I know this thread is from the Late Triassic period, but I know that power valve problems will go on forever...
So I saw the reference to cutting the spring to weaken the resistance to vacuum pressure and I was going to try it to solve my problem with flooding under load.
Then I thought of two things: Cutting a spring in front suspension actually makes it stiffer. A spring is like a v-shaped lever (in simple physics terms) so when you cut it you have a shorter lever to twist the spring material. Not sure if this would be the case with a progressive spring but was enough to make me think a bit harder.
Also, once you cut it, you can't uncut it.
So I had a flash of inspiration and made an adjustable version which works! Took me 5 minutes...
I drilled a small hole in the spring-guide tube and put a shortened screw in it. See pic.
I didn't have a nice little machine screw but turned out that this one works fine, just a bit scruffy looking.
So what I can do now is rotate the spring so it compresses at the top, leaving the bottom half to do the work! It's very easy to adjust and you can easily feel the tension on the plunger.
Weber should copy this and pay me a commission I reckon!
Two things to watch is that the screw doesn't foul the float and that the screw doesn't press the piston. But the tube is quite thick and I had no problem getting the ugly screw to bite.
Hope this helps someone else with the same issue...
Attached Image(s)
