Mazda 12A Weber Jet Sizes and PSI

R

remsport

Member
What jets are best, as a starting point, for Weber 48IDA with 40 mm chokes? And what should I expect from upsizing from 38 mm chokes?

Also, what is the optimum fuel pressure?

REMSPORT Rich
(formerly Racin Rich but can't get that username to work)
 
From memory without my setup sheets.
F11 tubes
135 AC
250 mains

My rear main is bigger, could never keep the egt's under 1600 with the 250, the AC might be 120 in the rear also.

Pressure at 4.5, with a carter pump. Yes I am a little rich, but she does run good. I figure the 42mm chokes will work fine with my current setup. In the next issue of Fastrack were going to get the 42's, and less weight. Now if we could only get the Miata suspension :)
 
Thanks for the heads-up on the 42 mm as I was unaware of that upcoming change.

Also most of the fuel pressure gages I've found are 0-15 or 1-100 psi but since the 12A pressure would be in the bottom 1/3 of the 0-15 gage I'd like to use a gage with a lower range. The low pressure range gages that I have found in industrial catalogs are 2 1/2" or 4" diameter which would be too large for underhood mounting. Does anybody know of a source for a small dia. low pressure gage, ideally 1/1/2" dia and 0-6 psi?
 
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