Let's make a 4 cylinder flat

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Location
Weirsdale, Florida
I have never built an engine with more than 2 cylinders before but I was really impressed with how smoothly my last engine the "Horizontal Twin" ran that I am going to try a 4 cyl version. I want to use three ball bearings on the crank shaft so that means I will have to make a built up crank. Now I haven't had a lot of luck with built up crankshafts in the past in fact I dread making them so maybe I need a different approach.

I started by carefully making the webs all the same length, thickness and width except for the outside two they are thicker. I drilled all the holes on the mill using the DROs so I could could get them all the same spacing and in the correct location.
IMG_2639.JPG

The holes were sized for a close slip fit so I need a way to hold the webs at exactly a 90 degree angle to the main shaft.
I put the main shaft in the lathe chuck at the desired length for the first web. Using a lot of Loc-tite 620 I held the web against the chuck jaws using the tail stock and a socket.
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After about 15 minutes I removed it from the chuck and this is the result.
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I also glued some of the rod journals before assembly using the same method.
IMG_2646.JPG

I reinstalled the main shaft with the long end sticking out this time and started adding pieces.
I cut 10 spacer blocks to insert between the webs as each new piece is added and no I didn't forget to put in the center bearing.
IMG_2650.JPG
This was all held in place overnight to allow the glue to really set up.
All the joints were drilled and tapered dowel pins installed before cutting out the main shaft spaces and trimming the rod journals.
Here it is after filing off the dowel pins and a little more cleanup.
IMG_2652.JPG

It looks to be fairly straight but the real test will be when it is installed in the engine block.
Fingers crossed.
Thanks for looking
Ray
 
The crankshaft is very nice.
Please update !
 
Thanks Minh but I don't know yet how it will work out. It may be as crooked as a cork screw.

Cut and assembled the main frame for the engine. I am using some thinner stock for this engine as I think I overdid it on the "Flat Twin". The side rails are 1/4", the end rails are 1/2" and the center support is 3/8".
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This shows milling out for the main bearing caps.
IMG_2659.JPG
Main bearing caps installed.
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Next will be line boring the main bearings.

Thanks for looking
Ray
 
Are you going to do the “front/back” timing belt again or attempt to get it all in the front “Subaru style”?
 
I will do two timing belts like I did before as I have a good supply of belts and sprockets that didn't fit the twin.
4 cylinder
overhead cams
0.750 Bore
1.100 Stroke (don't ask how I came up with that)
4" flywheel
I want to make a distributor of some kind to simplify the build and save money.
Thanks for the question.

Indicated the block in the four jaw and drilled a 1" hole all the way through.
IMG_2665.JPG

Using my biggest and longest boring bar I finished the hole out to size for the bearings.
IMG_2668.JPG

I installed the crankshaft and was surprised to find it turned smoothly. I was expecting the shaft to be bound up or at least notchy but it's not. No straightening necessary and both ends run true.
IMG_2672.JPG

Some times you just get lucky I guess.
Thanks for looking
Ray
 
I did some more cleanup on the crankshaft and gave it a coat of paint.
IMG_2675.JPG

Drilling of the cylinder base bolt hole circles and access holes.
IMG_2677.JPG

The crankshaft paint turned out so nice I thought I would paint the main block too. I put a wood dowel through the main bearing blocks to keep this area clear of paint and a way to hold the block.
I chose Allis Chalmers orange for a good color contrast.
IMG_2679.JPG

That's all for a while as I am leaving today on a 7 day cruise.
The paint should be well cured by the time I get back.

Thanks for looking
Ray
 
Well I am back from the cruise but not in too good a shape yet. I never got off the ship and spent most of my time in my room.

The paint is dry and it turned out great.
IMG_2684.JPG

I will probably start on the cylinders in the next couple of days but it depends on how I feel.
Thanks for looking
Ray
 
Grasshopper I usually just build as I go long. I do make a few drawings for use in the shop but they wouldn't be of much use to anyone else. Why don't you take a vacation to Florida and stop by the shop. You can take all the measurements and pictures that you like. Visitors welcome

Busy day today as I got all four cylinders roughed out.
IMG_2704.JPG

Drill some holes tomorrow.

Thanks for looking
Ray
 
My wife and I were driving through Florida one time, and saw a sign on the side of the road "Boiled Peanuts".
I thought "those may be good", so we stopped and bought some.
LOL, I can't say as I would recommend them; the mush texture was just too much.

Must be an acquired taste.

Great build thread !
Thanks for posting it.

.
 
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You are so right Green Twin I can't stomach them either. They are very popular and many stands around to sell them.
It's like "chestnuts roasting on an open fire" sounds so delicious so I tried them once when I was in Italy. I couldn't spit them out soon enough.

Thanks

Ray
 
Back to the build.
I marked the hole locations on the mill using the DROs and drilled the holes on the drill press.
IMG_2709.JPG

Next back to the lathe for some cooling fins and a little shine up.
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Looking great in their Sunday best shine.
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Happy dance the holes all lined up.
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I also taped the head bolt holes. The cylinders should now be completely done.

Thanks for looking
Ray
 
Drilled the holes in the connecting rod ends and they even ended up in the right place.
IMG_2727.JPG

Then I cut the ends off at the crank bearing center line with a little hand saw. There must be a better way but I persevered.
Enlarged the holes in the rod end caps for some #4 screws.
Threaded the rod holes 4 X 40 and didn't break a single drill bit or tap.
I made some brass bushings for the piston end of the rods and pressed them into place.
It doesn't look like much was done but when you are doing 4 of them it takes some time.

IMG_2733.JPG


Next will be the crank shaft rod bushings.

Thanks for looking
Ray
 
I am going to try something I have never done before but I have seen other builders talk about it and have seen the results so why not give it a try.
I have always made my rod bushings for the crankshaft end from round stock and sawed them in half or close to in half as I could so they would fit around the crank journals. This leaves things a little less than desired where the half's come together and the halfs are not always the same size.
So here goes.
I started with a couple of pieces of hard brass 0.312 in thickness and about the same size.
IMG_2736.JPG

Over to the mill to square them up and make them the same size in height and width. This gives me a 0.625 square piece about 2" long with a split going down the center.
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I then sanded the mating sides and super glued them together.
After 5 minutes it was over to the 4 jaw and I dialed them in to run as true as possible.
IMG_2742.JPG

I turned the outside diameter round and it ended up about 0.610 which was fine.
Using a parting tool I cut the flanges for the depth and width of the connecting rod and started on the center hole.
I was afraid the two halfs would split apart when I started drilling the center hole for the rod journal but that didn't happen. Things went remarkably well with no problems.
Back to the parting tool to finish cutting the bushings off. I made two bushings at a time in case this didn't work I wouldn't waste too much material on my first try.
IMG_2743.JPG


Here are the first two right off the lathe.
IMG_2746.JPG

And installed in the connecting rods.
IMG_2749.JPG

The first two bushings took me over 3 hours to make but the second two took only about 45 minutes.
This is a much neater and a more accurate way of making rod bushings so here they are all installed..
IMG_2751.JPG


Thanks for looking
Ray
 
I am going to try something I have never done before but I have seen other builders talk about it and have seen the results so why not give it a try.


I turned the outside diameter round and it ended up about 0.610 which was fine.
Using a parting tool I cut the flanges for the depth and width of the connecting rod and started on the center hole.
I was afraid the two halfs would split apart when I started drilling the center hole for the rod journal but that didn't happen. Things went remarkably well with no problems.

View attachment 152643


Here are the first two right off the lathe.
View attachment 152644




Thanks for looking
Ray

I usually turn the workpiece close to the OD ,drill the center hole close to size, finish the outside and then finish the inside diameter
But anyway, you succeeded 👍
 
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I did some more cleanup on the crankshaft and gave it a coat of paint.
View attachment 152166

Drilling of the cylinder base bolt hole circles and access holes.
View attachment 152167

The crankshaft paint turned out so nice I thought I would paint the main block too. I put a wood dowel through the main bearing blocks to keep this area clear of paint and a way to hold the block.
I chose Allis Chalmers orange for a good color contrast.
View attachment 152168

That's all for a while as I am leaving today on a 7 day cruise.
The paint should be well cured by the time I get back.

Thanks for looking
Ray
When I saw this, I thought "that thing is huge!"
I wan't to try a built up crankshaft but need to wait until I have a grinder to get the last 40 thou of runout off when I'm done. Hats off to those skilled people who can do these things.
 
I worked on the pistons today but forgot to take most pictures.
I did take this one showing drilling the hole in the piston for the wrist pin.
I had already bored out the inside of the piston for the connecting rod end.
IMG_2753.JPG

One piston and rod assembly next to a bic lighter shown for size comparison. (this one is for you Jonathon)
IMG_2758.JPG
All four pistons are mounted on the rods and installed in the engine.
There were no interference problems.

Thanks for looking
Ray
 
I changed the order of the build so I could first install the front cog belt pulley and make sure it ran true. Then I decided to make up the flywheel so it would be easier to turn the engine over after installing the o-rings.
I had an ugly piece of 4" round steel that I had tried to use on a different model a couple of years ago for a flywheel but it wasn't big enough for that model I think it may just work fine here.

I started by digging out 0.200 from both faces to thin it down on the lathe.
IMG_2766.JPG

Then over to the mill to make some lightening holes to improve the looks.
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The center flange was from a previous build also and required the center hole to be enlarged to fit this crankshaft.
Painted both pieces and left them to dry overnight.
Installed the belt pulley and the flywheel today.
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What do you think?
Should the center taper lock flange be a different color?
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This shows how I cut the grooves in the pistons for the o-rings.
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Pleased to say all cylinders hold a vacuum for at least 30 seconds.

Thanks for looking
Ray
 

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