I have a line on a pair of the later Exhaust Manifolds with flat Tops. Are the Outlets bigger than the 56 Style? In other words will my existing Pipes work with later Manifolds or would I need to have the Pipes modified to work with later Manifolds?

  

The outlets are the same size on both style manifolds.

John - "The Hoosier Hurricane"

I have a set of 57 exhaust manifolds if your interested, make me a offer. I'm in Connecticut.....Lou  

Thanks. I am in Canada and found these on Marketplace local. 

  

John what is better about the 57 Manifolds if the outlet is same Size as 56 Ones? Worth changing them?  Rebuilding my 292 and replacing all Valves with New Ones and the Intakes are the bigger Ones used in 57.  Thanks!

  

Here’s the link to the test Ted ran. Not a ot of difference, and this test on his dyno mule and open exhaust.

https://www.eatonbalancing.com/2021/01/17/ford-y-block-exhaust-testing/

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

Well, here's the thing ... 

The outlet(s) sizes are the same but cataloging calls for different inlet pipes between a 56 and 57 (naturally).

Are the outlets positioned the same or will you have to have inlet pipes made to fit the transition?

For what little gain the dyno results showed, is it worth it, especially if retaining the 56 cyl heads?

This is a driver (survivor-restoration) and no HP involved?

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Depends on your situation. is there anything wrong with your current manifolds, do you want to get some more power in the future, are they 57s cheap? Within reason increasing power usually has other benefits along the way which could be nice although im not sure you would have a quantifiable change with just the manifolds. Without going throught the articles again i believe their just improved castings giving a little flow. no downside to putting them on with teds example getting +3hp and +4ftlb average. although that was on a 322 with cam mummert intake and mildy ported g heads so who knows what it would do to a stock motor. ive always wondered what these parts would do with a stock motors.
Seth