Straight 6 Cylinder Engine

[Rdean33422]

I forgot the picture all the valves completed from a few days back.

Progress the last couple of days was laping in the valves, making spring retainers, and cutting the springs to length. I also installed the piston O-rings.
Sorry I didn't get any pictures of those processes but here are the results.




I drilled, counter bored 7/16", and threaded for the 1/4" X 32 spark plugs.


I then installed the head and checked for compression.


My usual way to check is to spin the flywheel and if it bounces back before TDC then there is enough compression to at least get the engine running. That doesn't work very well when you have a small test flywheel and the resistance of 6 o-rings to over come. You just don't spin the flywheel by hand so I hooked up the hand drill. Doing one cylinder at a time I installed the spark plug and spun the engine over holding the exhaust valve open. Then release the valve and if the drill wants to jump out of your hand then that cylinder is good. All turned out fine.

Thanks for looking
Ray

 

[Lloyd-ss]

Ray, I have to say that this project is turning out incredibly well. The thought and detail are very nice, but what makes me chuckle a little is the casual way that you describe the work you are doing. The only stressful part I noticed was tapping all the holes in the top of the block. I think the block and the tap must have both sensed your calmness and followed along with the flow. Now, ........... sawing that tall block of aluminum standing up on end in that short vise would have gotten my heart rate going high enough for the machine to sense it ....... and crash. And I am normally a pretty calm person, LOL.
Again, all very nice.
Lloyd

 

[Rdean33422]

Lloyd that is very kind of you to say.
I did not expect the tall cut to result as good as it did so I tried it two more times and they turned out just as good.
Thank you
Ray

 

[minh-thanh]

Hi Ray !
I like the way you make the engine: everything seems simple and easy.

 

[Rdean33422]

Thanks Minh

Thought I would continue on the valve train so I cutout the cam supports and made a brass bushing for the cam belt drive pulley.
I installed needle bearings for a cleaner look in the cam supports.


Side view of the 3/8" cam shaft.


I had this timing belt left over from a previous build and had no expectations that it would be even kinda close but it is the exact length needed for this engine. I think the cam shaft may be a little too high and away from the exhaust valves but I won't know until I have made the cams. I can shave off some on the bottom of the supports if it is and use an idler on the belt.


And the other side.


Thanks for looking
Ray

 

[Lloyd-ss]

@Rdean33422 , Very nice. That timing belt fitting just right is an indication of how that extra 6 cyl crank will be "just right" some day.

I like the needle bearings. Compact and you use the shaft that you made as the inner race, correct? Is the outer race a pressed cup or a machined hard piece (that would come instead of the pressed cup)? Do you just put a squirt of oil on the needles when you run the engine?
Ray, thanks for sharing and answering.
Lloyd

 

[Rdean33422]

Thanks Lloyd
The needle bearing have a hard shell. I packed some grease in them before assembly but I will give them a squirt of oil when needed.

Had to mow the lawn today but I was able to get this made.


I cut 1" off of this rusty chunk and made a flywheel.
The inside is made of aluminum.


Thanks for looking.
Ray

 

[Rdean33422]

I am going to let the paint cure on the flywheel another day so I don't mess it up. Maybe tomorrow.

I cutout the six cams today but I didn't get any pictures.
This is an older picture showing how I make my cams on the CNC.


All lined up but not timed yet.


Earlier I had thought the cam supports were a little high and they were by 0.020 or so so I took 0.040 off all of them just to be sure. I ended up shimming the supports back up 0.025 to get the correct height. Well that move made it necessary to add a belt tightener but that was probably for the best as now I have a way to adjust the belt.


Thanks for looking
Ray

 

[Sparky_SC]

How are those valve keepers attached to the valves? It is great how the keepers don't interfere with the action of the cam lobe.

It appears that valve lash is obtained by careful machining or shaving a bit off the keepers, there is no adjustment, is that correct?

I know that some of the lawn mower engines accomplish valve lash by grinding a bit off the valve stem until the clearance is within spec.

Very nice work once again !

 

[Rdean33422]

The valves are threaded as are the keepers but not all the way through. The final height of the exhaust valve is adjusted by tapping the keeper a little bit deeper and then rechecking until I get the same height. I start with the shortest valve and make the others conform to that height.

Thanks for asking
Ray

 

[Rdean33422]

Things don't always go right!


If you look at the picture closely you can see the timing belt tensioner is on the other side.
On most of my models the flywheel is on the front of the engine and it turns clockwise. When I built the crank I set it up for the water pump to be the front of the engine. and that end would turn clockwise to be more in tune with automotive engines. Well I completely forgot about that until I was setting the cam lobes. Nothing was lining up the rods were in the wrong places.
I was turning the flywheel clockwise not counter clockwise.
I moved the timing belt tensioner over to the other side, turned the flywheel counter clockwise, and started setting the cams.
When I was finished I turned the engine over several times and then went back to check the cams. None of them were where I had set them. I checked that I had tightened the timing gears to their shafts and that was correct. Only one thing left the timing belt.
On closer examination the teeth on the belt were wider than on the other belts I checked. The spacing was correct at 0.200 but the belt didn't seat into the teeth of the gears. I noticed the belt was a different color so they may be some special belt.
I ordered the correct one but it will be about 2 weeks for delivery.

Just hit me now the water pump turns backwards!! Maybe I can give the belt a half turn.

Thanks for looking
Ray

 

[Lloyd-ss]

Things don't always go right!
View attachment 157732

If you look at the picture closely you can see the timing belt tensioner is on the other side.
On most of my models the flywheel is on the front of the engine and it turns clockwise. When I built the crank I set it up for the water pump to be the front of the engine. and that end would turn clockwise to be more in tune with automotive engines. Well I completely forgot about that until I was setting the cam lobes. Nothing was lining up the rods were in the wrong places.
I was turning the flywheel clockwise not counter clockwise.
I moved the timing belt tensioner over to the other side, turned the flywheel counter clockwise, and started setting the cams.
When I was finished I turned the engine over several times and then went back to check the cams. None of them were where I had set them. I checked that I had tightened the timing gears to their shafts and that was correct. Only one thing left the timing belt.
On closer examination the teeth on the belt were wider than on the other belts I checked. The spacing was correct at 0.200 but the belt didn't seat into the teeth of the gears. I noticed the belt was a different color so they may be some special belt.
I ordered the correct one but it will be about 2 weeks for delivery.

Just hit me now the water pump turns backwards!! Maybe I can give the belt a half turn.

Thanks for looking
Ray

Ray,
It is funny how one little change can snow ball into a succession of "adjustments." But that is where your experience comes into play. I have always believed that what separates the men from the boys is being able to solve such problems gracefully, and you are doing that.
I am not too sure about the half turn in the timing belt, LOL. I know you already have the belt on order, but I have used some 2-sided timing belts in the past and that could solve your problem.... maybe.
Lloyd

 

[Rdean33422]

I am not too sure about the half turn in the timing belt, LOL.

I should have put a smiley face after that comment.
Thanks Lloyd

I decided to just make a whole new water pump with the vanes curved the correct direction. The first one pumped water alright but may have been a little weak so I went bigger with the new one.

New versus old housing.


I also enlarged the outlet of the pump and the inlet on the side of the engine.


Really moves some water now.

Thanks for looking
Ray

 

[Sprocket]

Sounds like a good solution. Quite a lot bigger impeller too.
Doug

 

[Lloyd-ss]

I should have put a smiley face after that comment.
Thanks Lloyd

I decided to just make a whole new water pump with the vanes curved the correct direction. The first one pumped water alright but may have been a little weak so I went bigger with the new one.
View attachment 157789
New versus old housing.
View attachment 157787

I also enlarged the outlet of the pump and the inlet on the side of the engine.
View attachment 157788

Really moves some water now.

Thanks for looking
Ray

I could be mistaken but it seems like I read a lot more about model engines having inadequate cooling rather than too much cooling.
Is that a fair statement?
The diesel I am making will just have drilled passages in the head, plus a water jacket around the upper portion of the cylinder. I can see where having just a few drilled water passages in the head might be marginal after a few minutes of running. Little electronic temperature gauge sensors and displays are pretty cheap and might help avoid a problem, or at least make it possible to adjust water flow to hold a steady temperature.
Lloyd
Any thoughts?

 

[Rdean33422]

Sounds like a good solution. Quite a lot bigger impeller too.

Thanks Doug it has improved the water flow.

I could be mistaken but it seems like I read a lot more about model engines having inadequate cooling rather than too much cooling.

This is my first engine that I plan to have cooling water in the engine full time. I haven't worked out all the details yet tho. Thanks Lloyd

A lot of other thinks happening over the past few days but was able to get started on the distributor.
These are the main parts.


All assembled and tested.


Painted the dist cap black even if it does look brown in the picture.


Thanks for looking
Ray

 

[Rdean33422]

I cutout the distributor bracket from a solid piece of aluminum, painted, and installed it along with the dist gears.






Thanks for looking
Ray

 

[Lloyd-ss]

@Rdean33422 , I notice that you paint most items "as-you-go". That implies a certain confidence level in the final product. Everything I make is apart and together 1,000 times, adding an additional tapped hole or machining a clearance, or adding a bracket, and on and on. My paint would end up as a well-worn primer that was totally damaged and needed to be re-done. I have gotten used to taking apart and putting back together. Its kind of funny, but it builds a relationship between me and the engine (or project) where I can design new modifications or spot problems in my head while working on something totally unrelated. I then transfer the new "info" to cadd before incorporating into the "metal."
How does the paining of the parts relate to your confidence in the "finished design," since this is not your first multi cyl inline. Just curious.
Thanks, Lloyd

 

[Rdean33422]

Thanks Lloyd this is my 16th model engine and I find I am more careful when working on the engine when it looks good. That doesn't mean that I haven't had to repaint some parts and many touch ups with the brush.
Painting early encourages me to do a better job.

These are the main parts for the intake manifold.
The inside is also curved and matches the outside.


The completed intake system.


The carburetor is mounted in an updraft configuration.
This all worked very well on the 4 cylinder engine I recently completed so we will see how it does here.


Thanks for looking
Ray

 

[Rdean33422]

I got the new timing belt I ordered and installed it today. It has the same number of teeth and they are of the same distance apart as the original belt had but it could have been 2 teeth shorter. I just moved the belt tightener over to compensate.
I had two of the original belts and I tossed them both in the garbage. I still don't know what they are for but now they won't mess with me again.

This time when I set the valve timing everything worked as it should.


I then set the ignition timing and tested for spark using this plate.


All that worked out fine so I made up and installed the plug wires.
I also made three wire standoffs to support the longer plug wires.


Thanks for looking
Ray