Here is an alternative to using Big Block Chevy headers on a
Cadillac. Thanks to Charles for answering this post.
Q: What is the best and cheapest header to cut and weld on to mts'
flanges for 1.75 primaries?
A: From an alignment standpoint, the closest port relationship is
from the 460 Ford family. The same man designed both the Caddy
472/500 and the 460 Ford---and the engines are off just a little bit
in many respects. I would look for a decent set of 460 Ford headers
and cut them off and weld them on to your flanges. Do this while they
are bolted to a dummy set of heads and let them cool slowly and
completely before you unbolt them. I doubled up the flanges and have
never replaced the gaskets on my engine since I did. I use the copper
SCE gaskets that fit the ford 460 engine.
Q: Do the Fords align as well as the Big Block Chevy headers?
A: I tried the bb chevy, ford and mopar---the ford was much closer as
far as aligning or re-aligning the tubes for the new flanges. If you
look at the way a bb chevy exits and a 460, you can see what I mean.
I just went to my machines shop with a rubbing of my ports and asked
if i could rub the other heads and then i measured them and found the
Ford was the closest. It goes without saying that there are so many
more applications for the chevy headers...i.e. almost every car gm
made, but as far as the flanges go the ford was the closest.
Remember, my application doesnt care about the rest of the header
because its in a boat and the header configuration for the tubes
really didnt concern me as much. If you want a laugh, set a ford 460
head next to a caddy....they are very close.