exhaust manifolds

[ahab.bligh]

Ahoy,
I have a set of exhaust manifolds that I am trying to identify
they belong to a small block 318/360. The manifolds have 2 1/4"
i.d. outlets the casting numbers (if that can help) are 53009377
and 53009376. I was told that they flow better than stock
manifolds for a marginal performance gain, If used with a better
flowing "y" pipe or duels, they help alot.
Any thoughts?
Thanks

[wh22366]

Back before I could afford headers for the small block 283 chebby I ran, I used a larger outlet set of iron manifolds designed for a 327. It did make my rig breath and run better. Here's what I'm thinking.

The outlets are 3/8" bigger diameter than stock -- a decent increase. Replacing or modifying the stock combo cat/y-pipe to fit your new manifolds is a bit labor intensive, but not impossible.

I'd probably try it If it was my truck and had the manifolds as I'm set up to do the fab work. If it gave me no seat-of-the-pants increase, so what. I'd have learned that it takes more than outlet diameter to launch a 4400 lb truck (my chebbie weighed 1000 lb less).

I put a set of Gibson headers on my '96 Ram 5.9. Two hours. Took longer to chase the bolt holes in the heads than it did to bolt them on. And a change you can feel.

Let us know if you try it and like the results. :D