For anyone with a 330 out there, what have you done for performance mods? Also, what jetting are you using for said mods? Has anyone removed the airbox lid then re-jetted for the air? I will start. I have a 2008 trailblazer. I installed a big bore kit from rick ritter, the 414 kit. I re-jetted to a 130 main up from a 115 stock main. I left the pilot the same. the jetting is still a little lean so I ordered some bigger jets for it. I also have a secondary spring from rick with a primary on the way

 

No one has anything to say about these 330s?


Well I took the airbox lid off this weekend. It made a huge difference in my top end! A little difficult to figure out the pilot settings but it all worked out. I would say removing the airbox lid and rejetting it was a way more noticeable power increase than clutch work. I ended up with a 42.5 pilot, which is stock, turned 2 turns out. Mine was only 1/2 a turn out because of the high altitude I live at. My main jet went from a 130 to a 150 and is still a little lean at full throttle so I have a 160 on the way. It’s crazy how restrictive the stock airbox is on this thing! Up 8 jet sizes and still going up. That’s a lot more gas witch translates into a lot more power.

 

Found out that my needle was what was restricting my fuel. A needle jet and needle off of a 1997 425 magnum will fit this carb because they are the same carbs. Helped a lot to get more fuel to the engine. The stock 330 needle has almost no taper to it and the needle is still in the needle jet partly at wide open throttle. So basically the gap between wide open throttle and the needle jet it only able to flow up to about a 145-150 main with my findings. And that’s with the needle raised. So I installed the magnum 425 needle and needle jet and it helped a lot but I and still lean. I have the needle raised all the way and a 180 main installed. Huge difference in getting the fuel to the engine. It needed it a lot the power difference is crazy I can’t beleve I didn’t do this earlier. But it’s still a little lean and the needle is to blame still I think. So I’m looking for another needle or might try to file and sand my stock one down. I will give another update when I finish. To anyone who has a 330 if you rejet for the airbox lid removed you will not be dissapointed in the power difference! Change the needle to the magnum one. Even if you just have an exaust and k and n filter in sure your engine would appreciate more fuel.

 

So I figured out my jetting. Just to restate my mods, I have a 414 big bore, uni air filter and the airbox lid removed. My jetting for the mods listed above ended up with a 47.5 pilot 1.5 turns out for the screw, a needle jet off of a 425 magnum, a Mikuni 4 series needle 4J13 and a 160 main jet. The needle is in the middle position. Runs awesome now no bogs anywhere in the throttle range. I messed with the slide in the carb a little for throttle response. I cut the slide spring, about a 1/4 of it off. I also drilled another vacuum port on the opposite side of the existing one on the bottom of the slide. It’s about half the size of the existing one. I’m not sure if it’s jetted perfect but it’s running really good so I’m leaving it. If I revisit jetting I will update you guys. Sometime this winter I’m going to buy a wide band o2 sensor and gauge so I will probably revisit it then to get it perfect.