[2.7RACER]

doc18015,
The jets are sized metrically.
That is a 50 idle jet is 0.50mm dia.
A 60 idle is 0.60mm.
To convert to inches, 1.0mm equals 39.37 thousandths. Most folks round it off to 40 Thou.
Therefore a 50 idle (0.50mm) is equal to 20 thou.
A 60 idle (0.60mm) is equal to 24 thou.
A 45 idle (0.45mm) is equal to 18 thou.
Can you see the pattern here?
I have a set of very small drill bits for my Dremel calibrated in thousandth's.
I use the 18 thou to check my 45 idles. 18 is GO, 20 is NO GO.
Likewise mains 150 is 1.50mm, equals 60 thou.
180 air correction is 1.80mm, equals 72 thou.
I also resist drilling out the jets.
I'm fortunate to have a shop with a decent inventory about five miles away.
PMO delivers within a couple days, if I can't get them locally.
I have a small inventory, including some idles marked 45 that run as big as 55.
I always check jet sizes with the small drills, since I don't have a jet gauge.
I never believe the markings until I have checked the jets.