# Four stroke three cylinder radial of my own design



## cooksservices (Feb 16, 2020)

Hey guys, here is my latest engine. I have been working on it for a little over two months in between buying a house and family duties. I promised my self that I would stretch this one out and enjoy the build a little more but once I get going I spend every spare minute in the workshop. My first two engines were built using only my myford ml7 but taking delivery of a Bridgeport mill this allowed me to be a bit more adventurous with this project and a great one to learn milling operations. It’s  amazing how nice it is to use a real mill after doing so much milling with the lathe!


This engine is a 27cc crankcase induction three cylinder four stroke radial engine.

It has three separate gear driven camshafts at the rear of the engine.

The ignition is taken care of by three sets of contact breaker points opened and closed by eccentric cams on the rear end of the cam shafts.

I have no plans for this engine as i built it with total freedom as I went along. Some pars were governed simply by what sizes of material I already had in my minimal stock pile.


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## johnmcc69 (Feb 16, 2020)

Great work sir!
 It takes a lot to go off the deep end, design, & build your own engine & make it run.

 Great job, keep them coming!

 John


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## gld (Feb 17, 2020)

Very nice. would like to see it run, but

video not available to me.


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## Mechanicboy (Feb 17, 2020)

Video unavailable..


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## cooksservices (Feb 18, 2020)

Ohh no!! It seems my video has been banned as the radio was playing in the back ground I don’t have the rights to play that music! I’ll get another video up ASAP


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## gld (Feb 18, 2020)

Who is WMG?


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## petertha (Feb 19, 2020)

Very impressive and unique. Cant wait to hear it running.

What influenced the design of the piston? It has a profiles dome crown & what appears to be wider ring groove. Just curious.


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## cooksservices (Feb 19, 2020)

I think WMB is Warner media group. I have shortened the video to remove the radio from the background hopefully this will be ok. If not I’ll make another video. Rest assured that that I have now made a nice throttle linkage so that I don’t have to reach behind the prop to rev up the engine . I just designed the pistons so hat they look nice the dome doesn’t really serve a purpose as the engine has a large squish. The pistons are around 4mm from the cylinder head at tdc. I didn’t want this engine to have too much compression. The large ring groove is for the viton o rings that I have used for piston rings. I do feel this is somewhat cheating but is s nice way to prove an engine design. I could make some cast liners and new pistons with cast rings at a later date. 

I have over 400 pictures of machining operations if any one would like to see how anything specific was made. 

Thanks for looking .


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## xpylonracer (Feb 19, 2020)

Looks very good and sounds even better, how much running time will those "O" rings provide ?


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## minh-thanh (Feb 19, 2020)

Congratulations ! Great engine, great sound.


cooksservices said:


> I have over 400 pictures of machining operations if any one would like to see how anything specific was made.


I and many people really want to see how it was made
Please !


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## cooksservices (Feb 19, 2020)

I’m not sure how long the o ring piston rings will last but the ring groove is designed not to put too much pressure on the cylinder wall and let the compression push the o rings out. This way they are only really wearing mostly on the compression and ignition stroke. I have read a few articles on here about using viton o rings as piston rings and this is where I took my information from. It seems to work well, the engine has now run just over 750ml of standard pump fuel with 60/1 two stroke mix and it doesn’t have too much friction and seems to bounce well on compression.

Is there anything in particular that you would like to see? As I have so many photos I’m not sure how many I can post on here.

Thanks for all the great comments guys


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## awake (Feb 19, 2020)

Looks and sounds great! Any chance of making plans available?


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## mnay (Feb 19, 2020)

Wonderful.  Love the sound. Beautiful engine.
Mike


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## xpylonracer (Feb 19, 2020)

If you have a Dropbox account you could load all of the pictures to that and then post a link for people to view the folder, just a suggestion.

xpylonracer


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## cooksservices (Feb 19, 2020)

sorry I have never heard of drop box, I’ll look into it


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## Rickus (Feb 19, 2020)

I LIKE it.  I don't have the knowledge to design an engine and you impressed the heck out of me.


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## minh-thanh (Feb 19, 2020)

cooksservices said:


> Is there anything in particular that you would like to see? As I have so many photos I’m not sure how many I can post on here.


On the forum : Each department has some images that you like
If you want more, Google drive is a suggestion
 Again, Great engine !


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## johnmcc69 (Feb 19, 2020)

I would like to see more of the induction set up & a back view of the engine.

 John


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## NickP (Feb 20, 2020)

Love the sound of your engine Cooksservices - your workmanship looks great. I can already imagine it in a scale Lysander doing low my slow passes down the runway!
Like others have said; I’d love a copy of the drawings, but I believe you said you didn’t make any and built it using the stock you had available. That’s a shame but, as much as I’d love to see the plans, if I’m honest with myself about my abilities I’d probably not be able to make one and get it to run  
Would love to see any/all the pictures you have taken - especially your set ups (really important to a beginner like me). 
Thanks for posting. Nick


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## awake (Feb 20, 2020)

Cooksservices, if you don't have plans, I think with pictures plus measurements of key bits (and of how they assemble) one could make reasonably accurate reverse-engineered plans. Am I volunteering? Well ... let's say I'm strongly tempted. I know there are others here who could do a better job, but ... maybe ...


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## accelo (Feb 20, 2020)

I am interested in how you built the intake scoops.   They look wonderful and add a nice visual to the motor.


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## cooksservices (Feb 20, 2020)

awake said:


> Cooksservices, if you don't have plans, I think with pictures plus measurements of key bits (and of how they assemble) one could make reasonably accurate reverse-engineered plans. Am I volunteering? Well ... let's say I'm strongly tempted. I know there are others here who could do a better job, but ... maybe ...



There are a couple of people that have offered to do plans for this and one of my other engines too. The trouble with this engine is that the main crank pin is large for the master rod size so that has compromised the size of the link rod bronze bearings. I think if I were to design that part again I would slim down the main crank pin to share a bit of room with some bigger link rod pins. This is something we will have to look at if we make some plans for the engine. Apart from that I am really happy with how everything has worked out. Especially as every part of this engine was made totally on the fly. I have fired up a drop box account and stuck around 300 photos of the build some good, some bad and some ugly but I haven’t hidden any part of this build. I have only had a mill for two months and a lathe for around two years so my set ups and operations may well not be the right way to do things but I know they worked for me. I hope that this will inspire other less experienced members here to just have a go. With a little imagination and some common sense it’s quite simple to design fixtures and set up parts for machining. If it doesn’t look like it will hold it probably won’t, if it looks like it’s going to dig in it probably will. I was quite surprised with the milling machine how much of the work is in the setting up. Generally it seems that actually taking the cut is the quick part.

I’m not sure what order the pictures are are going to come up so it might be worth clicking to sort the photos by the date they were modified, that way you should be able to scroll to the bottom then work through from the start of the build.

https://www.dropbox.com/sh/myi7t57zxx82hr7/AABtWzR52Rx9V6OHttBfN-hba?dl=0

I am more than happy to answer any questions on the set up and build.

Thank you again for all the great comments!


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## cooksservices (Feb 20, 2020)

accelo said:


> I am interested in how you built the intake scoops.   They look wonderful and add a nice visual to the motor.


 Those are actually the exhausts, I designed them with two things in mind, one was that I wanted them to give a performance classic aero kind of look and also in the hope that they would echo slightly and amplify the exhaust note. They don’t really sound quite as sweet as it did with straight slash cut pipes but much louder and I absolutely love the way they look! 

I made a solid steel former and beat some steel sheet around them from either side to make two halves then trimmed the two halves down and very gently mig welded the two halves together. Lots of filing and sanding later I had three nice looking exhausts. I then welded in some steel tube the make spigots to fit in the exhaust mounting flanges that were then welded on and drilled out again. There is some pictures in the drop box album that hopefully match up with this description.


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## NickP (Feb 21, 2020)

cooksservices said:


> There are a couple of people that have offered to do plans for this and one of my other engines too. The trouble with this engine is that the main crank pin is large for the master rod size so that has compromised the size of the link rod bronze bearings. I think if I were to design that part again I would slim down the main crank pin to share a bit of room with some bigger link rod pins. This is something we will have to look at if we make some plans for the engine. Apart from that I am really happy with how everything has worked out. Especially as every part of this engine was made totally on the fly. I have fired up a drop box account and stuck around 300 photos of the build some good, some bad and some ugly but I haven’t hidden any part of this build. I have only had a mill for two months and a lathe for around two years so my set ups and operations may well not be the right way to do things but I know they worked for me. I hope that this will inspire other less experienced members here to just have a go. With a little imagination and some common sense it’s quite simple to design fixtures and set up parts for machining. If it doesn’t look like it will hold it probably won’t, if it looks like it’s going to dig in it probably will. I was quite surprised with the milling machine how much of the work is in the setting up. Generally it seems that actually taking the cut is the quick part.
> 
> I’m not sure what order the pictures are are going to come up so it might be worth clicking to sort the photos by the date they were modified, that way you should be able to scroll to the bottom then work through from the start of the build.
> 
> ...


Thanks for sharing the pics and videos - really helpful to see how you’ve done things.


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## Brian Rupnow (Feb 21, 2020)

Congratulations on a beautiful running engine. That is very impressive.--Brian Rupnow


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## cooksservices (Feb 21, 2020)

Thank you Brian, that means a lot coming from you.


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## awake (Feb 21, 2020)

Thanks for the pictures! If you get a chance, I'd love to know some of the basic measurements: bore, stroke, diameter of crankcase, that kind of thing.


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## cooksservices (Mar 4, 2020)

awake said:


> Thanks for the pictures! If you get a chance, I'd love to know some of the basic measurements: bore, stroke, diameter of crankcase, that kind of thing.



Hi I’d happily tell you any dimensions that I can remember or that can be measured from the outside. There is a couple of people that would like some slightly more detailed measurements to draw up some plans, I’d be happy to note them down too if I ever strip the engine down.  Thanks, Sam.


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## awake (Mar 4, 2020)

Here's what I am particularly interested in:

Measurement from the outside:

Cylinder diameter
Crankcase diameter (approximate)

If you remember or if/when you strip down the engine:

Bore
Stroke
Size of valves
diameter of crankshaft
diameter of camshafts


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