ORIGINAL: JDW
Flyboy Dave
It's simply not worth discussing this with you - you simply don't read what is written and you obviously have no idea at all about fluid flows and pressure effects with accelerated flows. As I said before - try it - you might like it!
Xjet is on to it - I guess you'll bag him as well!
In the meantime I'll wait until someone else has something intelligent to say on the subject.
Well...you know, JDW....I took you up on your challenge....I figured I might
as well check out your
Magical carburetor geometry and tuning theory.
I must admit, I am a little Old Fashioned and set in my ways. I thought I might
even learn something new. I have real bad news....your theory was just that, a
theory.
It didn't pan out. In fact, everything you stated in your theory proved to be wrong.
At least I gave it a shot. I took my GMS .47 out today and did the idle screw
test. You said the idle screw had everything to do with the high speed mixture.
I said it had nothing to do with the high speed mixture in the WOT position.
Your position was that the leaner you set the low speed, the better the engine
would run....due to a bunch a magical theories that you alone know about. You
claim that leaning out the low end not only cures all the ills of the problematic
GMS .47, but is the
sole source of the fix....and all the other problems
are not in themslves problematic....rather, a waste oF time.
Your magic tuning theory will overcome all these
slight problems !
Well here we go....
1. shows the position of my idle screw, after I had done all the mods, and had
the engine running perfectly....with about .008 distance from the spray bar. It
looks more like .010, but I eyeballed it at .008, so let's leave it a that.
2. shows the actual gap. For those keeping score at home, a matchbook
cover is .013".
I started the engine, and let it warm up for a minute....then I shut it off and
opened the low speed needle 1/2 of a turn. I restarted the engine with an
electric starter each time. I figured that as I enrichened the low end....
moving the low speed needle away from the nozzle would kill any chance
of an idle. I was right.
I opened the low speed needle 4 times....1/2 turn at a time, two full turns out.
Pic 3 shows where the screw ended up. See how much further out it was
when I started, and trust me....it was set perfectly.
Now for the fun part ! See the gap in Picture 4 ? A whopping .060
.
Guess what happened to the high speed ?
Nothing. The high speed rpm stayed at about 15,500 or so at every stage.
PIc #5 shows the combination of feeler guages that were needed to measure
the gap
inside the small carb.....060"....
....acording to your theory, this is impossible. Acording to my theory, in which
"once the low speed needle clears the nozzle, it has no effect on the high speed
setting....in any way, shape, or form".
This turned out to be true, just as I expected....sorry. [
] The engine ran the
same on the high end, fron .008" gap to .060" gap....just like I said it would.
PIc #6 shows how I left the main needle the last time I ran it. Trust me on this,
it is a richened position....I don't shut my engines off at a full peak setting. Let's
call this a 10:30 setting, shall we ? This measured two turns, plus two clicks.
Pic #7 shows the position of the main needle at full peak with the gap at .060".
Guess what ? It is set at 1/4 turn
leaner than the .008" setting !!
As any tuner knows....when you enrichen the low end (opening the gap) you
will probably have to lean out the high speed.
Pic #8 shows the way I left the needle...richened, like I did before. The setting is
1 and 7/8 turns out....with the .060" gap.
This setting is 1/8 of a turn away from the initial setting (richened) of two
turns, plus two cliclks.
Sorry, my friend.
FBD.
