Longboy's "THREE BELOW" Model Engine!

[Longboy]

Moving parts around to gain a lower profile stance on a vertical engine. THREE BELOW's story coming this weekend!

[Longboy]

On the 4x4 inch aluminum angle, my main frame piece. Setting up the bore centerlines for 3 cylinders. The hole thru is liner diameter plus to pass through.



Parting off the DOM cylinder liners. One inch bores.



The radiators with the liners into the frame.......



......and locked to the frame with these half inch tall collars via a pair of #6 -32 flush mount socket heads.

[Longboy]

The crankshaft base plate. Con rod centerlines scribed and the two cross milled slots for the center main bearings.



Brass stock for these bearings. A pair of holes drilled and threaded 6-32 adjacent to the shaft hole drill thru.




Caps then sawed off and the cut is milled flat. The threads drilled out of the caps, bolted to their base and at the center of the joint the drill thru for the shafting commences.



A single #6 socket head secures the bearing block to the crank base plate and a 5/16in. center punch checks out the alignment.   



And placement before the bearing work!

[Longboy]

The crank webs of leaded steel are made by the pair. Quarter inch dia. throw pins to a reamed hole thru. 5/16 CR shafting is straight knurled and pressed in after the part off. Pairs are marked with center punch for sequence and direction and reside between each main bearing.



The #8 set screws lock in to flats milled across the pins with blue Loctite. For the brass center bearings, a couple of brass washers between the webs and bearing with some clearance for crank thrust as well as washers for the flat faced connecting rods side to side movement.



And sampled into the base support bolted to the 4x4 frame.   

[Longboy]

The outboard bearing carriers are mounted in some galvanized eighth inch angle brackets.



This not working for me.    Has to be integrated more into the four inch angle frame than just a pair of screws for a long pieced crankshaft. Looking into my scrap bin......



.....I find a short leg piece of alum. angle with parallel leg to bolt to the 4 in. horizontal! Looks beefier/better with quarter inch material here. Bearing carrier brass is longer on the flywheel end of crankshaft to spread the R1810zz bearings apart within for that two pound flywheel coming.



At the other side is a similar piece but with the leg piece bolted to its top and over to the four inch. Only had that single one piece for the flywheel end of crankshaft!



Now I have the ends of the four inch angle boxed for stability of the frame members between the cylinders/ crankshaft and no flex vibes showing up on combustion!   

[Admiral_dk]

Current version look much better than the Iron bracket 

Per         

[Longboy]

The 20T MXL cam drive sprocket inboard on the flywheel end of crankshaft. Its belt has to rise and head 90 deg. out to the camshaft.



A dual idler bracket gets this done. A couple of half in. dia. brass pulleys on eigth in. rods provide a topside ride over of the belt.



Some Delrin buttons cover the end of the pins in an interference fit.....



.....and on their threaded sides, a couple of acorns to be added for the finish. The bracket bolts to the end of the crank base plate near flush with the bearing carrier plate.



With the 4x4 angle installed to the lower end, a notch out cut in for the belt exit. The proper belt length will be measured when cam install mounting is determined.   

[Longboy]

The crankshaft base is the backbone that the 4x4 angle and bearing carrier end plates bolt to.



The aluminum shoe bar supporting the engine will be replaced with some half inch steel stock as well as spacers under the rubber to gain clearance for a 4 in. steel flywheel. The heavier steel also bringing the center of gravity down.



The taper collet lock on to the crankshaft is used, So to draw the flywheel off the collet for removal, a pair of 8-32 screws into the frame will pop flywheel off when servicing.



Cutting in the taper. I set the compound to 7 Deg. and have at it. The collets used are Delrin with a single split cut across. I like brass or leaded steel here over C.I. or C.R. on these large parts and the Mini Mill and Lathe appreciate the ease of cutting these materials too!   

[Longboy]

The lower end completed. With five bolts the 4x4 top end attaches and I can figure out the valve block spacing to the heads.



The cylinder heads in a 3/6 head bolt line up with the crank.      My thought at the start is the head ports would be at a right angle to the engine length with some offset from the head bolt at 90 degrees on the intake side. That would be impossible with the ex. valve block porting facing the heads and joined by a tube with its fittings to the head..........the valve block would end up another inch away from its mounting to the 4x4 vertical side. That is a distance by scale here not acceptable.   



The solution was to rotate the heads around 30 degrees. Re-drill the head mounting to the cylinder collars on the top. The porting can now be centered between the head bolts each side. The ex. valve block ports can be reversed, facing to the outside of the engine.



With some longer curved tubing and 90 deg. fittings to the valve block......that integration into the head ex. port is completed! The valve block can reside close to the frame now with the tubing coming over its top.

[Longboy]

Over onto the intake side, a set of individual valve blocks bolt to the intake ports of the heads. A short tube into the head and v-block with an O-ring seal around tube.



A piece of painters tape make a good gasket here. I got a whole roll of this stuff so when I build a fleet of four valve V-12 engines   .......it should last me! Four 2-56 screws join the halves.



Will I need a five inch long piece of Delrin to mate the carb to the valve blocks here......or sumtin else?   



The fittings on the Ex. side tubing are not hardware store items. Made from 3/8 in brass hex, they are threaded 1/4- 28 into the ports and 5/16-24, male to female nuts. Tubing is 5/32 in. K&S products. A plumbers O-ring over the tube into the nut makes the seal and proves the concept of remote valve blocks for the hot exhaust side of the engine.   

[Roger B]

An interesting design     

The pipes linking the cylinders to the exhaust valve seem quite small for a 1" bore engine 

[Longboy]

Looks like a shorty block of Delrin for the carb and then continuing the theme and continuity of tubing from the manifold to the In. valve blocks. A short post extension and couple of 4-40 screws ties the manifold block to the outside corner of the 4x4.



Now I can work the camshaft position under the Ex. valve block with the bracket spacing and ignition parts as well a drill the heads for spark plugs.



The basic distributor body and eighth inch angle bracket to the 4x4 heading for the front end of camshaft.

[Longboy]

Upon a couple of eighth inch aluminum angle pieces, the camshaft with drive sprocket and guard on the left and distributor and point set on right. Rotates on a pair of brass bushings. Valve spring retainers as lifters ride the cam lobes. They are threaded to the valve stems and adjust to needed clearances. Cam lobes are created from 3/8 leaded steel rounds. Machine faced and hand filed profile finished. On the bottom plate of the valve block, the exhaust ports into the valve guide drilled and tapped at an angle for some straight pipes to come.



And on the top, some baby blue wiring from the PVC dist. cap to the spark plugs in a uniform pathway.


   
       The engine is finished! Time to disassemble for paint and polish. Loctite some important fasteners. Do the static valve clearance and timing as well as same for ignition spark. Make a fuel tank and plumb up to some kind of carb. Mount flywheel and nose damper after re-assembly. Then see how much grief it will give me in getting to idle along till the tank runs dry without any parts rattling off!     

[Longboy]

Satin black on the 4x4 and the shoe bars.



Will highlight the heads and cylinders well.



Leaving all other parts natural polished. The two slots between the cylinders on vertical leg of the 4x4 an aid to airflow as the frame somewhat shields the cylinders. May follow up at a later date with a fan set-up.




THREE BELOW had a short set-up and troubleshooting period. Using an OS carb and will start by hand with its low compression. See you soon for the presentation!      .....Dave

[Longboy]

  Welcome to the premier of my latest model.



Longboy's 'THREE BELOW" 3 cyl. gas engine.



The THREE BELOW build was started last week of October.



And completed 3rd week of January.



OS .15 carb, CM-6 NGK plugs. 1x 1.125 Bore & Stroke. 4 inch flywheel. 3.6 OZ. fuel tank.



20/40 MXL cog cam drive. Tecumseh points & condenser.



Special features: Cross flow ported flat head. Direct mount intake valve block. Remote above cam exhaust valve block......



........Tube feed carb to intake v-block. Tube discharge to exhaust v-block. Under deck cylinder mounting, lower profile stance.
900RPM range low idle speed. Weight 13.6 lbs.

See it now and thanks for following the build!      Dave.

<a href="https://www.youtube.com/watch?v=h0E6qiK6wTQ" target="_blank">http://www.youtube.com/watch?v=h0E6qiK6wTQ</a>