Author Topic: 8 cylinder Marchetti Radial Cam Engine  (Read 11752 times)

Offline 90LX_Notch

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Re: 8 cylinder Marchetti Radial Cam Engine
« Reply #30 on: March 13, 2017, 11:51:33 PM »
Wesley what an unbelievable project.  Fabulous work.

-Bob
Proud Member of MEM

My Engine Videos on YouTube-
http://www.youtube.com/user/Notch90usa/videos

Offline Wesley_NL

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Re: 8 cylinder Marchetti Radial Cam Engine
« Reply #31 on: September 17, 2017, 07:07:40 PM »
I have finished the project but wasn't completely successful in getting it running properly. Even though it did run very smooth on just two cylinders, it absolutely refuses to run on all eight. This is caused by tolerances on the valves (leading to air gaps and jamming parts) and also friction on the rotating points of the arms.

I have decided not to machine all the parts needed to get this engine (first attempt prototype) to function well. Instead I will use the acquired knowledge to design and build a much better one which I am looking forward to!

Offline Admiral_dk

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Re: 8 cylinder Marchetti Radial Cam Engine
« Reply #32 on: September 17, 2017, 07:51:24 PM »
Your engine looks stunning - a shame that it only runs correct on two cylinders - but as you mention, you know how to make a better version two  :ThumbsUp:

Best wishes

Per

Offline ShopShoe

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Re: 8 cylinder Marchetti Radial Cam Engine
« Reply #33 on: September 18, 2017, 01:44:59 PM »
Amazing.

I'm looking forward to the second one running.

I have patience.

ShopShoe

Offline Jack T

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Re: 8 cylinder Marchetti Radial Cam Engine
« Reply #34 on: October 18, 2018, 11:39:41 PM »
Hi all,

I found this thread a few years back while researching a different cam engine, the Fairchild Caminez 447-C. Thanks to Wesley's impressive work I was inspired to start working on that design to produce an air powered model of my own. Like Wesley I am a student, so progress has been slow, but I am finalizing my designs and hope to start machining in a month or so.

Currently I am working on the cylinders and pistons, and am stumped on how to get the timing for the compressed air figured out. I saw mention of an automatic exhaust valve idea and was curious if you folks knew more. Since Wesley and my projects are similar I though it might be a good approach instead of also designing my own push rods, cam etc.

I don't mean to clutter up this thread but if anyone has any advice that would be much appreciated. Feel free to post here or PM me. This is my first post on this forum so I am not familiar with how everything works yet.

-Jack

Online b.lindsey

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Re: 8 cylinder Marchetti Radial Cam Engine
« Reply #35 on: October 19, 2018, 12:46:27 AM »
Hi Jack and welcome to the forum. Hopefully someone can help answer your question. In the mean time, please tell us a bit about yourself and your interests in the "introduce yourself" section so that those not watching this thread can welcome you as well.

Bill

Offline Wesley_NL

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Re: 8 cylinder Marchetti Radial Cam Engine
« Reply #36 on: October 21, 2018, 08:32:11 PM »
Hi all,

I found this thread a few years back while researching a different cam engine, the Fairchild Caminez 447-C. Thanks to Wesley's impressive work I was inspired to start working on that design to produce an air powered model of my own. Like Wesley I am a student, so progress has been slow, but I am finalizing my designs and hope to start machining in a month or so.

Currently I am working on the cylinders and pistons, and am stumped on how to get the timing for the compressed air figured out. I saw mention of an automatic exhaust valve idea and was curious if you folks knew more. Since Wesley and my projects are similar I though it might be a good approach instead of also designing my own push rods, cam etc.

I don't mean to clutter up this thread but if anyone has any advice that would be much appreciated. Feel free to post here or PM me. This is my first post on this forum so I am not familiar with how everything works yet.

-Jack

Hi Jack,

To hear that my work has inspired you is a great compliment for me ;D. Hoping to hear more about your progress!

About the overhead valves; they are quite special.
Chuck Fellows deserves a lot of credit for showing me the design of his automated exhaust valve:
http://www.modelenginemaker.com/index.php?topic=4021.msg74897#msg74897

I modified this idea and successfully automated both the inlet- and outlet valve. The inlet valve is actuated by the piston and the outlet valve is actuated by the pressure difference with outside air. Attached to this post is an animated gif showing how it works. It required no fine tuning and worked on the first attempt for me, saving a lot of work on the overhead valves.

I uploaded a new explanation and animation for you on my website marchetti-engine.com. You can find under "Prototype (testing) model" the section "Special overhead valves".

-Wesley

Offline Jack T

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Re: 8 cylinder Marchetti Radial Cam Engine
« Reply #37 on: October 29, 2018, 04:54:04 PM »
Thanks for the reply Wesley,

This is a really slick idea. I might give it a go on my engine as well. I did some brainstorming with some other students and this is better and simpler than anything we came up with.

Another question for you. What did you use for compression rings and lubrication on your engine? I figured with compressed air as the energy source, an o-ring with a nice spray down of WD-40 might suffice.

Thanks for your input and good to hear from you,
Jack


Offline Wesley_NL

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Re: 8 cylinder Marchetti Radial Cam Engine
« Reply #38 on: October 30, 2018, 05:57:58 PM »
You're welcome!

Attached is a picture of a piston before assembly. Because there is no large thermal gradient, I chose to leave out the compression rings and accept possible leakage. So quite some time and patience was spent to get tight tolerances.

I recommend that you get one of those filter/regulator/lubricator combinations, see: https://www.hydraulicspneumatics.com/sites/hydraulicspneumatics.com/files/uploads/2014/05/%20F-R-L.jpg. It filters some humidity and particles and simply sprays/evaporates oil into the air stream which lubricates all your components.