Author Topic: Longboy's "SILO" Model Engine!  (Read 908 times)

Offline Longboy

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Longboy's "SILO" Model Engine!
« on: May 19, 2022, 06:08:33 AM »
This image giving me and inspiration for a new model.  :thinking:.....exactly how far can you place those valves from the combustion chamber anyway?


The SILO build coming this weekend!   :stir:
Wadda you mean, "It don't run"???

Offline crueby

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Re: Longboy's "SILO" Model Engine!
« Reply #1 on: May 19, 2022, 02:45:43 PM »
That one will need to run on grain alcohol!!

Offline Longboy

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Re: Longboy's "SILO" Model Engine!
« Reply #2 on: May 20, 2022, 10:26:03 PM »
The frame up for SILO is the same as four other models of mine. A short lower deck piece of alum. angle backside and a tall angle piece for the cylinders.



Don't have the 4 inch angle stock. So I do a ninety deg. mate of two quarter inch flats for the cylinders and bearing carriers.



The bearing carriers will be sitting somewhat lower in the four inch vertical piece for this engine.



Base support is 3/4 x 3/8 in. alum flats. Under these will be a pair of 3/4 x 1/2 in. CR steel bars mounted crossways to give some heft to absorb SILO's vibrations.


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

Offline Longboy

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Re: Longboy's "SILO" Model Engine!
« Reply #3 on: May 21, 2022, 05:07:59 PM »
The short deck gets one bearing carrier as #2 cylinder gets the shaft for the flywheel.



Upon this shaft goes the points cam and the MXL cam drive 20T sprocket. Between the bearing carrier and the sprocket here will be a brass eccentric to balance out the piston/rod assembly on the crank web. A change where previously a counter weight was secured to the back of the crank web using the geared set-up on previous engines. I felt I would need more material mass to make the primary balance.

« Last Edit: May 21, 2022, 05:11:35 PM by Longboy »
Wadda you mean, "It don't run"???

Offline Longboy

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Re: Longboy's "SILO" Model Engine!
« Reply #4 on: May 22, 2022, 08:52:11 PM »
Topside, short deck gets the 40T sprocket and shaft for the cam drive. SILO is a twin cam engine! A transfer punch through the bearing and sprocket locates its position into the vertical cylinder frame piece for its second bearing support.

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

Offline Longboy

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Re: Longboy's "SILO" Model Engine!
« Reply #5 on: May 23, 2022, 07:23:37 PM »
Square tube steel butts up to the vertical with brass bushing and shaft. Picking up the drive with .5 Mod, 24T brass bevel gears.



Cam lobes slipped on shaft and somewhat centered with the cylinders topside. Top of tube trimmed away, A 6-32 socket head fastens the assemble to the deck and SILO has its exhaust set position ready for their valve blocks coming above.



Cam drive shaft continues through the vertical, supported with another long brass bushing to end for another set of the bevel gears.



A bearing carrier is bolted from the inside to the lower valve block plate for the intake cam shaft. Brass valve spring retainers are extra long. Drilled and threaded 6-32 after the spring, the valve stems are threaded to them. A 1/8 in. long set screw locks them to the stem and clears the cam lobe on rotation. Threading up/down on the valve stem varies the effective valve lift duration like a rocker and pushrod assembly.
Wadda you mean, "It don't run"???

Offline Longboy

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Re: Longboy's "SILO" Model Engine!
« Reply #6 on: May 24, 2022, 07:40:34 PM »
Tecumseh points set to the lower deck vertical. Convenient wire connection right at the frame edge.



The crank webs are low in the frame and the cylinder deck is high. Connecting rods end up longer and the reciprocating assembly is heavier then.



The brass counterweight on the flywheel shaft. 3/4 in. round offset 1/4 in. from centerline and drilled 5/16 in. to slip over shaft then. Two 8-32 set screws lock it to flats on the shaft and take care of the primary balance.



Over to #1 cylinder , the stub shaft is 5/16 in. , turned down for 1/4-28 thread and a final end 3/16. in. The items in view are spacer, spring washer, threaded counterweight, lock nut and the 2:1 brass gear drive pair for distributor topside of deck.



And in the shop.....sum guy with that look of, "sometimes seems to know what the hell he's doing here"! 👏👏👏



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

Offline Longboy

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Re: Longboy's "SILO" Model Engine!
« Reply #7 on: May 26, 2022, 07:45:41 AM »
The black diagonal object is a frame brace. Two flats bolted together at 90deg. will flex more than real angle pieces and the horizontal component with the cylinders firing off shoots the stabilities away. Mounted between the cylinders....even this brace was not enough to quell the diving board action seen once up and running. You can't beat a four corner box mount, so SILO has a pair of round stock posts at its front corners. That ended the flex issue.

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

Offline Longboy

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Re: Longboy's "SILO" Model Engine!
« Reply #8 on: May 27, 2022, 07:01:16 PM »
A block of Delrin and my home developed fuel mixer meters the fuel feed to the valve block.



I spent a couple days working a vapor feed to SILO. I like the novelty and simplicity of these....but couldn't make it work well enough here. :( Seems like the fuel level in the tank has to be constant or you fiddle with the valve feed endlessly. They seem to work better using a jar instead of a tube and for single cyl. engines. Save for another application someday.

« Last Edit: May 27, 2022, 07:06:36 PM by Longboy »
Wadda you mean, "It don't run"???

Offline Longboy

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Re: Longboy's "SILO" Model Engine!
« Reply #9 on: May 29, 2022, 05:22:34 PM »
The tough part on the build was to bring up the connection from the valve blocks into the cyl. heads. Just not going to come straight up and curve into the front and back of the heads.



I had a couple of these 1/8 in brass compression fittings in a tray. Re-drilled them for 5/32 in. tubing, the nuts are 5/16 -24 and the other end is resized for 1/4-28 thread. Washer and O- ring to the valve blocks and O-ring to the tube under nut to make the air tight seal. SILO needs 10 of these @ $3.79 each at Ace Hardware. 🤔 I made my own with 3/8 brass hex stock and partied on to Burger King for a couple of lunches on the savings!  :DrinkPint:



With the porting into heads at the side, I'd have a little more tube length to work with. My tube bender has a 5/16 in. radius,
 so even with the stiff brass tubing I could make the bends needed and get them into the fittings.



After a couple of throw away samples, I managed to get the four tubes pretty symmetrical in the fit. K&S Metals does have 5/32 in. tubing in more malleable copper.....so I did have an alternative if needing to work in a tighter radius bend by hand for SILO.   :ThumbsUp:
Wadda you mean, "It don't run"???

Offline Admiral_dk

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Re: Longboy's "SILO" Model Engine!
« Reply #10 on: May 29, 2022, 10:23:07 PM »
I see that you still manage to come up with several solutions, that I would not even dream about (my brain is kind of locked into what I know)  :ThumbsUp:

Still following  :cheers:   :popcorn:

Per

Offline Longboy

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Re: Longboy's "SILO" Model Engine!
« Reply #11 on: May 30, 2022, 06:34:31 AM »
Thanks Admiral. That is understandable. Machinists are tied to blueprints as a part of their journeyman program.  I know machine tools from a diploma program at my community college and can depart from protocols in a creative manor to get that uniqueness into my engines. Out in the commercial world, no one would let me build 5% of a million dollar project unless made to strict and proven customer specs...... regardless of my home grown creativities!   :ShakeHead:     Dave.
Wadda you mean, "It don't run"???

Offline Longboy

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Re: Longboy's "SILO" Model Engine!
« Reply #12 on: May 30, 2022, 08:23:33 PM »
Cylinder heads same diameter as cylinders. Just a sparkplug on top and the profile presented is somewhat of a silo with filling chutes.



For those who have not seen the business side of geared together crank webs. Where an over hung crankshaft is combined with multiple cylinders.



To vary the gear lash to prevent binding or clatter in operation, one of the bearing carrier mounting holes in the vertical frame member should be oversized a few thousands and the screw holes on the carrier's flange oversized so you can shift the crank web slightly in/out its counterpart on the other shaft for the mesh.



My ideal size for flywheels in this scale are 3.75-4 inch dia. / .750- 1 inch long. Preferred material is 12L14 steel or brass. Fits on the mini lathe and does take 2- 3 hours of cuts to fashion. I can sneak my models to run under a thousand RPM then!  ^-^



COMING NEXT. THE PREMIER OF THE SOLO ENGINE!    :popcorn:
« Last Edit: June 01, 2022, 07:20:39 AM by Longboy »
Wadda you mean, "It don't run"???

Offline Longboy

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Re: Longboy's "SILO" Model Engine!
« Reply #13 on: May 31, 2022, 02:59:20 PM »
WELCOME TO LONGBOY'S PREMIER OF THE SILO MODEL GAS ENGINE! 👏 👏 👏

SILO turned out pretty good for me. Only thing new in design was the placement of the valve blocks adjacent to the cylinder deck and their plumbing routes up to the heads.



SILO was started the 1st week of Febuary.



And completed the last week of March.



Bore and Stroke: 1x1-1/8 inch.



Free air cooling. Will idle 800-900 RPM range.



A milestone year for me! Ten years of wildcatting I/C designs after the plan built Webster. (15 gas engines) I'll have to go to Home Depot and get one more shelf board and brackets to add to the wall for display now! ☺ SUMMER BREAK IS HERE! Happy Modeling to you from LONGBOY ENGINES!     Dave!



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

Offline Admiral_dk

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Re: Longboy's "SILO" Model Engine!
« Reply #14 on: May 31, 2022, 04:07:23 PM »
Congratulation on the Jubilee Dave  :cheers:

Another fine runner from you - happy Holidays  :cheers:

Per

Offline Don1966

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Re: Longboy's "SILO" Model Engine!
« Reply #15 on: June 01, 2022, 12:30:43 AM »
Awesome results... :Love:



 :cheers:
Don

Offline Dave Otto

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Re: Longboy's "SILO" Model Engine!
« Reply #16 on: June 01, 2022, 01:09:12 AM »
Nicely done!

Dave