Anyone in the Chicago area that has experience or familiarity with tuning carbs? specifically mikuni PHH style?

its an S5 NA 13b in an S4 car with large streetport and some other goodies and I got it real close since it idles fine and handles transitions well but I wanna fine tune it some more for heavy throttle, higher RPM operation.

yes I have a wideband

 

So whats questions do you have about getting it dialed in? Are you unable to get the AFRs that you want?

 

basically.

it goes too lean under WOT conditions but I haven't been beating on it since I'm still breaking the engine in but low rpm I try to floor it or give heavy throttle it leans out a lot and stumbles like its getting starved of fuel.

my idle afrs are around 12.8:1 but with no load just holding the RPMs at 3 or 4krpm it is around 11.1:1 so it just pours out black fuel rich smoke

this carb I was told has already been jetted for a 13b streetport but I'm not sure of any of the sizes of the jets or emulsion tubes.

 

That would be the first place to start looking for problems. You should also check the float height. Are you sure that the fuel pressure is correct?? I needs to be between 2.5-3.5 psi of fuel pressure, just like webers and dellortos they are sensitive to fuel pressure.

Ryan

 

I bought it off someone who had it on their 13b streetport and I hear mixed things on fuel pressure, some say have it 4.5psi others say between 2.5-3.5psi so right now I have it at 4psi. I have gauge at the regulator inline to the carb which only several inches away.

Is there a float adjustment on it? I see a brass fitting on there with a flathead but I'm unsure. I have a mikuni phh manual but some of the pictures are kinda lousy.

 

that and it doesn't like to start when the engine is cold.