Packard Forum Index » V-8 (1955-56)

A friend is asking how to identify the correct Caribbean 2x4 carburetors. I did a quick search, but didn't come up with the thread on this I remember seeing some time back.

Yes, I did ask him if the carbs had the metal tags, but of course, they don't.

Thanks in advance.

jack vines

Hi Jack: Just one small feature that pops to mind is that the rear carburetor does not have a fast idle cam nor an idle speed adjustment screw. This is for 1956 but I believe the same absence of these features on the rear carburetor also applies to 1955. I could take a picture if necessary.

PS - my memory failed me, see next post.

The differences and detailed rebuild info for 55 Caribbean carbs is in SC 29 #6 and there is further info on 55-56 differences in #10. Here is the most obvious for 55.

On the 56 version I believe external is substantially the same as 55 but included are the other basic 56 changes such as removing the atmospheric vent and adding secondary throttle plates.

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An older post. The metal tags on the carbs should provide the confirmation you'll want.

packardinfo.com/xoops/html/modules/newbb ... um=8&post_id=205730#forumpost205730

Mike, Jack noted in his question that the metal tags are missing.

Thanks for the prompt replies.

I'm trying to tell him how by long distance and without the correct carbs in front of me.

The Service bulletin details the differences between the front and rear 2x4 carburetors.

What I'm trying to give him is what to look for externally to differentiate 1x4 from 2x4.

IIRC, the 2x4 carbs have 1-5/16" (1.300") throttle bores, while most of the 1x4 carbs on my shelf have 1.400" approx bores.

There's also a mention of the 2x4 carbs not having a secondary low speed jet. Can this be visually confirmed externally?

jack vines

Here are the carb specs. The Caribbean is in the red box.

It would appear that other than what is mentioned externally in that other SC article, there is not much difference in the dual configuration vs a single carb for 55. 56 has different bores and different jets.

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Thanks for the prompt update.

So, if I'm seeing correctly, the '55 1x4 and 2x4 are identical specifications and small (1-5/16") bores.

The '56 has different p/n and specifications for the larger (1-7/16") bore 1x4 and 2x4 carbs.

So, it's possible to visually identify '55 from '56, but not easily possible to identify 1x4 from 2x4 '56 carbs.

jack vines

Jack -

There is another visual cue.

On a 1x4, the fitting on the end of the choke air tube connects to a threaded nipple that's cast as part of the choke thermostat coil HOUSING.

On the 2x4s, the fitting on each end of the choke air tube connects to a threaded nipple that's cast as part of the choke thermostat coil COVER, which is made of cast metal (rather than the 'plastic' cover used on 1x4s).

I'm advised that for 1956 the single 4-bbl had a cast venturi but the duals had a stamped venturi cone staked into the primary venturi casting. Remember the service bulletin about the failure of the staking and the venturi cluster being ingested?