Straight 6 Cylinder Engine

Rdean33422 · Jun 7, 2024

After sawing through the bushings and rod caps I will enlarge the rod cap bolt holes to fit the size 40 screw and tap the rod holes 4-40. Now when I reassembly the rod caps there is an egg shape on the inside of the bushing but the inside of the bushing needs to be reamed out to 7mm and that makes the hole round again and on size for the crank throw.
Thanks for asking
Ray

Rdean33422 · Jun 8, 2024

I spent most of today drilling, taping, sawing, and reaming the rod ends.
I was rewarded with this.

And everything fit !!

Thanks for looking
Ray

Rdean33422 · Jun 9, 2024

Turned out 6 pistons but forgot to get a picture.
This is the setup I used for the rod end slot 0.750 deep.

I installed brass bushings in the rod ends for the wrist pins.
All six done and ready for the wrist pin holes but not today.

Thanks for looking
Ray

Rdean33422 · Jun 10, 2024

Very hot in the shop so a short day.
Drilled the holes for the wrist pins.

They all fit nicely

Thanks for looking
Ray

Rdean33422 · Jun 11, 2024

Since things are fitting properly so far I thought it would be a good time to spot drill the block for the head bolts.

Then over to the drill press to finish drilling the holes to depth.

Then tap 24 holes 6-32 and glad to report all went well.
I was sweating that last hole as that's when the tap usually breaks off but not this time.

Thanks for looking
Ray

Rdean33422 · Jun 12, 2024

I am kind of straying off course but I thought this would be a good time to see if i could make a cylinder head from the piece cut off earlier. If you remember I stood the 12" long piece straight up in the band saw and it cut straight and true. So why not try it again and cut off a 5/16 thick piece. That should leave me just over 1" thick by 2.5" part 11.5" long for the cylinder head.

It worked out great with a 0.045 difference in thickness from top to bottom.
I trued that up on the mill and then cut another 1/2" off the width the same way to get to 2" wide. Sorry no pictures.

These are the two finished pieces.

Over to the CNC to spot the twenty four holes for the head bolts and the intake, exhaust valves, and the spark plugs.

Back to the drill press to finish drilling the head bolt holes.

Now for the real test I have 24 holes drilled and taped in the cylinder block 11.5" long. I have 24 holes drilled in the cylinder head and all the holes were drilled on a bench top drill press. A couple of thousands off on each hole times 48 and the bolts won't fit.

I was very pleaded that all the holes matched and the bolts went in without interference.
That is a mile stone for this project.

Thanks for looking
Ray

ShopShoe · Jun 13, 2024

Ray,

Congratulations on the excellent fit, especially considering the drill press. You have demonstrated that careful attention to detail can work wonders.

As a friend of mine used to like to say:

"You must have held your mouth just right for that to work out"

--ShopShoe

Rdean33422 · Jun 13, 2024

ShopShoe said:
"You must have held your mouth just right for that to work out"

Yes and the moon was in the right phase too.

Time to get this engine to stand up on it's own. I have thought about this for some time and drew up a couple motor mount designs but I didn't care for them . In the end I will go with the same type I used on my 4 cylinder engine only a little smaller in size.
This is a block of aluminum that was left over from my radial engine build.
Milling away the parts that don't look like a motor mount.

Here they are mounted on the engine.

I also made some risers to gain enough height for the flywheel.

I was thinking about naming the engine maybe Six Pack, or Six Shooter, but I am open to suggestions please.

Thanks for looking
Ray

xander janssen · Jun 14, 2024

Great engine. Looking forward to the first time running.

Are you running it without piston rings? I know engines (also one of my own) that run without rings, but there the pistons have a very tight fit in the cylinders (0.02 mm or less). This dictates that the thermal expansion of the piston has to be same as that of the cylinder i.e. both made of the same material.

With aluminium pistons in a steel cylinder, I do not see how that can be done without either low compression at low temperature or seizure at high temperature.

Rdean33422 · Jun 14, 2024

xander janssen said:
Are you running it without piston rings?

No I will be adding o-rings later on.
Thanks for the reply.

Ray

Rdean33422 · Jun 14, 2024

In January of 2022 I finished a twin engine called Two Timer. This was the only engine that I built that had an active water cooling system.

It worked very nicely and kept the engine temp down on long runs. But I have only ran the engine with water in it 6 times since it was completed as the water pump shaft would leak coolant and make a mess. I try to run all my engines at least once a month and then for only about 5min each so a water cooling system is not necessary. I will be using this water pump and radiator on this build and hope to be able to keep the cooling system intact and not have to drain it each time.

A couple of pictures from 2022 so you can see the insides.

I have modified the pump housing and added an o-ring to hopefully stop the shaft leak problem.
Here it is mounted on the engine.

Thanks for looking
Ray

Rdean33422 · Jun 16, 2024

I thought I would give the engine a name.

I am going to try and enhance the name so it shows up better.
Do you have any ideas?

So anyway I cut out the side plate and a gasket for it. I want to test the water pump before I go much further for flow and leaking.
Two things I need to change are the drive pulley should be larger to increase flow and the brass nipples ID should be enlarged.
This is the setup I am using to check for leaks.

Every time I think of it I run the drill for some time to circulate the water.
So far no leaks anywhere but I will leave this together overnight before making any of the other changes.

Thanks for looking
Ray

Rdean33422 · Jun 17, 2024

I made a new lower pulley to speed up the water pump and enlarged the diameter of the in and out brass nipples today. It did help but not as much as I had hoped. The water pump inlet port may be too small and I want to make a way to vent the cylinder cavity of any trapped air maybe tomorrow.

I finished drilling the rest of the holes in the cylinder head except for the spark plugs. I will drill them after the valves are seated.

Gave it a little shine.

Thanks for looking.
Ray

bluejets · Jun 17, 2024

Rdean33422 said:
I am going to try and enhance the name so it shows up better.
Do you have any ideas?

Etch with ferric chloride ....but only a quick dip.

Rdean33422 · Jun 17, 2024

bluejets said:
Etch with ferric chloride

I have never done that but but that gave me an idea.
Thanks
Ray

mayhugh1 · Jun 18, 2024

I thought I would give the engine a name.

I am going to try and enhance the name so it shows up better.
Do you have any ideas?

I have luck filling in the text with a paint pen ...

Steamchick · Jun 18, 2024

I should try to enhance the name with shoe polish, or similar dyed wax product. The wax may fill the pore of the etched text - then polish off the shiny surface. - Try various stuff on a sample until you find something that works for you? - The etched surface may be too fine to hold the wax though.
As a motorcyclist back in the 1970s I always had black hands from dirty engine oily muck... It washed-off the raised parts of finger prints but not the deep grooves. But maybe that is a skin thing, not aluminium. My mate was a printer, and he had the same from the printer's ink, which was primarily used engine oil loaded with graphite!
Dark wood stain may work, usually and alcohol-based spirit dye.
K2

ShopShoe · Jun 18, 2024

There are several brands of paint sticks available that may work for you.

There used to be some sold specifically for remarking the engraved settings on camera lenses, but I don't have that information anymore.

I tried googling "paint for remarking camera lenses" and found some discussions on this topic.

McMaster-Carr lists the following:

https://www.mcmaster.com/products/paint-sticks/paint-crayons-for-recessed-characters/

--ShopShoe

Rdean33422 · Jun 18, 2024

I want to thank everyone that left suggestions on the lettering. I have done this before on dials and art work but I was just not deep enough into the aluminum to hold a color on this plate. I have resurfaced the plate and shined it up for now I will leave it like it is.
I enlarged the water pump inlet hole from 5/16" to 3/8"and drilled and taped for a vent hole as high up in the water jacket as possible.
Now I have good water flow at 750rpms much better.

13 valve guides, one for an extra just in case.

Thanks for looking
Ray

Rdean33422 · Jun 19, 2024

I installed the valve guides last night and today extended the intake and exhaust ports into the guides.
Then tapped them 5/16 X 24 threads.

I got a start on the valves themselves.

Thanks for looking
Ray

Straight 6 Cylinder Engine

Help Support Home Model Engine Machinist Forum:

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Senior Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Project of the Month Winner!!!

Well-Known Member

Senior Member

Well-Known Member

Well-Known Member

Similar threads

Join the conversation!

Join today and get all the highlights of this community direct to your inbox. It's FREE!