Author Topic: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.  (Read 4861 times)

Offline Longboy

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #15 on: October 03, 2021, 05:22:06 PM »
The lower end of SQUARE FOUR. Looks like the start of a donkey cart or pull toy. Bearing end plates set the spacing between the vertical plates.



Trying out a set of 1Mod 20T helical cut bevel gears over straight cut bevels used on the SIDE SHAFTER engine. Checking the three gear fit before bearing carrier install in the end plates. I like them though not sure if better here than using the straight cut versions.



The flywheel end will have a pair of R1810RR shaft bearings with the nose end having one bearing. Between the gear and inside bearing goes another brass tube spacer to set the gear lash with minimum thrust movement of shaft after the end plate receives its bearing carrier.

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

Offline RReid

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #16 on: October 03, 2021, 08:29:11 PM »
Quote
Looks like the start of a donkey cart or pull toy.
Or a BattleBot! And I love those siamesed cylinders.  :ThumbsUp:
Regards,
Ron

Offline Longboy

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #17 on: October 04, 2021, 09:12:59 PM »
  Conventional V twins could suffer from the front cylinder tightening. Nothing about air cooling, the rear cylinder receives most of the oil thrown up from the crankcase.
AVTUR
[/quote]

That is two reasons that kill engines. Over heat and under lubed. Most air cooled issues seem to be at stop and go rush hour traffic conditions @ 90F/30C and higher temps that have a chance at recovery when you can get rolling. Got to move that air as well as spray those cylinders with oil!     .....Dave.
Wadda you mean, "It don't run"???

Offline Longboy

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #18 on: October 05, 2021, 09:36:21 PM »
On the nose end plate backside go the ign. points.



A slot milled into the end of the vertical plate for the insulated connection to coil.



Lead for the condenser and a quick connect spade goes under the screw nut for the 6 volts.

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

Online Admiral_dk

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #19 on: October 06, 2021, 11:10:44 AM »
Interesting configuration for the Crank etc. - will it be a 'Waste Fire' Ignition ?

Per

Offline steamer

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #20 on: October 06, 2021, 11:18:39 AM »
LOL I recognize those gears!    Keep it coming Longboy....this is an interesting build for sure!

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline Longboy

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #21 on: October 08, 2021, 05:44:40 AM »
The cyl. heads overhangs the outboard side of the block.



On the low side of block, a shallow cut mill run up its length for the lifter bar.



Installed, the pushrod will pass through the head to the exhaust valve only rocker arm on top.



Completed Lifter bar with camshaft attached.

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

Offline Longboy

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #22 on: October 10, 2021, 05:17:53 PM »
The cam drive......belt or geared?



Drive cogs are seven inches apart. Gonna need a belt longer than my shoe laces and three idlers in this scale. Going to do gear drive in seven gears from the cam sprocket for a more compact arrangement.

Transfer shafts off the sprocket shaft through vertical plates to the cams. All shafts here brass bushed. All gears .5 Mod/ 24T



Shaft support bushing bolted under heads intersecting the cam drive with the final gear pair.





And the shaft disappears to the back of engine to drive another item!

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

Offline Longboy

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #23 on: October 12, 2021, 05:39:10 PM »
Tail end of this shaft drives the distributer. Using a 3/4in. inner dia. PVC end cap with #8 brass screws for the wire leads. Extended length brass bushing pressed into aluminum body for the dist. shaft to rotate in.



Easy placement upon a pair of 1/4in. rounds on the shaft end plate, the body sits high on the engine.



Will not need too much flywheel back set from it's bearing carrier to clear the distributor gear set.

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

Offline RReid

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #24 on: October 12, 2021, 08:22:14 PM »
I'm enjoying following along on this build. Very clever approach to fabbing a distributor! :ThumbsUp: :popcorn:
Regards,
Ron

Offline Longboy

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #25 on: October 14, 2021, 06:38:51 PM »
Using collet locker to join flywheel to their shafts pretty exclusively over the years. A three bolt retainer squares up the flywheel to its shaft for a true run. I use Delrin collets slit on one side spaced out with a brass or aluminum tube over shaft to a length that extends the collet past the shaft end about an eighth to 3/16th inch.
To free the flywheel from its shaft for service you need a release mechanism. Unlikely one could tap at the flywheel with a mallet to drive the flywheel back off the collet and not damage the engine.



A couple of 8-32 machine screws are threaded into the end plates at a spacing equal to the through holes around the flywheel. Flat washers on the screws push the flywheel off the collet that bottoms upon the brass spacer behind then.

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Offline Longboy

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #26 on: October 16, 2021, 05:59:20 PM »
Sometimes the price of parts one uses building models hits me the wrong way. Gives you a chance to find substitutes for these particular items......or an opportunity to develop your own.



The top of the electrode diameter on a CM-6 sparkplug.



I take a 3/8in brass round for the wire terminals. Offset in the lathe chuck for a thin/ thick side and tap drill for an 8-32 set screw. Finish drilling with an "A" or 15/64 in. drill to the depth of the top of electrode to where it meets the ceramic, around .230 in. Tap the 8-32 threads to the end of the length of terminal then.



The thick side at the threaded top side of terminal is cross drilled the diameter of the wire insulation. Tucked into the hole and the set screw locks in the stripped end copper wire.



Finished length of these terminals is under 5/8th inch and do not overwhelm the small size of these plugs. I think when I do these again, I will thru drill and tap the 8-32's and start the set screw from the top side!
Wadda you mean, "It don't run"???

Offline Longboy

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #27 on: October 20, 2021, 06:42:59 AM »
Atmospheric intake valves seem to be winning in my designs. Even more so integrating into SQUARE FOUR being to the inboard of the cylinder heads. Space being at a premium here for another cam drive.



Pair of aluminum flat stock pieces (from a previous model shown) sandwich the valve guides sealed by O-rings between as well as the mounting to the heads with a brass tubing between these valve blocks and head.





Long machine screws adjacent to the ports hold the blocks to the heads. With the intake plumbing in place, there is no room for a screw driver or Allen key to mount them to the heads. To get a grip on the screws, I straight knurl across 5/16th threaded rod. Drill and tap 6-32. Cut to a short length and thread up to the head of the machine screws with epoxy to lock them on. Now I can tighten down with my index fingers!  :ThumbsUp: I use the same type finger nuts setting rocker arm clearance too.
I'm going to need some short 90 deg. elbows right out from the carburetor port side from here. I can make them.....or see what my friendly ACE Hardware store has to use.........
Wadda you mean, "It don't run"???

Offline Longboy

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #28 on: October 22, 2021, 07:54:15 AM »
From RAINBIRD Irrigation Systems, I find some 90 deg elbows that fit in nice to the valve blocks the inch and three-eights distance between them. They are the right kind of rigid plastic for use here.



Just cut off the barb and press fit into the port up to their flange. Aim them to the front of engine.



Cut up some pieces of vinyl tubing to bring up to the intake manifold. Vinyl pretty heat sensitive so most likely substitute silicon tubing for the job.



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

Offline Longboy

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Re: LONGBOY'S "SQUARE FOUR" MODEL GAS ENGINE.
« Reply #29 on: October 24, 2021, 08:11:10 AM »
Intake manifold here of some black plasticky stuff is drilled for the plenum.



Bolts onto the lower valve block pieces with a couple of spacers. An O.S. carb will feed the engine.



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

 

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