Is ECZ 9425B the correct intake for a 1957 Thunderbird?   I want to use this on my 1955 TBird 292 engine with a more modern carb

Yes.

John - "The Hoosier Hurricane"

I think you're going to need to get a '57 and up distributor, also, for advance purposes. 

Yes - and later carb will require a later (57 and up) distributor.

54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

Stuff you wanted to know about the ECZ-B manifold but were afraid to ask.

The ECZ-B four barrel intake manifold was first introduced in late 1956 for the 1957 models equipped with the 245 HP 312 engines.  The larger trucks also used this 4V manifold through 1964 on the 292 engines.  For the 1957 Ford/Mercury and 1958 Mercury models, the intake manifold had a vented air tube passing through the lower bottom side of the intake manifold to supply heated air to the choke.  Those tubes are problematic in eroding over time thus causing an exhaust leak either to the carburetor choke housing or to the outside of the manifold or both.  Those tubes are available new in a stainless steel version and can be replaced.  If not using a ‘hot air’ choke, then those two holes on each side of the manifold can be blocked to prevent a potential exhaust leak.  Starting in 1959, that tube was eliminated from the ECZ-B intake manifold as the air supply for the choke was relocated to a heat stove within the right-side exhaust manifold.

The early ECZ-B 4V manifolds did not have the engine firing order on them.  Starting in mid-February 1957, the firing order started appearing on the intake.  This is only important to the restoration crowd when date coding of the parts becomes important.

I have now dyno tested some of those stock ECZ-B manifolds in a back-to-back manner on the 312 dyno mule and have found up to a 6 HP difference between them.  Depending upon the date and the casting mold, there are some performance differences.  Both the casting part number and the mold numbers are located on the manifolds on the rear runners behind the carburetor flange.

It’s interesting that the ECZ-C dual quad 8V manifold was available for the 1956 Mercury models. Simple logic says that the ECZ-B 4V manifold was already designed and ready for production in 1956 and simply waiting to be used on the 1957 model cars.

The stock throttle bore size at the carburetor flange is 1.500”.  The replacement 465 cfm Holley carbs for the 1957 Thunderbird match this perfectly.  To use some of the newer aftermarket carburetors, it will be necessary to either enlarge those bore sizes or use a carburetor spacer that accommodates the throttle bore size of the carb that’s being used.  The throttle bore size of most 600 cfm carbs is 1.560” while the throttle bore size for 750 carbs is 1.690” and 1.735” for 850 carbs.  In a perfect world, it’s desired to not have any ‘ledges’ in the flow path.

For additional performance, there is an advantage to machining the four holes at the carb flange to a two-slot configuration.  The slots are made larger to accommodate the later model carburetors. This by itself is worth ~6 HP without any other mods or porting to the manifold.
 

 

Lorena, Texas (South of Waco)

Just a note - 

The 4V INTAKE MANIFOLD for the 1957/64 272/292 TRUCK was slightly different than the PASS CAR ECZ-B.

I have never seen one (or realized it when I saw/worked on one).

I would think the difference(s) would be for the governors and related.

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... hmmph ...

This brings up another little factoid I have been wondering about.

The carb pad throttle bores on the ECZ-B are 1.5in (and I assume on the 55 and 56 4V intakes also) and if one wants to go with a larger carb either has to modify the carb pad throttle bores (which will affect resale value of the intake) or use a step adapter.

The step adapter throttle bores do not not perfectly align with the carb pad bores but has a mis-match.

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The ‘55 heads will have smaller intake ports.  You may suffer some flow restriction/turbulence issues, though how significant I wouldn’t know.

6 VOLTS/POS. GRD. NW INDIANA

I seem to recall Dan Jessup realizing a performance gain when using the ECZ-B intake on the earlier (smaller) heads. You might ask him. 

Kultulz...seems like you'd have to get maybe a 1" thick spacer with 1.5" throttle holes and gasket match the the holes on the "top" side with a die grinder.