Webster IC Engine - nearly there...!

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Aug 13, 2009
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Well it is never as interesting when a post is made in bulk like this but I wanted to post my Webster Engine progress on HMEM. I think some of you may have been following this on madmodder.
I decided on the Webster as a simple build (I use the word simple loosely) I started to get materials collected. I snagged a lot of aluminium plate from the scrap heap several months ago and finally I`ve been lucky in the fact that I`ve got pretty much all the sizes I`ll need.

Unfortunately I did not have the cast iron or leaded steel for the cylinder so I purchased that

I`m also changing from the plans and will be using 8mm silver steel for the crank rather than the imperial .313" that is stated. I`m also going to run the crank in bearings rather than brass bushes as stated and these arrived last week:

I also ordered a small NPK spark plug that cost £3 on ebay but I`ll need a M10 x 1.0 tap which is annoying, my M10 taps are all M10 x1.25mm.
Then it comes to the gears!! I`m going to try and cut the gears. Thankfully in my efforts in my continuing clock build I`ve attempted several gears so I`m quite comfortable about giving these a crack. Involute spur gear cutters are MUCH cheaper, at about £20 a cutter than Cycloidal clock wheel (gear) cutters which sell for about £60-80 a cutter! Despite this fact, I`m going to try and make my own cutter again using the methods and calculations provided by John Stevenson on the web. I`ve done all the calculations, they are here:
Well after all that thinking :med: :coffee: :scratch:... time for some chips :dremel:.
It always takes me bloody ages to just cut the pieces, infact it took me a few nights just to rough out a few pieces from the big sheets of aluminium. Here are the two side supports, the one blued up is to size, the back longer support is just roughed out.


I`m in a bit of a pickle with regards to the base. I`ve nothing really suitable and can`t afford a piece of ally big enough just for the base of this. I think this piece will do, but it is a little bit thin, then again my plan is to raise the base on pillars so the electrics can go under it.


I`ve also been preparing for cutting the cylinder bore which I`m going to do between centres. Lots of good advice was given here:


and in preparation I made this bore setting device:

And with so much success, I had to fall over some where!

looking good so far:

yea... then I thought I could just not show it hence the angle of the photo...but look at the fins :(


but hey ho! I`m going to go and bore it and hopefully it`ll still run, just the gap between the fins is wrong. Two stupid errors, I misread the plans and then to compound the issue, the work managed to move from the 3 jaw during grooving!!

Here is the cylinder with the roughed out cylinder support piece:

...and that is pretty much where I am up to right now. Next job is to mount the cylinder again for boring between centres.
I managed to make my boring bar from a 0.625" silver steel bar and small piece of HSS. I also found the wood I needed to mount the cylinder (I lied, I didn`t find it, I purchased 8 foot for only
12" - meh, it`ll come in hand!!)


Here is the wooden block:


I actually used this cutter for the wood, the other was too fine a point and was ripping the wood rather than cutting it. Cutting the bore was also good practice!

So here is the mock up - as you can see my bar was 0.625" so only needed a small projection of the cutter. It was nice and sharp and the cast just powdered off.

Bore all nicely cut and final cylinder ready!


Well this method took a lot of effort and many hours of extra work in making the necessary tools but I`m really pleased with how it turned out and certainly another method under my belt for future. Good finish as well! Bore is bang on 0.875 perhaps touching 0.876" - certainly good enough for me and I hope good enough to run!
I bored the blind 1" cylinder neck support in the 4 jaw on the lathe. I`m becoming increasingly fond of m 4-jaw, it use to scare me but now it is becoming a good friend! Sadly the material I was hoping to use for the cylinder support was not wide enough and the only thing I had wide enough was not long enough. As I didn`t want to purchase more materials, I have used what I have and added a brass rising block to increase the length.

Then for the long support whittled from this piece of ally:

All the parts resting on each other with a little block under the cylinder to stop everything falling over!


Parts so far:

For cutting the gear I made this gear cutter form tool:

Yep, cheers for the encouragement MadJack I need it after the last two days attempts. I`m pulling my hair out here!!
I heat treated the button cutters and all looked well. I hacked off a large piece of silver steel for the cutter itself and mounted on the arbour stew made for me last time I did some gear cutting. Here is the intended blank of silver steel to made into the cutter:


I then parted off the 0.125" wide cutter I needed after centre drilling for fitting onto the arbour.

I re-ground my cutters and made sure they were sharp. It cut very well, although one side cut better than the other which was a bit annoying, but it did cut. I ended up with this:

So I cut the disk in half and bored it square to the face, hardened and tempered. Needs a final grind now and sharepen but that is as far as I got:

Now this picture concerns me a little - I think it is the angle that I`ve presented it to the camera but the cutter looks a little bent. It doesn`t look like this in real life so I`m hoping it is an optical illusion. I`m posting the picture anyway, it shows a rough profile of the cutter:

I first went around with a slitting saw, obviously of smaller width the cutter tip and to just a few thou short of the full cut.


This removed a good bulk of the metal and as soon as I swapped over to the gear cutter, I could tell cutting the first tooth that cutting was much smoother! The cutter did pick up a bit of a burr (I think perhaps I need to make sure my next cutter is a bit sharper)


I also used a much bigger washer to protect the little spigot but it also supported my teeth more even though it meant cutting into it. I don`t think I needed it actually but still, it seemed to work.


...and then cleaned up and put on some 8mm silver steel for a proud picture :ddb: I`m chuffed :D So just like the plans call for, a 48 tooth 32dp gear. I just need to make a 24 tooth gear that will mesh with it...I guess that is the real proof of the pudding!

I decided to solder the crank together. I`ve done very little soldering and it didn`t go too well. I didn`t get the part hot enough and so the solder clumped on the metal rather than flowing in the joints. I got there in the end but there was more tidying up of the part than should really have been needed.

Here are the parts assembled along with the base and con rod. At all joints which require bushings on the plans, I`ve used bearings. My intention is to use a bushing on the piston wristpin.

And finally the parts "posed" together! The gear under the cylinder is proping it up as it isn`t bolted down just yet.

I ordered this electronic ignition kit:

I also had to made an adapter for the small 24 tooth spur gear so that it could be also held to the crank. The plans call for the spur gear to be attached to the flywheen but I figured I`d have no problems just using grub screws to fasten each to the crank independently.



Here is the con rod and piston.



So it is looking quite good now and turns nicely with a push on the flywheel yet has a great piston seal.

I thought I`d try something different to make my cam. My idea was that if I cut the OD to that of the "lug" of the cam and then placed the blank on my CNC rotary table. The problem with this method is that it would create a slight radius upto the lug which should ideally be flat. If I used a large enough cutter, with the cam being so small then the radius would be minimum and in my opinion, shouldn`t effect anything...I may stand corrected!!

I did some calculations because I needed to work out the angle I needed to turn the rotab to end up with the correct width of the lug on the cam. Not very interesting but here are the calcs...


I then set about machining:

Nice and slow, but you can see the lug forming. I was just going back and forward using the rotab.

Then removed, centered in the 4 jaw and reamed off plan so that it would suit the mount on my 48 tooth gear I made.


and here it is with the gear mounted the wrong way around so I could see the cam acting on the exhaust lever.


And here is the lever part way through machining. I enjoyed doing this piece, it was quite straight forward yet an interesting shape:

And all together... once again the gear is mounted the wrong way around so we can see the cam!


So the next job now which I am absolutely dreading is the valve block - I really need to get my head around this, how it is machined and what the parts are even doing!

Could anyone who has made the webster explain, or ideally a photo, to show how you have made your spring to keep the lever lifted?

I also got a nice supprise in the post today...

I moved onto the valve block.I really struggled to come to a decision on how to machine this. As far as I could see, the important factors were that the 3 blocks had to have a perfectly flat surfaces to mate well (I expect gaskets will be used still) and that one of the long sides will be perfectly flat so that it will seal well with the cylinder head. I needed to convert the bolt holes to metric because I didn`t want to go searching for the imperial bolts. I changed them all to M3, but it was hard work as they were quite close to holes colliding with one another going through in all directions.

I wanted to use brass so I took one of my stock 1.5" square bars and cut off 3 slithers. I then faced up the surfaces to thickness. I moved from the plans as another builder, Doug, advised, making the top and bottom block a little thicker to allow a better connection with the exhaust and intake.


So now do I work on each individually and hope they all square up at the end? No chance, I know my limitations and the only way I would get everything to locate would be to make it as one block. So I marked out the top block but allowed 1mm the close sides to machine back as well so in reality I didn`t have a datum face yet.

I then clamped, drilled through the top two blocks and tapped the bottom block, holding them all together.

I then spent a long time aligning the bolts with the new face that was to be cut, i.e getting the bolts parallel with the bed. I then squared up the rest of the block to size:

I then centre drilled (and will located off this hole when I took it apart to increase the hole dia of the two out blocks. I then horizontally drilled the two holes to bolt the block the head. This was near to colliding with the centre hole and the 4 holes holding the block together. I had concerns the drill would wander and intercept another hole ruining the block but I peck drilled slowly and all was fine! I then countersunk the holes for countersunk allen screws.

From the other side, the 0.188" hole is drilled into the centre bore of the valve block which connects to the head.

I then took to block apart so that I could drill and counter drill the outside blocks to insert the valve guides.

And this is where I am currently at... an exploded photo showing the top valve guide fully inserted and the bottom valve guide about to be pushed into position.

One of the valve guides is a fantastic pressure fit, the other is just a "good" fit so I hope that the loctite I use will provide a good enough seal. I expect it will. So the next job is to loctite them in place once I`m happy everything is ok, let that set and then drill into the side of the blocks, through the guides for the exhaust and inlet holes.
Here are the valve and valve blanks made from two piece and silver soldered.

Well really feel for the first time like I`m getting somewhere now!
I have finished the valve except the springs - need to sort those out as currently they are just 2 random springs I found just to hold it all together.

And I managed to get an M10 tap with a fine pitch for the spark plug and so far, assembled it looks like this:

I`ve got a little further with the engine, in fact I have made the magnet holder which connects to the crank. I also ordered some 3mm magnets yesterday which arrived today so I put it all together for a quick test. The video isn`t great, but I`m pleased that it is sparking!! The sensor is just strapped to that steel bar for a temporary fix, it is going to be held through a brass tube or similar.



I also started work on Jan Ridders vapour carb. I couldn`t find any brass tube at a decent price and when I went to my local scrappy yesterday, I picked up the solid bar end for less than I would have paid for a length of tube.

Since I don`t have any silver solder (will pick some up at the Harrogate Show), I wanted to keep any soldering to a minimum. Rather than bore a tube and then cap it, I figured I may as well leave one end solid. Here it is part way through machining.

Jan suggests 45mm inside diameter, the only glass disc I could get my hands on was 50mm!

And then finally machined down some more and also the recess made for the glass disk - the glass disk which is the fuel tank viewing window is actually in position in the photo, so looks good and a nice fit! I`m a bit worried about sticking it in place and getting a good seal!

I have left it in the state of the last picture. I need to sleep on the next step and would appreciate any advice. I would quite like to machine a larger diameter at the ends, a bit like if I had capped it and had an overhang on the cap. The only way I can see I can do this is if I use some sort of stub mandrel and taper it to go into the bore, then machine the outer diameter all from that. It just seems a large bore to attempt this with.

The other thought is with holding it, i.e a base or stand for the tank. Does anyone know if there is any sort of height restriction, I guess the fuel level should be lower than the cylinder bottom or does it really not matter? I could make two little stands to sit it on like Jan or I was thinking about soldering a bar into the bottom of the tank, tapping the bottom of the bar and then screwing it down from under the base.

The third option was with so much material, to mill a flat on the bottom of the tank and just sit it on the base!! Seems a shame removing so much brass (£££££ :doh:) but then I think it looks a bit large when sat next to my model, especially with my small ally base.

So that is where I`m upto… I know it isn`t quite as interesting when posted in a big lump but I`ll keep it up to date from here on in…

Any suggestions or thoughts regarding the fuel tank as mentioned above?

Hi Chris
keep at it buddy
The Webster was my first project and not nearly as nice as yours is turning out!
and I still have not learnt how to make my own gears
I think you are doing a splendid job so far Chris. Thm: Seeing how others approach the different steps has always been of interest to me. :eek: Also, seeing and hearing the builders expressions of artful, creative flourishes, 8) gets my blood pumping as well. Do take care in the mounting of your hall effects pickup, it seems that many have encountered problems for various reasons recently. It won't be long now until the moment of truth arrives and with a bit of luck we will be seeing a video spot of your latest creation as it springs to life.

Thanks for the replies chaps. Yes, I am fairly sure the moment of truth with actually end up being a month of rebuilding parts followed by another month of fine tuning!!

I`m well under way with Jan Ridders Universal Carb so I shall be posted an update shortly.

looking fantastic, Chris. Please post some photos and info about your Jan Ridders carb build if you have the time. Thanks.
Thanks for the interest Richard, here is a follow up from my last post...

Following on from the last pictures ...

I turned the OD of fuel tank / vapour carb down to make a nice looking brass cup :D

The top air intake is two piece. An M10 tapped insert soldered into place to allow filling of the tank and then a screwed insert for the air intake reducing the air intake to an 3mm hole tube. The shoulder of the insert is contoured on the shoulder to allow it to sit nicely on the tank. I couldn`t for the life of me think how to do this and so a friend and fellow madmodder suggested a two piece design, where a washer is used as part of the shoulder and the washer filed and sanded to shape. This worked really well but I would be interested to know how this could be made from 1 piece as per the plans

The fuel/vapour outlet tube was then made...not the best photo but all the parts here are ready for soldering..

My sophisticated soldering setup...the cooker top.

And then all polished up... I`m really pleased with it! I just need to make the main air intake insert and the nut which covers the additional air intake on the threaded outlet, glue on the glass viewing window and put it on a stand and then I`m done. Getting there...!


I believe I`ll need a one way valve as a must as well, so they will be the next things to make.

The carb looks great so far, Chris - thanks for the pictures and detail. I hope it works as well as advertised!
Great looking build you have going here. The vapor fuel tank turned out really nice. Anxious to see the finished product!

Thank you chaps.

Chuck - it was actually when googling "carbs" a few months ago that I came first across your posts regarding simplified vapour carbs - so you brought me down this line in the first place! So thanks :D

Can I ask, what would be a good gasket material for between the valve block and cylinder head?

I believe I don`t need a one way ball valve on the fuel inlet one the valve block as the valve would shut if there was a blow back with this design. However, when googling Webster Engines, I found a post on HMEM where you fellows were trying to help someone get their Webster to run and you advised a ball valve, so I made one anyway.
Here are the pics...and far too many of them, I got carried away! It all still needs a good polish.

Starting off with finishing the fuel tank. The images previous didn`t include the intake tube insert or the air intake adjuster nut..





Is that enough...or perhaps one more? :lol:


Then I went on to make the little one way ball valve as per Jan Ridders plans:




I`m getting close...I can almost smell the fumes. I`m joking as I know for a fact this won`t run :doh:

Infact, other than an exhaust pipe which I presume I don`t need to test it, I think that is everything other than a mounting block for the sensor!!

Dont jinx it buddy
if u have compression,fuel and a spark at the right time its gotta go bang :big:
Yea, I need some confidence. Hopefully I`ll find out this evening!

I am right in thinking that I don`t need a exhaust pipe?
Hi craynerd.
"I am right in thinking that I don`t need a exhaust pipe?"
YES Sir.
Buuuut, if you don't make the exhaust now, and you get the Webster rrrrrrrrrunnnnnnnnnning,(I'm sure it will) ;)
it will take some time before you make one ;D. How do I know? Been there... ;D ;D
It will be so much fun when you have the first purrr. that you will forget making one until the whole geartrain is messed up with black gunk :big:.(for the same reason make the exhaust pointing up)
Nice wrigth-up,nice engine.

Best Regards

Well no luck with an hour or so on it last night. It coughed a few times but that is it.

I put an O-ring on the piston and I have to admit, it made a difference. I cut the groove a little deeper than I calculated as it was just binding a bit too much.

When I put the engine together, I put the piston in the cylinder and spark plug on the end. I couldn`t compress the cylinder with my finger over the hole in the cylinder head. Likewise it hurt my finger sucking on it when I pulled the piston out. I`ve definately got a good cylinder/piston seal.

I put the valve all together again and actually gave it a bit more of a grind in its seat. Sucking by mouth through the valve block with the springs in position doesn`t let any air through so I`m sure the valves have an excellent seal. (Before I gave it the extra grind I think there was a little air getting through one of the valves). The valve block is perfectly flat and I`ve used a small amount of hylotyte red between the head and valve block - only a small amount but just something to seal it for sure.

I`ve also remade the flywheel. The steel one, although with a lovely hub was not heavy enough. This cast one seems much better. I used Johns suggestion of tapping through small holes between the cast iron outer rim and the brass centre hub, screwing into these and then facing the heads flat. This was a super idea and has locked the hub in position for sure.

I can hear the spark plug, like I said, I had an issue with some seemingly random sparking last night which I`ll investigate later but hopefully it has stopped I think I need a connection between the engine base and the electronics box to ensure that the spark isn`t tempted to jump across to the outer sleeve of the spark plug cap rather than sparking at the cap.

It all seems good to me and with Doug telling me that I won`t necessarly see the top spring moving until it gets going then I`m more confident.

My only issue is that when packing away last night, I got a small drop of fuel in the pipe. Turning the engine over by hand, you can see the fuel moving up towards the valve block (cylinder) by the suction of the piston moving out on the intake stroke but it also moves back a little during the compression stroke and even a little on the exhaust stroke. I don`t know if I should worry about this, I thought the valve should be shut during the compression or exaust stroke and so the fuel shouldn`t go back down the line...then again only a tiny tiny change in pressure would cause this to happen.

I can only presume it is my timing and as I said earlier, I need to start it with a drill for testing rather than a pull string. I`ve just got a small rubber ring off a lego tractor wheel and so I`ll make some sort of rim for this tonight and then I can use it on my drill to start the engine

Any further advice or info would be welcomed. I`m concerned about this random sparking I can hear, I hope it stops tonight...I can`t imagine what is causing it.
Hello Craynerd, I have been casually following along as I enjoy the charm and overall simplicity of the Webster engine. One thing that jumped out to me about your starting issue problem was what you said regarding visual confirmation of fuel being forced back into the line while the engine is on the exhaust stroke as well as on the compression stroke. That would indicate to me that your valves are not sealing 100%. Have you attempted to lap the valves with some fine clover compound? Get your valves to seal 100% and I believe you will get your engine to run reliably. Best of luck and we all are looking forward to seeing your success.


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