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In the specification section for 56s, the listing for distributor for senior cars is incorrectly listed as a delco 1110865. That was the first distributor used early in the run; because it gave problems with pinging it was replaced/upgraded to the delco 1110880. Timing specs differ for these units.

The manual specs are for the later unit.

Might want to make a note of this if you have had pinging issues......

Good to know. Not surprising though given the 10.0:1 CR of the 56 374. With gas octane available in the 60s though, it wouldn't have been a problem. With gas octane available today, it would probably be a problem.

Craig

Quote:
Unless my eyes deceive me, I see NO error in the 55-6 shop manual.

Distributor #1110865 and the respective specifications shown in the shop manual for the 5680 chassis ARE correct for those vehicles built prior to March 5, 1956 - UNLESS they have been converted to distributor #1110880. A bulletin on this matter advised of a kit for field service, which also included a new number identification plate to be installed on the distributor housing for future service and provided the specifications for distributor #1110880.

However, that conversion kit was ONLY to be installed in the field when a condition of engine detonation (ping) was encountered with premium gasoline. It is entirely possible, then, that some of those "early" 5680 cars still have distributor #1110865 (that is, if owners did not report a problem).

Meanwhile, Delco distributor #1110865 went on to be used in production on the 5640-60-70 chassis as a substitute for Auto-Lite equipment - also effective March 5, 1956. So, the shop manual specs for #1110865 are also correct for those models (like my dad's Exec). However, a second conversion kit was released, on April 5, 1956, but only for those cars built prior to March 5, with Auto-Lite equipment.

While any mechanic worth his salt ought to know enough to check the unit identification numbers prior to service, I will admit that they might not have had access to the updated service information. However, this information can be found via the topic of "Detonation..." under the Engine section of the 1955-1956 (55th-56th Series) installment of this site's exclusive Packard Service Index. Document links are provided for each topic and each of the relevant bulletins are available for download (and printing) - for FREE.

Yet, as someone else noted in another thread, decades old specifications might not be quite so compatible, now, with so much ethanol in modern fuel blends.

I have some distributor issues at thie moment; to me this news was a welcome bit of clarification.

I would not want to buy the older model as a replacement....no matter what my car started with.

I've tuned 374 engines with both the 865 and 880 distributors. Unless you've got a car with a peculiar appetite for gasoline or live in exceptionally hot and hilly country, you can tune with either distributor to give fine performance.

Have you gone back and read STB 56T-14?

That's what started me here....

There are no differences in point gap, base engine timing, and dwell angle specifications between these two distributors - except for the added recommendation in the bulletin to retard base timing to 7- or even 5-degrees, if needed.

The real difference between the two distributors lies in the advance curve. The centrifugal advance specification for #1110880 appears to be somewhat retarded compared to those of #1110865, while the vacuum control appears to be more advanced.

Changing the advance curve is not part of a typical tune-up. It's not a simple matter of adjustment - hence the need for a kit, which involved replacing the complete mainshaft assembly and vacuum advance control unit.