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Hello everyone, I’m new here and am wanting to know how to tell the difference between a 352 and a 374. I have a 1956 Executive and at this point haven’t been able to find ID numbers.

The Executive is in all aspects mechanically a 56 Clipper Custom and specs applicable for that model (5660 chassis) will be the same. If the engine is the original it will be a 352. 5660 specifications are in this Service Counselor.

Basically the Executive came about when Packard wanted a lower priced car as a Packard branded starting out model for "the young executive on the way up" to buy. To do this they needed something which was more inline with the senior Packard line styling that could be done fast and inexpensively. They essentially stopped making the top of the line Clipper Custom model on one day leaving only the Clipper Deluxe and Super models. With senior fenders, grill, trim, and name bolted on the former Custom model it was out the door as the new Executive model the next day. When the Custom stopped production the 5660 chassis designation was retired and Executive models were designated as being on the 5670 chassis as a 5672 Sedan and 5677 Hardtop.

For proof of whether the engine is original and a 352 or 374 you can look at the engine number in front roughly in front of but slightly under the oil filter. There have been notations that late production models changed the location to the front of the right head.

The Utica number is seen from underneath and will identify which model the engine was expected to go in when it was built at the engine plant. The casting number is at the rear of the block on top of the bellhousing and will identify the size of the block casting.

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The number is almost importable to see without some disassembly. On mine, I had the oil filter and coolant manifold off anyway but with those on I could not see it.

You'll need to get in with a rag and alcohol to read the vin off the engine. If the engine has lost its paint then it will be hard to read.

Example pic below of someone being drunk on the factory floor

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Thank you! I definitely have my work cut out for me. One good thing is that it runs and sounds strong but from what I have read …one thing says that 1956 only had the 374 and the next thing I knew everything said 352.
I hope to post pictures soon.

G'day Merle,
to PackardInfo.

I invite you to include your '56 Executive in PackardInfo's Packard Vehicle Registry.

Quote:

The Senior models, ie Patrician, 400 and Caribbean, had the 374 while the others including the Executive had the 352. I believe there was also a 320 that was used in the base Clipper Deluxe but that may have been only 1955 before the 374 was introduced.

The Clipper, of course, was a separate make so for most of the year Packard did indeed have only the 374 but then late in production the Packard Executive appeared which, as Howard pointed out, was based on the Clipper Custom so it also had the 352.

In 55 the 320 was used on the 5540 bodies (Deluxe and Super) and the 352 was on the Custom and Packards. In 56 it was 352 all Clipper + Exec, 374 all Packard.

Note that 55 and 56 engines, even 352, are not identical. 56 had higher compression ratios and there some other changes such as hardened clips for the valve springs that prolong life (IIRC).

55 C/R on all was 8.5 (claimed higher on Caribbean in ads, but service manual says they are all the same)
56 352's are 9.5
56 374's are 10.0

Also it wasn't uncommon for some 55's to end up with 56 352 engines in them over the years.

BTW what octane of gas do you use in it?

Thank you to all the replies I received and the information you all shared is priceless. Other than the ID# stamped on the engine, is there a noticeable difference between the 352 and the 374?

I bought my 56 Executive running and driving up and down the driveway on a very small auxiliary tank under the hood. It has not been on the street due to needing brakes gone through plus restored. What little I have ran it has been on 87 octane.