Number to thousandths of an inch, please. I've been all through Redlines site, and can't find what I want.
Number to thousandths of an inch, please. I've been all through Redlines site, and can't find what I want.
Or, I suppose, just the math. A 32/36 has a 140 main jet, which is .056"...so what does the number mean?
Modern gas needs bigger jet.
I don't know that such a thing exists - at least I've never seen one. Braden notes that Weber jets are marked after they are drilled and tested for flow, which suggests non-standard sizing.
Which weber carb?
Also Main jet, idle or accelerator pump jets?
This might help though:
http://www.piercemanifolds.com/category_s/393.htm
32/36 DGV, main jets. I would presume the number/size should be common to all the different jets and air correctors, unless the numbers really are just a random selection.
I thought the jet number was the orifice size. So a 140 would be 1.4mm, a 165 would be 1.65mm, and so on.
Guess I'm wrong 
They do.
"Weber main jet sizing nomenclature refers to the flow rate in hundredths of a millimeter (0.01mm). A 150 main jet, for example, flows the same as a perfect hole with a 1.50mm diameter. Larger numbers make the engine run richer from off-idle to about midrange RPM. Jets are sold individually."
What are you using the 32/36 on? I've got some jet maps for various cars the 32/36 is popular on, and could possibly give you a ballpark starting point.
I have the starting point, but its based on real gasoline, not the alcohol laced swill we have to burn now. B20 Volvo, 140/135 mains, and it had a horrible lean surge. I used my torch tip drills, and took the primary main from .055 (1.4mm) to about .062. Its almost perfect now, but still has a wee lean surge in certain conditions. I know its a sin to drill jets, so I thought I'd order some, but didn't know the sizing.
Not sure why I didn't think metric. Its Italian, ferchrissakes.
Something in the 160-170 range will work, and I think I'll jet the secondary about the same.
Thanks.
Don't forget to look at the air corrector size, that will fine tune the air/fuel ratio, which seems to be what you're trying to do. To tune a Weber carb you really should have the book that explains their operation.
I'd step down an air corrector jet before doing anything else. Fuel jets affect certain rpm ranges and throttle positions where as air correctors affect a broader spectrum.
Also, what psi are you running to the Weber? They like 3.5psi. And timing is normally advanced at base to between 12-15 degrees and 33-35 degrees all in at 3000 rpm.
In reply to subrew :
Subrew, you have a map for a mazda 2.0, like an MA or a VB/VC from 1972-1984? No miata 1.8s the only certain I can find is for a smaller weber carb model
In reply to Streetwiseguy :
Not a sin to drill jets if you are trying to get a close range of what you need. I have a bunch of small mains I use to drill out then I can order a couple close to what I drilled to.
The problem with drilling jets is that the diameter of the bore is just one of the factors that affects flow. The length of the bore, surface finish and the entrance and exit conditions also play a major role. As a result just running a drill through the bore doesn't produce a linear change form one size to the next. In fact, it's possible to drill a jet that has a nice chamfer on the inlet and outlet and end up with a lower flow from the changes to the inlet and outlet conditions and the fact that the effective bore is now longer.
In reply to 02Pilot :
Idk if they mark them after they flow them as you can buy a Weber calibrated jet thingy that looks like a long tapered skewer that has graduated numbers on it. You put it in and where it stops is what jet you have and that is determined by the ID of the jet. Holley rates their 5200 carb jets (weber like) differently as I got a 167 fuel jet and it's pretty small, probably like a 50 or something in Weber speak.
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