4 Cylinder Inline Engine

[Rdean33422]

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.


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.


A few pictures of the size.






Thanks for looking
Ray

 

[Nerd1000]

How will you make the crankshaft?

 

[Rdean33422]

I am working on a round design like a press together motorcycle type but that's still to be determined.

Ray

 

[gbritnell]

What design are you working with?

 

[Rdean33422]

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.


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

 

[gbritnell]

Did you design the engine or are you working from someone's plans?

 

[Rdean33422]

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

 

[bluejets]

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.

 

[Rdean33422]

I was able to get some time over the last few days from my (she who must be obeyed) remodeling job to make a big mess and a cavity.
Most of the scarf is in the waste bin already.



Thanks for looking
Ray

 

[bluejets]

That last image raises many many questions......

 

[awake]

That would seem to be a lot of chips! Looking forward to seeing more.

 

[Rdean33422]

Got some more done on the engine starting with the cast iron cylinder liners.
Two of the chunks in the back make 4 liners.


After clamping the liners overnight for the sealing to cure I decked the engine block.


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.


Thanks for looking
Ray

 

[Rdean33422]

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.

Thanks for looking
Ray

 

[Nerd1000]

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?

 

[Rdean33422]

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

 

[vk7krj]

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.

 

[Rdean33422]

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.

Quite happy with the crank so far.

I cut out two bearing caps on the CNC.


Right off the mill.


And installed on the block.



Thanks for looking
Ray

 

[Rdean33422]

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.


My 3/4" drill bit was just long enough to reach through both ends.


I did have to flip the block around and realign it as my big boring bar was too short to reach.


The results were very satisfactory with a nice smooth turning crankshaft in the end.


Thanks for looking
Ray

 

[Nerd1000]

Not running a centre bearing?

 

[Rdean33422]

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.


Made some slots for the rod bolts to set in and then halted machining for the day.


One last thing I wanted to get some paint on the crankshaft before it started to rust.
Looks pretty nice.


Thanks for looking
Ray