the AEM fpr comes w/ 3 orifices: black(.100), silver(.150), and gold(.200). which one should I run w/a 255 fuel pump, siver or gold?also which pump is best Walbro, BBK, or other?

 

go with the largest one.That pump will flow more so it can use the extra flow back to the tank.if you go to small it won't allow you to lower your fuel pressure enough. you can always raise it if you need to...

 

LOL, best thread topic ever!

Free bump for you

 

I love the black orifice! Once you go black, you never go back. It's a little tight, though.

Seriously though, start with the black one and try to lower your pressure to the point you want. If that doesn't work, then move up to the next size. I had the gold orifice on my car with the Walbro 255lph HP, and it was difficult to adjust, then it started to make this annoying clicking noise caused by the diaphragm fluttering in warmer weather. I could feel this by putting my hand on the back seat above the fuel pump. I thought my fuel pump was toast, but since switching to the silver I haven't had this problem. I'd like to give the black one a try, just to see how low it can go with the pump I have. I finally spoke with a knowledgeable tech at AEM and he mentioned he and a few of his friends use the black orifice with a Walbro 255lph HP, 720 injectors and nitrous, but I'm pretty sure the 720s help relieve some of this pressure!

 

K so far I've heard the smallest (black) and the largest (gold), now I'm stumped. an other opinions to raise the tally?

 

No, I was told by AEM to start off with the stock black orifice to see if you can lower the pressure. If that doesn't work, then try the silver, then gold. I'm not suggesting that the black is best for your application. From what I was told by AEM, the gold orifice is used for pumps much larger than the Walbro. We're not talking permanent modification here. Do you know where you want your pressure to be? Throw it on, idle it, remove the vacuum hose from the intake and plug it, then try to adjust to where you want. My guess is that silver will work for you.

 

im running a silver aem fpr with a walboro 255 lph pump...........no problems over here

 

I'm runing the largest one with a holley 255lph hp fuel pump