Originally Posted by
lilchill
msn was out from flush when i got...idles high....This has me baffled as my nova's with 3 needles all have the msn flush w/carb body.
Ok. So.. what you call the MSN.. is basicly like a receiver cup.
The LSN pointy part, goes into this.
When you are adjusting the LSN, you are adjusting how far into this receiver cup the LSN pointy part goes in.
How far the pointy part goes in, is what limits how much fuel comes out of the nozzle when throttle position is within the LSN spectre of adjustment.
The point of the socalled MSN is that you can adjust this jet nozzles position in the air stream.
Basicly what is happening here when you are closing this "msn", is that you are moving it inwards towards the centre of the carb, which will ultimately result in you pushing the LSN out of the carb once you go far enough in, but before this, you will get an excessively lean condition - same as as if you close the LSN too much in.
The fact that the screw head does not sit flush with the carb body has no bearing on it's function, as the function is not to sit flush with the carb body, the actual function happens inside the carburetor. As such your concern is basicly an obsessive-compulsive issue where you think it "must be flush", but really it doesn't have to. What it has to do is be adjusted in such a way that it works.
ANyway, once you push that too far in, so that it pushes the needle out, idle will be high. In fact I encountered another person who had done this very same thing, and it was leaned way out on bottom as a result of this. His was in fact two full revolutions in.
So pretty much don't mess with it if you don't know what it does, and certainly don't use external appearance of the screw head as a measure of adjusting it.