Author Topic: Webster IC Engine build log. (Read 244065 times)

NickG · « **Reply #150 on:** April 04, 2011, 12:48:23 PM »

I just hand filed it for the flame gulper - somewhat of a different shape on an ic but sure it could be done. The shape may be a bit more critical on yours.

raynerd · « **Reply #151 on:** April 07, 2011, 04:36:04 PM »

Hello, I`ve got a bit more done on the Webster. 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...

http://raynerd.co.uk/wp-content/upLoads/camdata.jpg

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...

but more on this soon....

Cheers
Chris

sbwhart · « **Reply #152 on:** April 07, 2011, 04:38:58 PM »

Looking good Chris

Stew

saw · « **Reply #153 on:** April 07, 2011, 05:00:52 PM »

Looking very nice, good work.

dbvandy · « **Reply #154 on:** April 07, 2011, 08:00:38 PM »

Quote from: craynerd on April 07, 2011, 04:36:04 PM

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 did not use a spring on the rocker rod to keep it up. most people that I have seen do not even use one, I did not need it. The only real thing it will do is help quiet the rocker down when it slams up against the cam.

The valve block is in 3 parts. The plans call for 1/4 inch stock, I did 5/16 so that I could have a little more meat between the valve guide and the edge of the block. also, I did not want to use 4-40 screws to bolt it to the head, I used 6-32 so I could tighten it down a little tighter.

http://madmodder.net/index.php?topic=4413.msg48377#msg48377

I also wanted my exhaust to point up, so I made the exhaust a bit longer and drilled a hole in the top for the pipe.

THE most important thing with the valves is doing the face and stem in one setup so that they are concentric... same with the guide. Do the guide first and drill out the hole for the stem. then you can measure it with a numbered drill and match the stem to it perfectly. Mine are .007 different (don't know how the heck that happened, same drill, same setup...), but the valve stem was turned to match, so there is .0025 clearance on each.

One other thing is to plan on making some paper gaskets for the two faces. Do not depend on a nice surface to seal, the 4-40 screws can't put enough pressure on the two port plates to seal it good. I also put an o-ring and a piece of brass tubing between the head and the manifold. It gets VERY hot because of the exhaust gasses, so do not use any liquid sealer of any kind, it will just melt and gum up your piston (ask me how I know...)

If you can get it there, get some high temp loctite, as it is good up to almost 400 degrees to seal the valve guide into the ports.

Doug

raynerd · « **Reply #155 on:** April 08, 2011, 06:23:53 AM »

Thanks for your reply but I hate to say - I don`t know the jargon your using so can`t identify the areas you are mentioning!

I`d really appreciate it if you or someone could explain what parts you mean here:

Quote

THE most important thing with the valves is doing the face and stem in one setup so that they are concentric... same with the guide. Do the guide first and drill out the hole for the stem. then you can measure it with a numbered drill and match the stem to it perfectly. Mine are .007 different (don't know how the heck that happened, same drill, same setup...), but the valve stem was turned to match, so there is .0025 clearance on each.

I`m not clear where the face and stem are, and what you are explaining should be concentric? Sorry !! Also, where is the head and manifold? Is this where the valve block aligns with the cylinder support inlet?

I`ve also been trying to figure out how the valve opperates and I can`t get it to work in my head. Take the bottom exhaust block of valve block. The valve head sits in the valve guide and is kept square. The spring pulls on the valve guide to pull the valve head to the bottom of the guide. This allows exahust gases to pass from the cylinder out through the centre block and out down the exhaust. When the cam comes around and lifts the valve, this is going to lift the valve head past the exhaust hole and stop the exhaust. This is the wrong way around then it should be working!!! I`ve drawn some diagrams and in my opinion the exhaust should be open for 1/4 of the cycle, which makes sense, 1/4 of the 4 strokes (1 stroke). The way I see the valve block opperating is the opposite. It will be open for 3 strokes and closed for one.
I can`t see at all how the top inlet valve is working since there is nothing acting on that sprung valve - or does it open by its own cylinder pressure?

Any help, advice or explanation would be hugely appreciated!

Chris

dbvandy · « **Reply #156 on:** April 08, 2011, 09:51:11 AM »

Hope this helps...

This is the most critical part of the build and must be the most precise. If your valves leak even a slight amount, the engine will not run right. if you take your time and get the dimensions correct and on the same axis, it will seal perfectly. You can do this....

Doug

NickG · « **Reply #157 on:** April 08, 2011, 03:46:36 PM »

Chris,

you're right about the valve being open for approx 1/4 of a cycle or 1 stroke. The angle on the cam from the point where it starts to open the valve, to the point where it is fully shut again will be about 90 degrees. Don't forget that it's driven at 1:2 ratio though so for that 90 degrees the piston will have done a full stroke.

Nick

raynerd · « **Reply #158 on:** April 08, 2011, 05:58:23 PM »

Doug

Thank you for the time taken in your reply! It has cleared everything up

I`ll tell you where I was making my error (like a fool)...

You see in the right hand diagram, .188" from the bottom, it shows an angle cut at the end of the large hole. I stupidly thought this was the valve seat angle! So I thought the valve seated lower then the inlet/exhaust hole and couldn`t understand how it was closing. Clearly now looking at it the valve head wouldn`t fit but it certainly got me. Anyway...with all that cleared up, I`ll be making a start tomorrow!

Nick - it is good to see I have got something right!!

Chris

NickG · « **Reply #159 on:** April 09, 2011, 02:43:42 AM »

Chris, I've spent years studying the theory of this but probably never dared to take the plunge - at least you've just got out and started making it - which puts you way ahead of me now

raynerd · « **Reply #160 on:** April 09, 2011, 05:12:23 PM »

Nick, lol, I`ll be ahead of you if it works!

This valve will be a miracle if it works!!

raynerd · « **Reply #161 on:** April 09, 2011, 05:34:04 PM »

I thought I`d start with the valve guides. I did consider the blocks first but considering the valve guides would have to be machined with the large end towards the tailstock, I wouldn`t be able to check for a good fit in the block anyway, so thought I`d start with these!!

This was a tricky little task, very small with quite a bit of detail! I did what I thought was the best order of machining and ended up with them complete and just requiring parting off to size on the end of the rod!!

j45on · « **Reply #162 on:** April 09, 2011, 05:41:40 PM »

Wow nice job on those Chris

they are tiny

saw · « **Reply #163 on:** April 09, 2011, 05:44:29 PM »

Amazing, you rock

dbvandy · « **Reply #164 on:** April 10, 2011, 01:28:28 AM »

They look GREAT! I had some bronze bolts that I used for mine.

I remember when I was doing the guides and valves for the Otto that I was amazed at how large they were after doing the ones for the Webster.

If you use a numbered drill to check the exact size of the guide hole and make the stem of the valve to match, it should work perfectly!

Do you plan on winding your own springs?

Doug

madjackghengis · « **Reply #165 on:** April 10, 2011, 11:22:01 AM »

Hi Chris, I watch your build with enthusiasm and a bit of amusement, as what you are doing is what I've done most of my life on a larger scale, and yet the exact same issues are important and confront the engine builder. From that perspective, remember that paper gaskets not only seal things up, they also act as heat dams, reducing transferred heat to things like carbonators, which sometimes makes the difference between barely running, and a great running engine. I have used a piece of shirt cardboard, spray painted on both sides with aluminum paint, several coats letting each dry in between, as head gaskets for motorcycles and car engines, when I couldn't afford or couldn't get real gaskets. Those guides and seats turned out great, and should be just the thing to make it run well, I'm looking forward to the video of it running.

Cheers, Jack

dbvandy · « **Reply #166 on:** April 12, 2011, 09:46:44 PM »

I hate that we lost a few days worth of posts....

raynerd · « **Reply #167 on:** April 13, 2011, 02:27:37 AM »

HAHA - I can`t bloody believe it!!!

If any of you read my reply before it was deleted, I wrote that there must have been another problem with the site because when I clicked to "post" my long reply, it told me the website was down and I lost my post. However, 20 mins later I managed to make another post. Now it has been deleted again, lol,

This post really isn`t meant to be!

I just wanted to say thanks for the words of encouragement from those that posted and had posted but have been deleted due to the server crash.

Madjack - I`m glad your enjoying reading this thread and it is nice to hear that others have the same issues I have!

Doug - I haven`t thought too much about the springs yet. I guess they are quite important in terms of how much pressure they are applying - did you wind your own springs or where did you get them from?

dbvandy · « **Reply #168 on:** April 13, 2011, 10:01:03 PM »

Quote from: craynerd on April 13, 2011, 02:27:37 AM

Doug - I haven`t thought too much about the springs yet. I guess they are quite important in terms of how much pressure they are applying - did you wind your own springs or where did you get them from?

I wound my own for the webster, but not the Otto. it is pretty straight forward and you can get the music wire from about any hobby shop. Any hardware store should have a selection of springs, you just have to make sure the intake is lighter than the exhaust.

You can do it....

Doug

raynerd · « **Reply #169 on:** April 14, 2011, 05:44:55 AM »

Doug - I may very well wind my own then. I have another question if you will; How did you connect the intake and exhaust to the valve block? I know the plans call for drilling 0.188" through the valve blocks into the guide (that is correct isn`t it? - you insert the valve guide into the valve block, loctitie it in and then once set, drill through the block and through the guide so that gases are entering below the valve?) Anyway, my question was how to attach the actual carb or exhaust itself. 0.188" is about 4.7mm, considering I`ve made the block a bit thicker as you advised, would it be worth drilling through the valve block and guide 4.2mm (just under 0.188") and then tap M5 so that any exhaust or intake can be screwed into positions? Or would the seal not be good enough? I just prefer the idea that inlet and exhaust can be changed than permenantly loctited in position. Any thoughts?

Anyway, after playing around with my fire piston, 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. Before all that, I need to cut the valves and use some grinding paste to lap them to the valve guide seats.

saw · « **Reply #170 on:** April 14, 2011, 05:55:32 AM »

It's nice to see how every thing come to place, nice work

dbvandy · « **Reply #171 on:** April 14, 2011, 08:56:55 AM »

Looks EXCELLENT!

I predrilled the the holes into the blocks, then pressed in the guides and then drilled them through. It might not be necessary to do this, but I wanted to make sure it was all lined up before I drilled through the guide as it was easier to make a new block than a new guide and possibly valve)

As for the carb.... I turned an adapter, something like is on page 14. I never could get the RC carbs that I have to work properly, however, so I went with the vapor carb like is in Jan Ridders plans. I really feel this is the way to go as it is fool proof, works really well and you have to build a tank anyway,so why not combine them. If you can get a carb to work, that would be cool, but I found it very frustrating.

You are getting close!!!!!!!!!!!

Doug

raynerd · « **Reply #172 on:** April 14, 2011, 09:48:19 AM »

AHHHHH !! The plans did say to pre-drill! So you actually drill through to where the guide will be inserted, then when you insert the guide, you can see it is located properly so that your only going through the side of the guide and not going to ruin it??

This now makes sense!

Perhaps obvious, but I didn`t understand why predrilling the holes was needed.

raynerd · « **Reply #173 on:** April 14, 2011, 09:53:29 AM »

Sorry Doug - it says that the adapter is loctited to the carb, but what about the other end into the valve block - loctite here as well? I just thought a thread on this end would be better??

dbvandy · « **Reply #174 on:** April 14, 2011, 10:05:35 PM »

Quote from: craynerd on April 14, 2011, 09:53:29 AM

Sorry Doug - it says that the adapter is loctited to the carb, but what about the other end into the valve block - loctite here as well? I just thought a thread on this end would be better??

I have 2 .12 RC motors with carbs that have 10 mm throats, so I loctited the adapter into the valve block and then had a tight slip fit on the carb to adapter part so I could experiment with different setups.

I still HIGHLY suggest you try the vapor carb. You get full throttle response (I could get mine to 5600 RPM and down to 600...) and it is VERY forgiving....

Doug

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Author Topic: Webster IC Engine build log. (Read 244065 times)