Packard Forum Index » V-8 (1955-56)

I was wondering if a 55 caribbean with single carb could be changed to dual carbs or is the motor built different and what are the differences.

All 55 and 56 Caribbeans came standard with dual carbs. There were no modifications to the engines themselves to accept them except possibly the distributor advance curve.

If you are going for a show car, by all means you will need them. If the car is a driver, leave your 4 bbl alone. In any normal driving situation the 4 bbl will be more tractable, servicable, and deliver 95% of the power.

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All 1955 and 1956 Caribbeans came from the factory with dual quads. If your 1955 Caribbean has a single quad... somebody along the way removed the duals. Seen this done a lot over the years when people thought it would save money or they didn't want to have two carbs rebuilt when they could get by with one.

As for modifications to the engine... actually there was indeed a modification to the engine to accept dual quads and this is apparently forgotten today. The breather pipe on the galley cover under the rear of the intake manifold for dual-carb engines was flattened on top. The reason was to clear the extra bulk of the rear underside of the dual quad manifold.

Many have been the times when I have heard from someone attempting to install dual quads on an engine that had a single quad. "The manifold won't fit down to bolt it on the engine!!!" is the usual complaint! People think there is something horribly wrong when in fact it is simply the wrong breather tube hitting the underside of the intake and preventing it from seating properly.

I have seen people try to king-kong the dual quad manifold into place by tightening the daylights out of the manifold bolts with the wrong breather pipe under it. In one case, the poor fellow could never get his intake manifold gasket to seal and had huge leaks all around the gaskets. So these things can...and have happened.

Now IF your engine was the original, chances are the correct flattened breather tube on the galley will still be in place. However, if your engine has been swapped out, the breather tube on the galley cover is likely going to be round with no indentation. No cigar.

In THIS case, you will need to remove the galley cover and either replace it with a correct one... OR carefully flatten the top of the breather tube far enough to clear the dual-quad intake manifold. Otherwise it won't bolt in.

Since Leedy added a bit of Packard dual quad trivia, I thought it fit to add another.
If you attempt to install the oil filter canister from the single quad engine to your dual quad conversion, the lines from the canister used on the dual quad engine will encroach on the leading edge of the front carb and make you wonder what you are doing wrong .

The answer is that although the cannisters look identical the holes in the canister for the dual quad are drilled slightly lower.

This is probably not a commonly encountered problem for those who start with an assembled car where all lines are as originally installed, but starting with a basket of parts removed by third parties from unknown cars....and unlabled can lead to hours of fun
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The power steering pumps for the Bendix and Monroe units are similarly identical to casual inspection but are not interchangeable .
RJR

Sorry Leeedy---missed that third e again.

Leeedy Quote:

This is not a big deal, but it is a lot easier if the engine is on an engine stand, as I did on my Panther engine (originally 56 Clipper 352, now 374).

Others should thank you for bringing up this simple option.

Craig