Gallery, Projects and General > Project Logs
Webster IC Engine build log.
raynerd:
Thanks Ken. My parts a looking better but I`m a long way off your standard :dremel:
I guess we`ll hopefully find out how well it runs in the next few nights!
Chris
dbvandy:
--- Quote from: craynerd on May 03, 2011, 07:08:51 AM ---Nick, you made your post while I was posting an update. Yes, it is a good point! I`m not too sure how or if you would put a viewing window in a vertical tank, also the air inlet stream needs to blow down on the fuel to create the vapour. Jans first design was the bubble carb, where the fuel actually bubbled through the fuel. This seems like a really great way to vapourise the fuel so I`m not too sure why he changed it. With this new version, the tank is only filled about half full and the pipe intentially does not go below the fuel level. It is an interesting concept the vapour carb, I just hope it works for me :D
--- End quote ---
Your valve and tank look excellent. One thing that my grandfather always told me... got gas, got spark, got to go...
Not that I am an expert in the intricacies of the vapor carb, but I do have 30-40 hours perfecting my two incarnations. The first one was based upon pictures of Jan's tank that I used on the webster with the threaded sleeve that covered the hole in the intake tube. It works very well and little adjustment is needed to keep it running. You will find that you do not want to fill the tank over half because it will slosh around a bit when running and raw fuel will get sucked into the intake and flood the engine. Jan and I have been emailing about a better design that has the intake port coming out of the top of the tank instead of the side and that will prevent 99% of this problem and it looks like in some of his new videos that is exactly what he is now doing.
For the Otto I went with a completely new design that works extraordinarily well. The entire tank is see through (glass) and the metering valve is a simple bolt that covers the air bypass hole to adjust the mixture. This could EASILY be tilted upright to make a vertical tank. Once the super volatile fumes are burned off (30 seconds of running), the engine only need minor adjustments to keep it at any RPM I would like it to be, from 700 RPM all the way to 5400 RPM. ALSO... there are two ways to control the idle revs; one is to make it too lean (less gas) by adding more air and the second is to close the air valve off and make it too rich (more gas). The first method is less sensitive and the idle stays pretty constant throughout the entire tank (30 minutes of running). One drawback is when it leans out, it runs hotter quicker, but it does not stink as much as when it is too rich and puffing out unburnt fuel. Only when you get to the very bottom of the tank when only the crud remains is it harder to keep it at a particular RPM.
http://madmodder.net/index.php?topic=4425.msg50253#msg50253
You will also find that the air does not have to hit the fuel to make a vapor. The vibrations of the motor disturb the fuel enough to make good vapor. I had a tube that went to the bottom of the tank on the webster and it just made it slosh around more, not helping the vapor mix in the slightest.
Looks great, and as long as the valves seal well and you have sealed the valve block to the engine completely, it will run without a doubt!
Doug
madjackghengis:
Hi Chris, great looking set of parts you've got, you must be very close to running, and I'm getting a lot out of the questions and answers on the vapor carb which help, as I expect to be using one soon. It makes perfect sense that you're getting enough vapor from vibration and sloshing, particularly with a small, single cylinder engine, and I would think if you needed more vapor action, the intake through fuel would be good, and you could use a "dome", as in a steam boiler, to prevent liquid from sloshing up into the intake if you ended up powering a traction machine with this engine or something of the like. One of the things I like most about the vapor carbs is the fact you get to see what's happening inside, and can alter and adjust for what is visible, and not just guessed at. I've put the equivalent of a "dome" in a gas tank for a motorcycle, to allow a sealed fuel cap, and still have a good working venting system which won't pour fuel when sloshed, and with a tube sticking up from the tank, the bottom 3/4 in of a CO2 cartridge over it, and a couple of holes drilled around the tube, which is soldered to the tank on the top, where it enters the "dome", and soldered at the bottom where it goes through the tank and vents down under the bike with a bit of hose, it works well as a vent, and keeps gas from venting on the paint, ruining the paint, as if that were an important issue. I'm glad you chose to put a couple of blocks for a base, I didn't want to see you machine flats on the bottom of the brass, it looks real fine the way you did it. :ddb: :beer: Cheers, Jack
raynerd:
Hi Madjack - Yes, the base is just a temporary fix, I`m still not thrilled, I think perhaps they need profiling a little more just to give them a nice look. That can come later! Vapour carb sure does look good, I hope it runs as well!
Doug, interesting post you made! Have you got any advice regarding the timing? I`ve been reading over the build notes and I`m trying to make sense of it!
Chris
NickG:
Chris,
car engines usually fire at around 10deg before top dead centre. You might not need it as advanced as that so I'd prob just experiement starting from a couple of degrees ... that's degrees on the main crank, so the spark should occur a few degrees before top dead centre (compression stroke, both valves closed) what do the notes say?
That's assuming you meant ignition timing!
Nick
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version