Author Topic: Longboy's "SPLIT MONO" Model Engine!  (Read 2627 times)

Offline Longboy

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Re: Longboy's "SPLIT MONO" Model Engine!
« Reply #15 on: August 06, 2023, 05:58:40 AM »
The production con rods are serviceable one at a time without pulling the piston from the bore. They will be drilled for some bushings fixed to the webs and piston for them to swing upon.



Doing primary balance. The piston/ rod assembly is heavy, about 2.7oz. vs. around 1.2 oz. for a conventional one inch bore set and same length rod. Shown is a preliminary with just one web
this photo. A couple of small neo magnets hold some steel rod to the web to find that neutral spot.





Add both webs to the bearing in vice and the correct weight brings the assembly to that 3-9 O'clock unbiased area. Weigh the steel rod samples and start fashioning the counterweights.      :)


« Last Edit: August 08, 2023, 06:12:30 AM by Longboy »
Wadda you mean, "It don't run"???

Offline Longboy

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Re: Longboy's "SPLIT MONO" Model Engine!
« Reply #16 on: August 08, 2023, 06:10:31 AM »
The counterweights are fashioned in brass and bolted to the backside of the web over the gear. Shared between two webs, their size volume is the same as for single rod assemblies.



On the rod big end, a hybrid shoulder bolt. Delrin bushing is threaded to the 6-32 SS socket head
and with blue Loctite, into the web. Great idea! No lube needed here then for the rod to swing upon.




In trouble shooting SPLIT MONO, These big end screws would loosen up and back out! My best guess is even with Loctite, could not get proper torque due to distortion of the plastic bushing in this application area. Remade the bushings in brass.......that problem ended.   :ThumbsUp:
Wadda you mean, "It don't run"???

Offline Longboy

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Re: Longboy's "SPLIT MONO" Model Engine!
« Reply #17 on: August 09, 2023, 07:47:40 AM »
Building up the lower frame. A couple skid bars tie in the upper component support.



Cross wise to these rails, steel foot bars with the rubber bumper feet.



SPLIT MONO being a large single has a small footprint upon the table. Going to add a steel plate between the foot bars. The added weight to quell the combustion vibes.
Now the engine can stand on its own and will be looking for placement of the cam, radiator fan and their drives. Make fuel tank, fuel mixer, valve block and place ignition points.
Wadda you mean, "It don't run"???

Offline Longboy

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Re: Longboy's "SPLIT MONO" Model Engine!
« Reply #18 on: August 10, 2023, 08:10:27 AM »
I like to do forced air cooling if room allows.



For my scale, I have a two inch bulkhead connector in black PVC with 2in. aluminum fan from Ace hardware.



Back of cylinder drilled/tapped for a 3/ 16 in. shaft after PVC is bored and trimmed for fan and mounting to upper deck of frame. The fan can run direct on shaft or thru bearings. A Delrin pulley pressed over fan hub for the drive at near 2:1 ratio.



Some aluminum sheet stock encloses the PVC shroud to the radiator finning by some 2-56 screws into the hex. The fan runs as pull back thru the shroud being driven by the clockwise running crank side.



The lower deck gets slotted for the drive belt and the slot can be of shorter length with an idler pully on the underside. 1/16 in. O-rings used as drive belts not available at this length so elastic pony tail wrap bands from the dollar store are used and they hold up well in this purpose.



And the brass drive pully on the crankshaft!






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Offline Longboy

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Re: Longboy's "SPLIT MONO" Model Engine!
« Reply #19 on: August 11, 2023, 05:09:11 AM »
The fining done on the cylinder and head. A single port entry in side of head covers both intake and exhaust duties to the combustion chamber.




A combination valve block meets the head port transversely. A single specialized bolt with the dual purpose of a fastener and a port created.





Fashioned on 3/8 in. brass hex and through the top block piece threaded in head. O-ring seals under the hex and above the 1/4-28 threads. Bolt is drilled up shank about half way. Torqued down to the cyl head, a hex face is marked with center punch. Then through the valve block port access, drilled through the shank for a T- intersection of both in/ex valves to the engine. The marked spot on the hex is at noon hour for the correct line up of ports.



The valve block with one fastener to head must remain parallel to the deck surface. If it tilts when running, the valve clearances get messed up.
A flat machined in from the bottom of the head ends at where the top of valve block will seat as a wedge preventing any tilt off.



My fuel mixer. The plastic extension needs to be metal as it is too hot here. Now I can locate the camshaft on the frame, the last major component.......... ^-^


Wadda you mean, "It don't run"???

Offline BillTodd

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Re: Longboy's "SPLIT MONO" Model Engine!
« Reply #20 on: August 11, 2023, 10:54:08 AM »
Impressive progress 😁

Just thinking...

Perhaps the next dual crank engine could hav concentric cranks with a bevel reverser  :noidea:

Offline Longboy

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Re: Longboy's "SPLIT MONO" Model Engine!
« Reply #21 on: August 12, 2023, 08:28:12 PM »
The lifter bores are located and drilled in the top deck now that the valve block has been placed. Brass lifter guides inserted and locked in with some set screws from the edge of the deck. Forward from the bores a bearing hangs from the underside of deck to support the end of the camshaft.



Sampling up a geared possibility at the drive end of cam. Not quite right looking. Default back to my usual MXL cogs.



A long brass bushing support at the drive end. The lower deck is cut in from it's edge for the cog flange with the belt on.



Waiting for that belt somewhere on a slow boat from China.



The belts for cam and fan could be lined up so the single guide pulley bracket is replaced for this dual belt guide.



Lifters are drilled for 4-40 socket heads and manage the valve action directly.



 From 3/8 in. leaded steel rounds come the cam lobes. Off set drilled for the shaft and the ramps milled across. #6 set screws lock lobe to shaft. The advantage.......variable valve timing to whatever the engine likes.





Wadda you mean, "It don't run"???

Offline Longboy

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Re: Longboy's "SPLIT MONO" Model Engine!
« Reply #22 on: August 13, 2023, 10:36:26 PM »
Just a couple more items to go before the show here.    :popcorn:

The reliable Tecumseh points set.



Cutting off my fuel filler neck from liquor bottle.



A 2.5 OZ fuel tank on the frame.



Going with a vinyl wrap across the top surfaces of frame in satin grey. Undersides in satin black spray

.

This is what five weeks in the garage looks like! Individual parts and subsets.



.....And you definitely don't want to miss the next posting from LONGBOY ENGINE. - Dave.

Wadda you mean, "It don't run"???

Offline Longboy

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Re: Longboy's "SPLIT MONO" Model Engine!
« Reply #23 on: August 15, 2023, 04:32:03 AM »
Always a great day to introduce a new engine! 🙂 Welcome to Longboy's 'SPLIT MONO" premier.

Another use of my geared together crankshafts successful in four previous builds. In those engines, each crank segment had its own piston.



And you can gear 2-3-4 shafts together with only one of those shafts having a connecting rod and piston driving the assembly. But could one piston drive two crank segments directly? 🤔



And the answer is yes as you see here!  :cheers:



SPLIT MONO build started 1st week Feb. and finished up last week of Mar.



SPLIT MONO I can say ( reasonably) is the 1st model engine built showing bifurcated rods on one piston. It would of been great to also say this is my original idea!



That is not so. Looking through web sources like Pinterest, YouTube and such, I have found only three examples in I/C with this arrangement. One being an educational discussion module on the concept. Another, a motorcycle racing development from the '90s. The third is a current production engine from a German manufacturer as noted by model builder BillTodd in this story. Then you'll have an ideal on how long I spend cruising the internet after shop time! 😉



Looked like it would fit my abilities and fit in with previous surprises around "something different". Maybe another machinist will try this out. It's a single. Its type is sold in the real world. No mystery to the reciprocating assembly. Good luck with your projects and see the video now! .Dave!



<a href="https://www.youtube.com/watch?v=PiyJnac9bAk" target="_blank">http://www.youtube.com/watch?v=PiyJnac9bAk</a>
« Last Edit: August 15, 2023, 04:37:19 AM by Longboy »
Wadda you mean, "It don't run"???

Offline Admiral_dk

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Re: Longboy's "SPLIT MONO" Model Engine!
« Reply #24 on: August 15, 2023, 07:40:14 AM »
Idles nicely + easy start  :ThumbsUp:

I knew of the motorcycle - but couldn't see it being a success, when presented with the idea ....

Per            :cheers:

Offline bent

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Re: Longboy's "SPLIT MONO" Model Engine!
« Reply #25 on: August 15, 2023, 05:53:18 PM »
Cool engine, the build looked fun.  And it runs very well, congrats!  :popcorn: :ThumbsUp:

Will it sell?  Who cares :)

Offline Longboy

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Re: Longboy's "SPLIT MONO" Model Engine!
« Reply #26 on: August 15, 2023, 06:26:47 PM »
Idles nicely + easy start  :ThumbsUp:

I knew of the motorcycle - but couldn't see it being a success, when presented with the idea ....

Per            :cheers:

Diesel motorcycle engines not a popular idea. Neander Motors having better luck with their outboard marine version.

https://www.motorcyclecruiser.com/neander-1400-turbo-diesel-motorcycle-test-review/

Wadda you mean, "It don't run"???

 

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