4 Cylinder Inline Engine

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Well it's been 26 days since I finished my 4 cyl boxer engine and I am having withdrawal jitters so time for another engine build. This one will be a 4 cly inline overhead valve engine with an all ball bearing crankshaft, mains and rods.

I got this chunk of aluminum the last time I went to my metal supplier so it will determine the starting size.
First surface the top and bottom.
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The engine will be air cooled so I cut some cooling fins on each side. I don't think I went deep enough with the fins so I will redo that at a later time.
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A few pictures of the size.
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Thanks for looking
Ray
 
What design are you working with?
 
I am not sure I understand your question gbritnell.
I have seen round crankshafts pressed together and then drilled and locked in place. Rotax comes to mind.

Bored out the 4 cylinders for the cast iron liners.
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I have been corralled by the wife to remodel our kitchen and dining room.
Progress on the engine will slow down drastically.

Thanks for looking
Ray
 
Did you design the engine or are you working from someone's plans?
 
I understand now thank you for asking.
I make it up as I go along.
Sometimes that's good and sometimes I have to start over but always the engine runs in the end.

Ray
Best to do some drawings.
Positioning of holes become paramount especially with 4 cylinders.
.......and there are plenty which you do not want to intersect.
......and then there are those which must end up in the correct place starting from some obscure angle.

 
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Got some more done on the engine starting with the cast iron cylinder liners.
Two of the chunks in the back make 4 liners.
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After clamping the liners overnight for the sealing to cure I decked the engine block.
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I opened up both sides of the block to get some rod clearance but I didn't have to go that far.
I just like to see the moving parts when possible.
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Thanks for looking
Ray
 
The kitchen remodel project is winding down and I have gotten some time to work in the shop again.
I will try to build a crankshaft with needle bearings on the connecting rod journals. To do this I can't use any type of sealant on the crank assembly like LocTite as it may migrate into the bearings and that would be bad. All pieces will be a press fit only.
Wish me luck.
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Thanks for looking
Ray
 
The kitchen remodel project is winding down and I have gotten some time to work in the shop again.
I will try to build a crankshaft with needle bearings on the connecting rod journals. To do this I can't use any type of sealant on the crank assembly like LocTite as it may migrate into the bearings and that would be bad. All pieces will be a press fit only.
Wish me luck.
View attachment 154610

Thanks for looking
Ray
I've long wondered about the issues of doing this with a multi cylinder crankshaft. I guess you'll have to make some kind of alignment jig for pressing the sections together?
 
The center rod in the picture is 8mm and is a close sliding fit through the sections. Great care will be taken to drill the offset throw holes as straight through each section as possible. Even a few thousands off will cause many problems. The rod journals will be made from 9mm drill rod with each end reduced to around 0.322 for a length of 0.625. This will give me a stop to press into each section with the bearing in the middle. I plan on starting in the center of the crankshaft and working our each way. If I come to a section where the center rod can not be slid through easily then that needs to be addressed before continuing.
I hope to have time tomorrow to test my ideas.

Ray
 
The kitchen remodel project is winding down and I have gotten some time to work in the shop again.
I will try to build a crankshaft with needle bearings on the connecting rod journals. To do this I can't use any type of sealant on the crank assembly like LocTite as it may migrate into the bearings and that would be bad. All pieces will be a press fit only.
Wish me luck.
Ray, take a look at Graphogen-
https://www.graphogen.co.uk/index.asp?pageid=644920
We used to use it a lot when assembling our old british bike engines in much younger days. Coat the bearings and bores with it before assembly and the loctite won't be a problem.
But don't do what a friend did, he thought he could just substitute graphite grease for it- wouldn't listen to us- much cheaper and just the same he said- wrote off his engine in the first minute of the first start!
Ken.
 
Thanks Ken I will keep that in mind.

I fully intended to document the assembly of the crankshaft but in the heat of things I completely forgot.
Clocking the sections was not a problem even when the outer two sections were added and the center rod was removed. These sections do not have a center rod for alignment so I pressed one end section on only about a 1/4" and then took it over to the lathe. The outer section and the next section were then clamped tightly in the 3 jaw chuck and that brought both sections into alignment. Then back to the press to finish the press the rest of the way.
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Quite happy with the crank so far.

I cut out two bearing caps on the CNC.
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Right off the mill.
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And installed on the block.
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Thanks for looking
Ray
 
I muddled over how to line bore the main bearing caps for some time with the equipment and tooling I had and finally decided on this setup.
I know it looks sketchy but it was quite stable and at at 65 rpms it worked fine.
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My 3/4" drill bit was just long enough to reach through both ends.
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I did have to flip the block around and realign it as my big boring bar was too short to reach.
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The results were very satisfactory with a nice smooth turning crankshaft in the end.
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Thanks for looking
Ray
 
I thought about it before I milled out the center section of the block but decided against it. The compression ratio will be 6 to 1 with a 1" stroke and don't expect the rpms to exceed more than 2500. I like slow running engines. If it proves necessary I can cut the crank in half and add another bearing and add a block to mount it to.
Thanks for the comment.

I machined 4 connecting rods on the CNC today but it took me twice as long as it should. There was a power glitch that spoiled one of the rods and I had a couple of senior moments but I got the job done.
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Made some slots for the rod bolts to set in and then halted machining for the day.
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One last thing I wanted to get some paint on the crankshaft before it started to rust.
Looks pretty nice.
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Thanks for looking
Ray
 

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