Is there a reason You are not using a PCV Setup instead of the Draft Tube?

  

Looking at the intakes tested, there seems to be no clear correlation with port size and performance.  Large and small port are at the top end.  Large and small port are at the bottom end.  It's probably just a better port layout and overall design, or luck of the draw.

One problem with testing, as Ted has, is that the sample size for each intake is statistically insignificant.  It is impractical to track down enough of these scarce manifolds for the test to be statistically significant and probably also impractical to spend the time to perform the testing.  This means that if someone else acquired the same casting numbers for testing, but different manifolds than the ones that were actually tested, their list will be different, possibly significantly different.  Safe assumptions probably are that the top performers are better than the bottom performers but the ones at the top could be within margin of error and it probably cannot be said, for instance that the FM255 is better than the 257 with certainty.  More testing would be needed to find out if there is a trend and that's not likely to happen.


Lawrenceville, GA

I like the use of the smaller port manifold because of port velocity when the intake first opens. This is probably why Teds tests were good. Makes for great street driveability.  My dual quads use small base Carter WCFB's and I do not have a hood problem. I would however port match them as close as possible at least for the last 1/2" into the manifold, I like your choice of 465's, the forgotten Holley, and would drive on the rear for the the street. If they are mounted backwards the front one would be the one I'd try. I've never needed to run on both, I found that I had to also idle on the front one too along with the rear and only needed to squirt fuel into the front when the car/engine sat cold for a week. Any other time I do not touch the foot feed during any restart. 
Good luck...Any engine looks better with dual quads installed.

56 Vic, B'Ville 200 MPH Club Member, So Cal.

To fit the Edelbrock 573 three deuce manifold on my 292, I had to notch the top of the road draft tube. The back of the manifold kept it from bolting down.

Dist. does, not positive about draft tube but I think it will. (My engine uses the block side filter/draft.) 

"FREE SAMPLE"

I assume this means I won't be able to use my road draft tube and will need breathers in my valve covers?  I assume a stock 57 distributor will clear?

I'm pretty sure this would fit under the hood of my TBird.

The rear carb pad on the FM255 and/or 56 MERC ECZ-C ALUM intake sets back farther than the 56-57 FORD ALUM intakes. Just to let you know.

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I have a FM 257 on a 322" Y running two 550 CFM 4160s.  Works great on the street and strip.
Use 427 FE dual quad linkage and don't forget to connect the vac. secondaries together using the lids with the vacuum hose fittings as used on the 427 425 HP FEs! 

"FREE SAMPLE"

I think this would be a nice street combo.  It has the right look and the vacuum secondaries would keep the cfm down. I tried three old Holley 94s and I couldn't deal with those old carbs. I have a new 4160 on my car now.   I'm pretty sure this would fit under the hood of my TBird.  Anyone got a spare FM255?

The carbs I want to use are 4160

Here is a photo of the FM255 with either 4150's or 4160's. It looks like it will definitely take two 4160's.

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