Gallery, Projects and General > Project Logs
Webster IC Engine build log.
raynerd:
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.
--- End quote ---
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? :doh:
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:
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:
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:
Doug :beer: :beer: :beer: :bow: Thank you for the time taken in your reply! It has cleared everything up :beer: :beer:
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:
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 :bow:
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version