Installed my ITR manifold on the B16 head and now when I put the fuel rail on and torque it down the injectors don't go all the way into the o-rings...you can still wiggle them around. Is there a different size spacer I need or something?

 

take the spacers out. You dont need them. I had the same problem. I actually got them to seat with the spacers in, then like a week later I try to start my car and it squirts fuel everywhere. I took the spacers out and presto chango! I have 450's now and they fit exactly the same as the stock injectors.

 

I just noticed that the hole that the o-ring goes into in the ITR manifold is deeper than the hole in the B16 manifold. Thats one of the problems for sure.

 

That is true also, the injector seals for the ITR are thicker. Use ITR seals, and take the spacers out.