a tube will have resonances based on pressure, temperature, pulsation rate, etc. - all of which affect engine performance to some degree.
How much this affects engine running is more black-art than science, but most motorcycle and car makers have mastered the art to increase power/efficiency and reduce noise.
Scaling "older" designs creates new conditions that do not linearly change with scale, so may have more or less effect than on the original engines.
K2
 

Bentwings

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you can see on a smaller scale what P&w faced when these engines were cowled over they went through piles of baffles and endless tests and didn’t have the test equipment we have today . You are right about some things just don’t “scale”
Inlet and exhaust pipes are tuned - whether planned or not - because that's what gases do...
A gas moving in a tube will have resonances based on pressure, temperature, pulsation rate, etc. - all of which affect engine performance to some degree.
How much this affects engine running is more black-art than science, but most motorcycle and car makers have mastered the art to increase power/efficiency and reduce noise.
Scaling "older" designs creates new conditions that do not linearly change with scale, so may have more or less effect than on the original engines.
K2
 

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