[Warren Seale]

Dear fellow Firebird fanatics,


I am Pim (20) and I live in the Netherlands. I’m looking for a set of headers for my 1980 Pontiac Firebird, which has been swapped from the original 301 to an Oldsmobile 403 (because, well... the 301 just didn’t cut it).


The issue I’m running into is that I can't seem to find headers specifically listed to fit a 403 in a 1980 Firebird chassis. However, I do see several options listed for the 403 in a 1979 Firebird. So my question is:
Is the chassis (or engine bay layout) of the 1980 Firebird the same as the 1979?
If so, I’d assume I could go ahead and order headers made for the ’79.


I’m open to both long tube and shorty headers — I’m not picky — as long as they fit properly and aren’t the heavy cast iron manifolds.


Any advice, experiences, or part numbers would be greatly appreciated!


Thanks in advance,
Pim

If you go with the Thornton manifolds (not headers) you will need to double up on the exhaust gaskets. This is because the 403 that is cast into the block on the right side slightly keeps the manifolds from mounting tightly to the head. Otherwise the manifolds fit well.