I recently acquired an Edelbrock FM 255 dual quad manifold with Edelbrock 1404 carbs. As usual, I did not do my homework prior to buying, although I got it fairly cheap. I have since found that the FM255 manifold was designed for small port heads as found on '55-'56 y-blocks. It was replaced by the FM257, designed for use with large port heads as found on '57 and up y-blocks. Will the fm255 work on large port heads?

When Injustice Becomes Law, Resistance Becomes Duty

For street use and the "WOW" factor, it will work fine.  For all out HP with a big engine, it will lack a little compared to the 257 at higher rpm.

John - "The Hoosier Hurricane"

I had my stock 255 and stock 257 on Ted's dyno last year using the same 500 cfm Edelbrock carbs on both with the aluminum heads and there was a 23 hp difference. I will also add that I ran the 255 for over 25 years, many scrubs passed thru that intake.

  Vic Correnti

um..........What's a scrub?

When Injustice Becomes Law, Resistance Becomes Duty

GM product!

  Vic Correnti