I have a l28 with mild comp cam 260s and running triple solex 44phh carbs. Here are my specs: 

outer Venturi 34, jet block OA , main jets 180, main air jet 220, pilot jets 57.5 

it runs pretty rich under the high load areas in the mid to high range getting AFR’s around 10s and even high 9s which is super rich. Do any of you guys think I should run main jets to say 160 or 155 or 150? I’m leaning towards 160 to try first but would like some opinions. From what I know the recommended from Mikuni for a stock engine is 150 for 34 Outer Venturi  Or 155 if you run larger 37 outer Venturi. Since I have a cam and full exhaust system I figured maybe a richer setting is safer. Thanks 

 

Edited October 17, 20195 yr by fairladyz432

@Mike Posted this great table:

 

Here is what you need for starting:

So your main is too large,and pilot is too large.  Reducing these will raise your A/F

 

Fuel pressure settings? 
 

I would drop air and main  

 

 

thanks for help 

 

I may stick with 57.5 pilot jets or go down a bit so I’ll have a leaner cruise and idle, as far as main jets I think maybe 165 would be good since I’m using 220 main air jets? Since recommended starting is 145 main jets and 200 main air jets. Difference is 55 in size. Does that sound right? 

I'd guess that'll still be too rich. The air corrector only leans it out at the top end. So if the stock advice is 145 main and you're mods are a mild cam and exhaust I'd be going 150 as the next step.

Actually you are very lucky to drive with a/f of 9 and 10!

JobBill is spot on!

Ok I’ll give the 150s  a shot. Do I stay 220s for the main air jet? 

It may go lean as the rpms rise (theoretical) but practically on Webers it mostly just leans all of the WOT run so I can't say on your M's

The pilot/idle jet is also too large, You may want to adjust after you sort the Main.

 

What is your idle a/f and cruise at 60mph a/f?

Aim for 13 for smooth idle, aim for 14.5 for clean idle

Aim for 14.5 for norm cruise. Aim for 16 for fuel efficient cruise.

 

 

From what I recall on freeway it was in the 12s during cruise and idle I was seeing 11.3-11.9 and sometimes go 12.5 so yeah I have to get close to 13.5 or so for idle and 14s for cruise. 

I'd take the idle jets down to 54.

Not sure if they have jets in 54 but there’s 55, 52.5 , 50 . Maybe a 52.5? 

Not sure if they have jets in 54 but there’s 55, 52.5 , 50 . Maybe a 52.5? 

Yes I'd go for that I think if that's the choices.