I got Hooker 2460 headers and a Hooker y-pipe that is designed to fit those headers.
Thought it would be a simple job but for some reason the y-pipe is always half an inch off from one of the header collectors.

What am I doing wrong, or should I just force them on somehow? Also, bolting the y-pipe on while trying to hold it in place is a real pain.

I even considered installing the headers on the y-pipe first and then bolting the whole assembly on the cylinder headers.

 

Did you try flipping the Y-pipe over? just a thought, past that I have nothing.

 

Y-pipe fitment can be extremely tight and is very precise, with little tolerance for adjustment, so the pipe has to be well-aligned to both sides when raising it into place, which is difficult with only two hands, especially if the car is on jack stands, and you're laying on your back underneath it.

Get one side very loosely bolted so you have some movement to play with, align the other side and try to get it loosely bolted too, then tighten each side a little-at-a-time to slowly raise both sides together, while making sure the crossover pipe isn't hitting anything and is going up into its proper location. That worked for me when I found myself having similar issues.

 

Are you sure that y pipe is meant for those headers? I know Hookers 2055 come with a Y-pipe but I thought those hookers do not.

 

Here's the y-pipe, it's the correct one as far as I know:
http://www.jegs.com/i/Hooker/520/16767/10002/-1

Yup, that's how I'm doing it.
Is there any chance my headers are bolted incorrectly and there's like a 1 millimeter slop and this is causing the y-pipe to not fit? They're bolted as tight as I could get them but I can still see a gap with bolt threads showing between the header and the cylinder head which worries me.

In any case, thanks for the tips. I'll try them out tomorrow.

 

Your correct that is the correct Y-pipe for your headers. i would take everyone else's advice and also try to get a extra set of hands to help you hold that thing up, always easier with 4 hands, maybe a jack.

 

Had a similar issue with their 2055's. Sent it back and got another 1 that fit better.

 

How perfect does the seal have to be?
This is the best result that I could get and there's a slight gap, about as thick as my thumbnail.
I torqued the bolts many times as an effort to get a perfect result but the right hand side would always end up looking like this.

http://aijaa.com/img/b/00485/13104059.jpg

 

Got to be flat to seal. Looks like you could easily shape the flared flange with a hammer
The 3 hole Hooker flange is a POS with no support between holes. I welded some flat stock between the holes on mine to give it more clamping force

 

you don't want any gap between the flanges or it will leak. When I put my 350 in I was convinced I had a tick in the lifters but it was just a gap between the flanges. Also helps to have another person and loosen the headers