Author Topic: Horizontal Air Cooled Engine  (Read 12301 times)

Offline Brian Rupnow

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Horizontal Air Cooled Engine
« on: October 31, 2021, 07:27:23 PM »
Yesterday I finished designing a welding fixture for one of my old customers. Earlier this week I redesigned one of the cylinder heads for my opposed twin engine, seeing how I could relocate the sparkplug up near the top of the cylinder head. I don't really want to mess with a finished engine, so I decided to design a new engine to go with my redesigned cylinder head today. Of course this leads me right down the garden path, and seven or eight hours after I think of it, I've designed it. This engine will be air cooled, and will have two valves and a throttled carburetor. I've put a 2" diameter fan on it, and even designed a fancy fan shroud to support and guard the fan blades. I'm not sure when I will get around to building this one, but  winters coming and I will need something to do----


Offline Brian Rupnow

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Re: Horizontal Air Cooled Engine
« Reply #1 on: October 31, 2021, 07:30:50 PM »
And a couple more views so you can see where this one is going---


Offline Roger B

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Re: Horizontal Air Cooled Engine
« Reply #2 on: October 31, 2021, 07:48:30 PM »
There's always another idea to try  :)  :)  :)  :ThumbsUp: My list is still expanding  ::)
Best regards

Roger

Offline Admiral_dk

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Re: Horizontal Air Cooled Engine
« Reply #3 on: October 31, 2021, 10:00:12 PM »
Looks fine to me  :cheers:

Offline Brian Rupnow

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Re: Horizontal Air Cooled Engine
« Reply #4 on: November 01, 2021, 10:28:22 PM »
Today I made the first part for this engine, the cylinder mounting plate. I used my new bandsaw, and what a wonderful bandsaw it is. It zipped thru the aluminum as if it was butter. This is the first part I have made using the new bandsaw, and all I can say is, I wish I'd bought it ten years ago!!!

« Last Edit: January 01, 2022, 01:54:37 PM by Brian Rupnow »

Offline Brian Rupnow

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Re: Horizontal Air Cooled Engine
« Reply #5 on: November 02, 2021, 01:08:22 AM »
People on another forum commented on how ugly that carburetor arrangement was. The more I looked at it the uglier it looked. I haven't built anything on the head yet, so I was able to go in and change it---carb comes straight out the side now. I left that big air horn that was on the front of the carburetor off too

Offline Jasonb

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Re: Horizontal Air Cooled Engine
« Reply #6 on: November 02, 2021, 07:30:54 AM »
Earlier this week I redesigned one of the cylinder heads for my opposed twin engine, seeing how I could relocate the sparkplug up near the top of the cylinder head. I don't really want to mess with a finished engine, so I decided to design a new engine to go with my redesigned cylinder head today.

Brian unless I'm missing something how will this redesigned head get the spark plug near the top of the cylinder on the opposes twin. That has the pushrods above the cylinder which will put the new angled sparkplug at the bottom where it was before :headscratch:

Offline GordonL

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Re: Horizontal Air Cooled Engine
« Reply #7 on: November 02, 2021, 10:35:46 AM »
Your break from engine building did not last very long. It is hard to break old habits/hobbies.

Offline Brian Rupnow

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Re: Horizontal Air Cooled Engine
« Reply #8 on: November 02, 2021, 12:33:35 PM »
Jason--Look at the very top model. You will see what I had in mind to turn the cylinder head upside down so the sparkplug would be at the top of the cylinder head.

Offline Jasonb

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Re: Horizontal Air Cooled Engine
« Reply #9 on: November 02, 2021, 01:07:44 PM »
But the push rods are at the top on the twin and the rocker support would go right across the spark plug and the original carb layout would also have got in the way? You will still have the arching issue even if you can get the spark plug at the top.
« Last Edit: November 02, 2021, 01:20:55 PM by Jasonb »

Offline crueby

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Re: Horizontal Air Cooled Engine
« Reply #10 on: November 02, 2021, 01:39:50 PM »
Jason - he is not remaking the twin, he is designing a new engine, it has the pushrods at the bottom in his new design, look at the pictures in this thread again.

Offline Jasonb

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Re: Horizontal Air Cooled Engine
« Reply #11 on: November 02, 2021, 02:39:33 PM »
Chris, see my quote from earlier today, Brian says he has designed this engine to test the redesigned head for the twin as he wants to test the head design before pulling the twin apart unless I'm not reading it right.

"Earlier this week I redesigned one of the cylinder heads for my opposed twin engine, seeing how I could relocate the sparkplug up near the top of the cylinder head. I don't really want to mess with a finished engine, so I decided to design a new engine to go with my redesigned cylinder head today."

No problem with turning the head upside down but I can't see it working on the twin unless the crankcase is also turned upside down to put the pushrods at the bottom like this single.
« Last Edit: November 02, 2021, 02:50:56 PM by Jasonb »

Offline crueby

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Re: Horizontal Air Cooled Engine
« Reply #12 on: November 02, 2021, 03:05:40 PM »
Hi jason,


The last sentence of what you quoted says it, he is designing a whole new engine. Not a twin. The cad renders all show a single, pushrods on the bottom.


 :cheers:

Offline Jasonb

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Re: Horizontal Air Cooled Engine
« Reply #13 on: November 02, 2021, 03:08:59 PM »
I don't disagree with that but as it is the redesigned head also destined for the twin how will it work with the pushrods so close to the plug when Brian makes a pair to put on the twin?

The image i poste din post #9 shows how this redesigned head would fit if put on a twin, see how the plug is positioned. Mine and Brian's are both based on the Nemett design so unless major work was also done to the rockers, rocker bracket and rods there is the problem or arcing and maybe even the rods hitting the plug cap.
« Last Edit: November 02, 2021, 03:12:57 PM by Jasonb »

Offline Brian Rupnow

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Re: Horizontal Air Cooled Engine
« Reply #14 on: November 02, 2021, 08:02:11 PM »
Today was spent making sideplates. They are finished except for tapping a bunch of holes. I have used up my entire day machining these parts, and will do the tapping tomorrow.