Sorry, I don't know what you mean by that.The vacuum break is the amount that the choke pull-off pulls the choke off, right after start-up when the vacuum comes up. Pishta explains.
You mean remove the fan belt? How would that affect the crankcase? EDIT: Do you mean so that the fumes blowing out of the breather would be visible instead of being blown away by the fan? No.and yes,lol.The fan could be causing your paper to waffle all about like in the video. We need to eliminate that, so we can tell what's what. The PCV needs to be removed so that it is not affecting what we are seeing; and the hole where it came from needs to be plugged so that any blow by is all forced out the open breather hole. The engine will be fine running without the fan for the few minutes it takes to run the test. Just have it all set up ready to roll when you hit the key, then after the video is recorded, put it all back together.
I do plan to adjust the valves as soon as I get a chance. Then I'll redo the compression test. I think you're suggesting to do it cold just to make sure the temperature is the same for all of the cylinders?Yeah that's right.A seasoned pro can set your valves in a few minutes; a short enough time that the engine's temp will not change over the course of the procedure.Since I am jumping to the conclusion that you might not be a seasoned pro quite yet, my recommendation was just to rule that out.
I believe last time I did it I rechecked 1 and 2 after finishing the others, just to see if anything changed as the block cooled in the interim. But I'm not positive I did that.
I've looked at the choke with the engine idling and air cleaner off, but I don't have a sense for how fully it should close and how quickly it should open at a given ambient temperature. Maybe I can post a video of it.At this time of year, it should snap shut,all the way,snap! Then as soon as it starts, within a couple of seconds, the choke pull-off should draw the choke blade open about 1/8 to 3/16 inch. There is a spec for that, for a new engine, or one that is operating like a new one. For you, if the engine is running rough, within one minute of start-up, manipulate the choke blade and find the perfect opening, to smooth her out. Measure it. Then shut her off and readjust this airgap, which is called the vacuum-break, to your perfect gap, by bending the little loop in the choke pull-off connector link.You will need to apply vacuum to the pull-off to see the results of your activity. You can do this on the running engine(which is best) if you know what you are doing and can do it fast enough. You only have a half a minute or perhaps a minute to get it right, before the choke starts to open the blade and then times up! If you didn't get it, you will have to try again at a later time when the engine is again stone-cold.This is why the spec exists, cuz it can take you several times to get it right.The spec makes it faster, more probable, to get it right the first time.