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Webster IC Engine build log.
NickG:
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:
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:
Looking good Chris
Stew
saw:
Looking very nice, good work. :thumbup: :clap: :clap:
dbvandy:
--- 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?
--- End quote ---
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
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