Hello everyone looking for help tuning a 12a street port with a weber 45. Dont want anything crazy just a cruising car with a little bit of jam. I feel the acceleration hesitant and a cut in power at 5000rpm in 3rd gear. (Fuel delivery is good new lines filter and inline pump) can anyone help me out and take a look at my jet sizes make any suggestions.

12a street port stock ignition
Full RB exhaust, inline fuel pump regulated to 3.0 psi, I have the vacuum advance hooked up. ( know alot of people dont run vaccum advance with a weber carb but I found it ran smoother at cruising)

38mm venturi
4.5 aux Venturi
195 main
175 air
f11 emulsion tube
f9 .60 idle
50 pump jet
50 pump discharge

 

Change F11 emulsion tube for an F7 and main jet to 185. How many feet above sea level is your location? Do you have wideband AFR gauge?

 

I have a AFR gauge only led, about 80 meters

 

Not that far above sea level,what does AFR gauge say?

 

It says rich idle and rich cruising, when it cuts at 5000 rpm it leans hard.

 

#s

 

How related are weber 45s to 48 IDAs? I know having a wideband makes the process pretty straight forward.

 

My AFR gauge is only an led bar does not display numbers

 

Well, if it works with a wideband o2 I think the led bar will be ok if you understand the how many leds or the color means what. As you drive make note RPM, load, and how many LEDs there are then with that you can start swapping out jets and so on in relation.

 

Okay thank you.
so I should switch F11 emulsion to F7 and 195 main to 185 for starters? Does everything else look okay for my jet sizes?
38mm venturi
4.5 aux Venturi
195 main
175 air
f11 emulsion tube
f9 .60 idle
50 pump jet
50 pump discharge

 

That is strange, with those jets, you should be able to run, even if lean or rich somewhere, my jetting is quitre close to yours and I have roughly the same setup.
Is everything OK in 2nd gear?

If yes, it looks like a fuel starvation... If it is not the fuel pump, then the float level or something else. What is your fuel pump? Fuel filter?
3 PSI might be a little low, you can also ty to raise to 4.5psi (300mbar in metric, I've seen it recommended a few times - can't remember where but that is what I run).

 

the two carbs use the same jets and some other bits, both 2 barrels. wideband does speed things up, but process is the same

this is ok, it will work fine as is for low load stuff, for WOT it is a little slower. you start fully rich, so the car doesn't run, and then lean it out until it does run, and then pulls hard, and then maybe 1 jet richer. with a wideband you can be more targeted

 

Yes idle, first and second no cut in fuel and can rev high rpm, only 3rd high rpm it cuts fuel. I will check my float and increase pressure.

 

that is a classic symptom of not enough fuel pump. if you do a volume test, you put the fuel hose in some liter or more sized container that you can measure the volume. i've got something that was meant for juice, its labeled in Millilitres.
you put the fuel hose in there and run the pump for 30 seconds (if its big enough a minute).

the stock pump should do more than 1400cc/minute (~700cc in 30 seconds), the competition setup is 3000cc/min.

 

I have an aftermarket inline pump 60 GPH regulated at 3.5 psi

 

but does it deliver 60 gph? i have a 72 GPH pump in my car, and it delivers about 35....

 

Found my fuel issue guys, my float was not adjusted enough. I now have a hesitation and popping noise sort of like a popcan under the hood at high rpm any ideas? Thanks everyone for all the input

 

I have an issue with my car going lean. So hears the problem. If I rev the car at a stop just half throttle it lien out hard, I'm not stomping on the throttle either, I know you cant do that with a carb. it will also lien out hard after 5000rpm. The weird part is if I gently lean into the throttle and roll into it, either revving or doing a pull my AFR will maintain right about 13-13.5. I just did some maintenance and put in a new filter and pump, cleaned out the gas tank etc... so everything fuel wise feeding the carb is perfect. Any help would be great, thank you!.
I know this is a streetport thread, but Im heaving trouble finding info. I have a stockport 12a