Packard Forum Index » V-8 (1955-56)

Quote:

Thanks;
The '55 spec sheet shows:
"idle tube - pri .027" - sec .027"
but nothing for the '56.

So, bottom line, from the spec sheet, the '55 1x4 and 2x4 appear to be very similar carburetors; only differing idle adjusting screws, different choke cam, different choke adjustment.

However, the '56 2x4s are very different internally from the 1x4, correct?

FWIW, I'm running two '56 1x4s on my 2x4 intake on the 364" in my Studebaker pickup. I installed a wide-band O2 sensor and the cruise AFR is perfect. However, when backing off under compression or upon acceleration, the AFR goes full rich. The idle, low speed and secondary circuits certainly needed the modifications Rochester did to the '56 2x4 carbs.

jack vines

https://www.packardinfo.com/xoops/html/downloads/SC/SC-VOL29NO10.pdf

Didn't all 56 Rochester carbs have the removable assembly and the 55 did not?

There was also a campaign about making sure to steak something in the 56 carburetor or it would get sucked into the engine and cause damage.

Thanks to everyone who answered.

The friend also has a Cadillac Eldorado 2x4 intake and carbs which we hope will be originals. He's not certain as to the year, but initial research indicates the '55 Eldorado had two Rochester 4GC carburetors and the '56 and '57 had two Carter WCFBs. If that's true, then the '56 Packard Caribbean Rochesters were developed solely for us.

Now begins the research as to how same/different are the '55 Cadillac and Packard 2x4 Rochester carbs.

jack vines

There are stainless rings around the venturi and they had incidents where these rings worked loose and were sucked into the manifold. It is described in a Service Counselor and the required repair.
Carburetor: Primary Venturi Brass Rings, Rochester
loose, falling into intake - campaign 5688 STB 56T-23 (Zones only)
Carburetor: Rochester 4GC

Learn something every day. Some of you already know what follows, but I didn't until I examined many carburetors in detail. Like many Packard V8 owners, I've heard others say, "Yes, the Caribbean carbs and air cleaner are the same as the '55-57 Cadillac Eldorado.

As I dug deeper into it, none of the above is true. None of the Eldorado carburetors and air filter is a direct match for either the '55 or '56 Caribbean, which are different from each other.

1. In 1955, both the Eldorado and the Caribbean used 2x4-bbl Rochester 4GC carburetors, but the carbs used are completely different in design and operation of the chokes, the idle air control, linkage and several other small points. The air filter looks similar, but again is different in detail.

2. The two Rochesters used on the 500 or so '55 Caribbeans are a one-year-only design and different front and rear. For 1956, Packard had Rochester make new, different and special front and rear carburetors for the 560 Caribbeans built. AFAIK, they were never used on any other application. Rochester was accustomed to building literally millions of one design for GM, but they custom designed and built a few hundred for the Caribbeans.

3. The Rochesters used on the 3995 '55 Eldorados are also a one-year only design and for 1956-57 Eldorados used Carter WCFB carburetors. It may have been that no other GM brands used 2x4bbl Rochesters, but Chevrolet was going to offer the Carter WCFB on Corvettes 1956-60.

So the Packard Caribbean Rochesters are some of the lowest production 4GCs.

jack vines