Hello

I am in the process of building my first boosted engine. I have a good inline 250 chevy. I modded a Holley 2300 350cfm 2 bbl with .078 drilled pvcr's , jetted to 70 and running a 6.5PV, .110 needle / seat and completed all of the necessary Hanger18 mods. Also a modded Holley FPR for 1:1 referenced boost.

I will be running a GN T3 turbo from the original manifold and boosting through a carb hat.

***My question?? When boosting a modded carb, is it a two step process of tuning it right with out the turbo boost and then again when I have boost to the carb? It seems that when forced air is applied ( boost ) the adjustments will change when compared to a normally aspirated carb setup.

Also, do all of my vacuum ports need to be closed? two on carb and one on intake manifold?

Thanks, the board has been a huge help already

Shad in Nashville

 

Doesn't look like anyone else is going to answer and I'm a newbie here.
But here's my answers.
Tune as you increase the boost. Start off low and slowly work your way up. Using a wideband.
Vacuum ports need to be plugged on your carb.
How are you running your PCV valve? You may want to run it to your intake with a check valve.
Post some pics please.
Lee