Pretty much the same (5 - 7 sec). The pinch test gets you in the ball park for the bottom end tune. Perhaps the most important thing when doing the pinch test is setting the idle gap by the amount the motor spikes up in revs when you pinch off the fuel line.
As you know, the LSN is directly connected to the throttle slide, so getting the idle gap set right so the throttle slide (and LSN) are correctly positioned before you start tuning is paramount.
If the motor spikes up quite high in revs when you pinch off the line, you need to reduce the idle gap. What you want is a slow steady rise in revs (only 500 rpm or so) which will indicate the idle gap is correct. Now that the throttle slide is set in position you can tweak the LSN to get the 7 sec period before the motor dies, which indicates how rich or lean the LSN is set.
7 sec will put you in the ball park with a short or long needle carb.
I have found at 7 sec the LSN is still a little rich, but that is good, because when you set the HSN you invariably need to lean it some to get the crisp top end you require. Leaning the HSN will effectively lean the LSN too, so after you have set the top end, your 7 sec bottom end which was a little rich, will now be pretty close to spot on. Just fine tune if required.
The biggest difference with the short and long needles is the amount you will need to go in from flush on the HSN.
The long needle requires the HSN to be rich enough (flush or a couple of hours in) to let sufficient fuel past the longer needle which stays in the receiver jet even at full throttle - which is why you adjust the HSN to cure the lean bog on this carb as opposed to the LSN like normal.
The short needle will see the HSN some .5 - .75 turns or more in from flush, as on the short needle carb the HSN is totally controlling the amount of fuel the motor gets at full throttle as the LSN will have come completely out of the receiver jet at around 2/3 throttle (completely different to the long needle set up).
Jeez - sorry if it seems like I am rambling guys, but there is no short way of explaining this I don't think. Apologies to those who have read similar posts before, but hopefully people will read this and the light will come on for some of them as regards some aspects of tuning the different needle carbs.
Cheers
