new side valve engine fom home made castings

[fourstroke]

Hello again

I've made some progress on the engine so I thought I would share it with you, the pictures are a bit sparce as I got caried away machining and didnt take as many pictures as normal

I made a start on the gear train for the camshaft, first I turned a short shaft to fit through the main bearing with a 10mm section for the rear bearing and a stub of 1/4" dia for the crank gear, you can see it sticking through the casting on the first couple of pictures. I scribed a line along the centre of the gear side of the casing then spacing the gears with a bit of cigarette paper between each pair I used a close fitting shaft with a point turned on it to scribe the centre point. This was centred using a wiggler, drilled and reamed 5/32". Each gear was done individually to keep errors and play to a minimum. the next picture shows the three gears in train to check the movement

After the last gear was reamed the hole in the casting was opened up to 16mm and using my home made centre the back of the casting was centred, drilled and reamed 10mm. The centre line for the valve guide holes was marked out on the cylinder head at this stage also

The next job was the gear covers, the casting was held in the chuck using the chucking piece and the base turned level. The holes on the bolting bosses were marked and drilled then the tops skimmed level. I drilled and reamed the small boss 1/4" to fit on the stub shaft used to centre the gears, this let me line up the casting as best as possible knowing that the gear boss was central, the holes were spotted through drilled and tapped 7 BA

Bushes were turned for each side of the camshaft and another shaft with a centre turned on it made. The cover was screwed to the casting with the shafts in place and a centre punched onto the gear cover, this was removed centred and drilled.

The casings were then mounted on a mandrel and the chucking piece was turned to length and diameter, this was intended to take the holder for the hall sensor I plan to use for ignition, to allow ignition timing alterations. The magnet will be mounted on the periphery of a bush on the camshaft but today I have been pondering the addition of a dummy magneto, chain driven fom the shaft, which might hide some of the electrical gubbins. Anyway, the covers were reversed and a start made to hollowing them out, they were then transfered to the mill and the hollowing completed

Comments and/or suggestions appreciated

You're right Bob, the top two bosses are for mounting the fuel tank, nice job on the cad drawing

Dougie

 

[stevehuckss396]

Looks cool daddyo!

 

[fourstroke]

Hello again
I have some progress to share on this project, and a tale of woe
I found that, as cast, the cylinder head did not have enough clearance in the combustion chamber for the valves, no problem, I just mounted a burr in the drill and started to grind away the sides of the combustion chamber. Winging it and not paying enough attention resulted in the c**k up you see in the first picture. Look to the lower right of the casting, I cleverly ground too close to the stud hole, not satisfied with this,I did the same to the other one !!
This resulted in an afternoon re casting the heads and starting over

The next pics show the main casting set up to machine the valve guide holes
The casting was drilled and reamed and then the underside of the casting was spot faced to provide a flat seating for the valve springs, the option of running the mill in reverse came in handy and is the first time I have used this in the 17 years I have had the machine. The holes were opened up to 16mm to finish the job
The valve guides were turned from homemade bronze bar and fitted to the casting, the bushes for the tappets were turned and fitted at the same time, the valves were made from stainless steel, 5/32 shafts and a 14mm head, sorry for the lack of pics here but I got carried away and forgot to take any

The next set of pics show my method of making the cams, I want a 3mm lift. I always start by making a couple of filing buttons the size of the base circle and hardening them right out, next I make a master cam with the material sandwiched between the buttons, filed carefully to size, and again hardened right out.
The next pics show the blanks for the cams set up for filing, I cut away most of the waste with a hacksaw before filing to shape, the hardened buttons and master cam ensure that each cam turns out the same as the last. The last pic shows one of the finished cams after polishing with emery

Another post to follow with more pics of the progress
As always, comments or suggestions are always welcome
Dougie

 

[fourstroke]

More progress again

This time I have some pictures of the cylinder liner, piston, crank webs and crank follower

I started with a chunk of 45mm CI bar, rough turned to the OD of the main body and top lip. Lots of drilling and boring resulted in a big pile of pound notes in the form of cast iron dust, the next pic shows taking the final cut on the liner to leave a couple of thou' clearance for the sealant once its put into the casting for good. The finished part, along with the piston are shown next, again, sorry for the lack of pics of the piston being turned and milled

Next I made a start on the crank, I settled on a bore and stroke of 36x44mm. 10mm steel was cut to rough shape, the two pieces for the crank were glued together with superglue, marked out, clamped to the mill table and both parts drilled and reamed, first for the crankshaft hole, 1/2" and then indexed 22mm, drilled and reamed 10mm for the crank pin
The crank followers were machined individually, marked out for the central, gear driver shaft,both were drilled and reamed 10mm. The mill was indexed 17mm from this centre and a 5/16" slot cut for the crank pin
A finished pair of webs are shown in the next picture and the finished crankpin in the next. The 10mm crankpin was set up in a rotary table on the mill and the sides machined 180 deg apart to finish 8mm across the flats. I plan to harden the crankpin and case harden the slot
Thanks for reading to my ramblings
Regards
Dougie

 

[fourstroke]

Made some progress on the engine I wanted to share with those of you interested
I ran into a couple of problems along the way, first I discovered that the stroke of 44mm was too big, things kept bumping into one another inside the crankcase so I had a rethunk and remade the webs with a stroke of 40mm, this got the clearance I needed but I also had to add a weight to one of the webs to balance the conrod and piston weights, thats the first couple of pics.
The first con rod I made is shown next, it was drilled and reamed 10mm for the big end and 1/4" for the gudgeon pin, it was set up in the rotary table and the ends and middle section cut by turning the rod by hand, carefully

I had been going over the designs for the oil pump for a while in my head so I decided to make a start on this, after a few false starts the basis of the main body is shown in the next pic, I silver soldered the half round piece to a chunk of 10mm brass. A few, (lots) of milling and drilling operations later the finished, MK1, version is shown in the next few pics
The connecting link from the crank to the pump is shown in the last picture having the slots milled, the rest was done with files and emery

Enjoy, comment or advise.
Regards
Dougie

 

[bmac2]

Hi Dougie
Just wondering, the oil system on the Whippet is basically just splash it around enough and it’s got to leek in some ware. Well except on the follower where the holes don’t look like it lines up. I’m guessing about a 3/16 (4.7mm) stroke on the pump so am I safe to assume that there is no need for any bypass valve? I’m wondering just how the oil path is changed in your engine, and do you see any need to take it up to the gudgeon pin? Great build I’m really enjoying this. I’ve got a start (with a very small “s”) on my patterns put it was so much easier on the computer.

 

[fourstroke]

Hi Bob
I have been wondering myself whether to fit a bypasss valve or not.
The stroke of the pump is about 7mm near as I can measure from a 14mm offset at the crank
Even with a short stroke the engine may be turning around 6-700 rpm which is a lot of oil. I have designed the crankcase to hold a fair bit of oil so that the pump dosent run short due to the splash system but I am concerned that it might lock up and bend one of the connecting links if the pressure builds. All the bearings have oil grooves cut into them to give the oil somewhere to flow
My options are to fit a bypass or to tee one of the pump outlets and run an oil line to the top of the gear case allowing any excess pressure to vent there, this would also supply the gear train with oil
The pump was originally intended just for the main bearings, everything else was just splash, the gudgeon pin included, both main bearings also have oil collecting points cut into them as in the whippet, a bit of a belt and braces approach
Any thoughts or advice would be appreciated

Dougie

 

[charlesfitton]

Hi Dougie - really enjoy this build, thanks.

Just a thought here - for future plans you may have....

Seems to me that that the timing gear train could be worked into a very serviceable oil pump, if one were to think it through...

 

[fourstroke]

Your'e right Charles
Now Iv'e got something else to roll around my head. I mentioned earlier that my projects can keep morphing as I think of something else to add or fit
I have a long drive tonight and that little gem will keep the old grey matter active.
Dougie

 

[fourstroke]

I have been trying to think of something to call this engine and nothing I have come up with has taken my fancy
Can I ask for some suggestions from anyone reading this thread?
Regards
Dougie

 

[Charles Lamont]

I have been trying to think of something to call this engine and nothing I have come up with has taken my fancy
Can I ask for some suggestions from anyone reading this thread?

Well, it is pretty much an up-scaled Whippet, so Greyhound? Seems a bit overblown for a single-pot side-valve job, but you could always claim it was ironic.

 

[Mechanicboy]

Lever oil pump can break off in case overpressure in the lubrication system. Install a pressure relief valve as well in case it would be too high to lever snap off. I've never seen problem with splash lubrication in small 4-stroke engines found in Briggs and Stratton engines and they last long lifetime.

 

[Brian40]

Hi Dugie.
I have just read your thread about wanting a propane carb. I have just finished my engine see 32x40 gas engine in the work in progress section it has a propane carb that I designed it has adjustable idle and main jets and works very well, I also made the demand valve from Howell plans If you think I can help just ask,
.
Brian.

 

[fourstroke]

Hello again

I havent had much workshop time lately due to life getting in the way but I have had a little progress
In the first post I showed the brass flywheels I cast at home, after thinking about it I decided brass would look out of place and had some flywheels cast in iron using my patterns at a local foundry. This instalment shows two of them being machined, not a lot of interesting detail in the pictures I'm afraid. The keway slot was cut using a home made keway cutter
Hope you enjoy

Dougie

 

[fourstroke]

I havent had much workshop time lately but I had been thinking about the design of the camshaft bush on the gear side. This was made big enough to let the cams slide into the crankase with the gear fixed to the shaft, three countersunk screws held it in place, so far so good. What I hadnt considered was the size of the gear itself, the first two pictures show the problem, the gear when fitted would cover the screw heads preventing removal or re assembly, also one of the intermediate gears would have to be removed to get the bush out.
So when I got into the shop today I had to alter the bush and the securing method.
I cut an arc out of the flange to pass the idler gear, fitted a pin in place of one of the screws to stop it rotating and drilled and tapped a 6BA hole to take a screw that fixed the flange under its head, the next two pics show the modifications
I have decided to fit the magnet for the hall system ignition I plan to use inside a dummy magneto. It will be chain driven from the camshaft, the last set of pictures show the basic frame with the brass bushes yet to be cut to size and the unit with the sprocket fitted, its not finished and I will post pictures of the interior and
advance / retard lever in my next post
Anyway I hope you enjoy
Dougie

 

[Chiptosser]

Just picked up on this build.
Great job, on making the patterns!
That is a nice size engine, good job on all of it .
I really like the mini Mag!
Excellent!

 

[fourstroke]

I made some progress on the engine tonight that I wanted to share. I also have a request for help from somone reading this in the US
The first pictures are of the completed dummy magneto, the dimple on the rotor is where the magnet for the hall sensor to go later, its 2mm dia by 1mm thick. Attached to the brass advance/retard lever is an angle cut from tufnol sheet, this has the hall sensor, a OH090U glued to it, more on this later.
The view from the other side shows the leads ready to be soldered to their respective wires. the cover has been cut to clear the lever and limit its travel

The bracket for the mag was cut and bent to suit and a web was silver soldered to the underside to stifen it. This is held to the cam gear case with three screws

I also cut the spacers needed to set the cam position on the shaft from brass tube, the main bearings have been cut to allow oil to collect and lubricate the shaft

The last few pictures show the magneto in position with the sprockets and chain drive. The wires for the sensor and the lead for the spark plug will be fed through a hole in the base and routed to the ignition box, the spark lead will come through a hole in the rear of the mag.

Now more on the hall sensor, the OH090U and my request for help
These sensors are almost indestructable compared with some I have tried, I can get them in Scotland but only if they are shipped from the US from digikey or farnell and the shipping is the killer. Both companies want between £12-15 shipping, I guess thats about $18-20.
Is there anybody willing to post some of these to me if I pay all the costs? They will fit in a normal envolope and having had a small jiffy bag sent from California for just $5 I think I can save a fair bit of money. They cost a couple of dollars each and I can paypal any money required beforehand. Anybody who thinks they can help please PM me

Enjoy and as always comments and suggestions will be welcome
Regards
Dougie

 

[fourstroke]

I was finally ready to set the cams onto the camshaft in their correct positions and angles
I set up the camshaft in the rotary table, one of the spacers had previously been glued to the shaft with loctite so that I knew where the first cam had to sit
I made a simple jig from a stip of brass with a cutout that matched the cam profile filed into it. This was set up on packing to bring the tip of the cam to centre height. The rotary table was zeroed and the cam was given a good coating of glue, spread evenly and then set using the jig. A couple of minuites set the loctite.
The spacer and the second cam were slid onto the shaft, the rotary table was rotated 110 deg and the process repeated. The final spacer was loctited into place and now it just needs to cure

Enjoy

Dougie

 

[bmac2]

Hi Dougie
I feel your pain when it comes to sourcing electronic parts. There used to be a strong electronics industry in Alberta but it’s gone now and most anything I want I have to bring in from the states. Back when I was building my Webster-ish engine I had gone into the only electronics supplier left in the city and the girl at the counter looked at me like I’d grown a third eye when I asked about hall effect sensors.oh:
Enough of my ranting . . .

That has to be about the slickest way to set up a cam I think I have ever seen. Being a newb to IC engines it takes some of the fear out of it for me. Thanks for posting it.

 

[fourstroke]

After searching the internet for suitable carb designs and getting some advice and plans from members on here I found a couple of drawings in old books that look took my fancy. I settled on the design shown here and made a few changes to suit my engine and wanted to show you what I did and ask for comments

It is described as a "floatless" carb which is what I wanted, it may also be suitable for use with propane which is a bonus. The first picture is the drawing I found in the book, the next is the basic parts of my version, the two brass tubes silver soldered at an angle are the fuel inlet and the needle valve housing, the two other pieces are the basic main body, these are 5/8" dia with an 11mm shoulder. The next pic shows the three cutouts for the bolting bosses being cut, followed by the bodies with the mounting flanges and bosses silver soldered into place, the needle valves are shown to the side.
The bodies were bored to size and the taper for the valve seat cut in the three jaw chuck, the fuel/needle valve assembly was soldered to the main body to complete the assembly. The next picture shows the hole for the fuel cut through to meet the valve seat. Now, this is where it gets a bit experimental, I have made two carbs, one for each engine. One carb has a 1mm fuel hole cut into the seat, the other has a 1.4mm hole. I did this because I wasnt sure how much fuel would be atomised and can try both carbs on the one engine to see if there is a difference, any comments or advice will be appreciated
A veiw ito the main body with the valve in place is next

The valve is shown next followed by the valve guide, these are held in place by the pressure of the spring on the valve shaft pulling it onto its seat, the knurled nut is to adjust the spring tension and the steel handle allows the air hole to be closed or opened. The next pic shows the carb cap, the screw is to adjust the amount of lift the valve has. The cap is held to the body by three 10BA screws.

The final pictures show the complete assembly from different angles

I hope you enjoy these pics and as always, comments, suggestions or advice will be greatly appreciated
Regards

Dougie