4 cylinder inline aero engine

[fourstroke]

Hi everyone

This is my fourth attempt at uploading some pics of my latest engine
I have set the camera to its lowest setting and took new pics so fingers crossed it works

The bore and stroke are 21 x 20mm and it has been cut from bar stock
The bad news is all the previous pics of the construction up to date are too big so I cant add them to later posts

Regards

Dougie

[Niels Abildgaard]

Very impressive.
Do You have  some pictures of crankshaft/camshaft manufacture?
Can it run upside down?
Your  work deserves better resolution pictures than what is allowed here.
If You upload them to for example Imgur and give the link,we can see it very much closer.

As example:

http://i.imgur.com/4FQRZlJ.jpg

[kuhncw]

Dougie,

Very nice looking engine.  I really like the exhaust piping.  Looking forward to hearing it run.

Chuck

[kuhncw]

Hi Again Dougie,

What is the status of the open column twin you were building?

Chuck

[Brendon M]

...
The bad news is all the previous pics of the construction up to date are too big so I cant add them to later posts

Regards

Dougie

Hello Dougie,

I use a bulk photo processor known as NConvert

I place all the pictures want resized into a folder and (assuming nconvert.exe is in the same folder), execute the following commands:

mkdir processed
nconvert -out jpeg -resize 800 0 -ratio -o processed\% *.jpg

Where "-resize 800 0 -ratio" resizes the images to 800x600. If I remember correctly, 1024x768 is the max display size for attached images on this forum.

This command also puts the resized images into the sub folder "processed", leaving the original images unaltered.

[fourstroke]

Hi everyone and thanks for the replies

Chuck,
The twin cylinder came to an abrupt halt when it cut the top of my finger off while I was messing with it.
The resultant few weeks of inactivity is where the idea for this engine started and it pushed its way to the front of the queue
I will get it finished this year but I think I may simplify the ignition system, I saw a post on HMEM where someone had a wasted spark system on a twin so I will ask for advice
There are a couple of pics of that engine, as it stands today, at the end of the post.

Niels and Brendon,
I will look into ways of resizing my pics but I will require the help of my tame teenage computer wizz.
To be honest I am less than impressed with the photo allowances on this site.
The crankshaft is built up with loctite and pinned, thats how I do all my cranks, if I get my pics sorted I will post
The camshaft hasnt been assembled yet, I'm still waiting for the bearings but the individual cam pairs have been filed and will be located on the shaft with loctite in the manner described in the "vega" v twin

Regards

Dougie

[cwelkie]

Very nice Dougie!
Let's hope this one doesn't claim any body parts ...
I'm curious about the ignition - seems you've separated the ignition timing and switching (hall effect/points) from the HT distributor.  True story?  Always interested in how model distributor designs work out ... currently puzzling over one for my 1/4 Cirrus.
I hope you get the "photo thing" sorted out.
Charlie

[fourstroke]

Hi Charlie

These are my thoughts and feel free to jump in if I'm way off target

I have a little ignition box I built with the circuit designed by jgedde that has a small coil from ebay providing the spark
The circuit will be triggered by a hall sensor, 4 magnets spaced around the timing disc inside the dummy mag. The spark will then be directed to the correct cylinder via the dristributor.
This might make more sense if I was able to post some pics but any advice is always welcome

Regards

Dougie

[fourstroke]

Hi

I think I got the pictures resized thanks to my son so here go's with a description of what I did to get to where I am

The first couple of pics show a block of 2.5" sq aluminium of undetermined parentage that has been lying around my shop for years, it was cut to size and split lengthways in the band saw before being milled square. The two halves were milled on the edges to make the flanges for bolting the two together
The base was set at an angle in the vise and hollowed out. Before any hollowing was done on the top the gear train centres were marked on the end, set up in the 4 jaw and the 10mm hole for the camshaft drilled and reamed, the camshaft will run in 5, 10x4x3mm bearings. Ignore the word "front" on the end of the piece, I did and it subsequently became "the back"

The last pic in this section shows the cylinder holes being bored, at this point the top section has been hollowed leaving the bearing sections, it was then set square on an angle plate on the mill and the main bearing holes bored but I dont have any pictures of that setup

If this works, more to follow in another post

Dougie

[Zephyrin]

Wow, Beautiful engines, both of them ! congratulations!
are we allowed to see the innards of the delco of the inline 4, and the box on its side, the contact breaker ?

[fourstroke]

So that worked, lets charge on

The top was marked out and drilled for the tappet guides and 4 access holes were milled in the side , these are to allow me to position the cams on the shaft later at the correct TDC position, this method was used by David Parker on his vega  v twin and it has served me well

The split bearings were made by soldering the halves together and drilling and reaming to size. This was then glued to a mandrell, turned to size, and the three sections parted off before melting the solder to split them

The third pic shows one of the cylinders which has been bored and mounted on a mandrel to finish the outside. These were then transferred to the mill rotary table mounted vertically, again on a mandrel, for the flats to be cut into them, two flats on the middle two and one flat on the outer two. I had to pay attention at this point, remember the front and back episode in my last post?

Next shows the fins being cut, a 0.8mm slitting saw made short work of this job, one I had been thinking of doing in the lathe with a parting tool, I'm glad I did'nt

The cylinders were then chemically blackened to give them a bit of contrast

more pics to follow

Regards

Dougie

[fourstroke]

I'm sorry if this build log is a bit disjointed but I hadn't really planned to document it and I dont have as many pictures as normal

The next set of pics start with the cylinder head. This is made from a block of 25x40 aluminium. The top was marked with the hold down holes, valve guides and rocker post positions while the underside had the cylinder centres marked on it

This was mounted on the lathe faceplate and each combustion chamber bored to size and depth, 8mm. The raised portion on top of the clinder is 3mm high and is the register and will provide the head seal, I plan for the pistons to reach level with the top of the cylinder leaving a compression space of 5mm
All the holes on the top face were counterbored to allow the finning to continue interupted along the length of the head.

At this point I should say that my inspiration for this engine were the various "cirrus" models and as the head progresses it will be apparent, I had some help with details of the Zimmerman and Whittle heads from a couple of contributors, thankyou.

The block was then milled to give the impression it is 4 seperate heads a la cirrus, the spark plug holes were drilled and counterbored and the edges rounded. I next made the valve guides and before I secured them with loctite, I set the head on an angle plate to let me cut the fins on the top, the middle 6 are spaced at 1mm and the outer ones at 1.2mm. Two sacrificial bolts through a couple of the valve guide holes held it in place
The final pic shows the head set up in the mill vise to cut the horizontal fins. I secured it to a scrap of steel through some of the holding down stud holes using long 6BA screws, this let me cut all the way around at one setting with the 1.2mm slitting saw

A couple of plugs were cut to fit the outer two holes in the head and the top half of the crankcase, this let me transfer the holding down stud holes from the head to the crankcase and ensure everything was straight

Regards

Dougie

[fourstroke]

This next set of pictures show how I made the rocker posts and the rockers themselves

The posts are made from 5mm stainless and the cross piece from 5/32" stainless
I faced the posts to length then made a little jig to hold each piece in turn in the mill vise so that the cutouts for the cross piece would be in the same position. The cross pieces were drilled through 2.5mm before both pieces were masked with tipex, fluxed, wired together and silver soldered

The rockers are next, I didn't relish the idea of making 8 individual rockers so the pictures show what I came up with. I first drilled the hole for the shaft then milled the profile into a piece of 3/4" x 1/4" steel. Next I set it up in the mill and used a slitting saw to cut the bar into the individual pieces, I had to do this twice, three times actually, as I wasnt happy with one of the sets
Once these had been seperated the end was marked, drilled and tapped for an 8BA screw which will be the tappet adjuster
The rocker posts had been cleaned of flux in my acid pickle and once washed they were drilled through 6BA clear in the lathe

As always, comments or suggestions are welcome

Regards

Dougie

[fourstroke]

Zephyrin asked about the internals so here are some pics

The first pic is of one of the conrods, 4mm little end and 8mm split big end. The shape was cut by mounting the rods on a spigot in the mill and taking light cuts while turning the rods by hand
Next is the crankshaft with the rods attatched, the shaft is made by loctiting the webs and crankpins to the central part, once the glue sets the webs are pinned to the centre and crankpins before the unwanted portions are cut out with a hacksaw, this was then held in the mill vise and the ragged portions between the webs milled flush

The third pic is the upper crankcase with the shaft fitted to the three internal bearings.
Sorry I dont have more detailed pics

Dougie

[b.lindsey]

Glad you got the pictures sorted out Dougie, Beautiful engine!!

Bill