so this seems like a dumb question, but this is killing me. i bought an OBX ceramic header for my 00 si however, i have a JDM b16a in there instead of the USDM b16a2. i can't get the thing to fit on the motor in my car (b16a) but it slides right on the b16a2 on the motor stand. is there any reason these two motors would be different? they both have the same casting numbers, pr3, and everything else has fit fine, why not this header? any help is much appreciated.

 

is it a 4-2-1 header or a 4-1 header? and are you having trouble just trying to fit it in the bay, or is it not mounting on the bolts at all.....

 

What do you mean? It doesn't line up with the studs on the head or it has clearance issues underneath the motor?

 

all Bseries headers will fiton the actual bseries head. but you might have clearnce issues or length issues. that vary from car to car and model to model and year to year. maybe there is a bent stud on the motor in your car now. have you driven the car with the motor in your car now, or did you just recently swap it. be more specific

 

i haven't driven it since the swap, i am about to adjust the valve clearance, then warm it up and time it. it has the stock manifold (from the a2) on it now. the header was ordered for a 99-00 si. the first problem was there was one stud that didn't quite line up. so i drilled out the hole in the header just slightly, and it lined up better, but then the down tube for the #4 cyl would hit a ridge in the block and not allow the flange to meet with the head. it is a 4-1, all the tubes meet in the same spot way under the motor, right before the 02 sensor. it is a really tight fit and it just won't go, but when i put it on my old motor, it fits fine. thanks for the help.