Re: Plug/ignition wires for 56 Packard 374 v8

Posted by BH On 2009/12/11 20:51:16

I'm not sure if there's an easy answer to your question.

Several years ago, I found a set of NOS Delco-Packard wires, at a swap meet and installed them on one of my '56 Patricians. My notes indicate that the box showed (perhaps in addition to a Packard P/N) a Delco short number - "448F". I doubt if these are still available in the aftermarket, though.

However, I can't recall whether those wires were for engines with or without the special ignition wire support brackets that were introduced during the 56th Series run. If you don't readily understand what I mean by that, check the Service Index on this site for 1955-1856 - under the "Electrical" category. The March, 1956 issue of the Service Counselor features an article on this topic, with dimensions for shortening existing/original wires, as well the factory P/N for a direct-fit set of replacement wires for use with the new supports. Otherwise, the plug wire dimensions do not vary by cubic inches of engine displacement for either year of Packard V8.

Though I never found a current set of direct-fit plug wires for the 1955-56 Packard V8 in the aftermarket, I did use a set of Filko wires, #3028 (for a '58 Chevy 348-cid V8, IIRC), just to get by on my Carib H/T some years ago. The straight boots at the distributor end could be slid up the wire and the terminals reused. So, I trimmed each wire to fit as I installed them, to allow for the incorrect 90-degree boots and terminals. However, because the Filko wires didn't have a steel core (as original), they had a tendency to droop and get in the way of the carb linkage. While I got by on those wires for a few seasons of limited use, I will discard them before I put that car back on the road, in favor of OE type. More on that later.

There's another factor to consider in seeking out modern replacement plug wires. As originally equipped, regardless of Delco or Autolite electrical equipment, Packard V8s did NOT use resistor type plugs or suppressive type wire to manage RFI. Instead, the OE rotor was designed with a carbon rod in the path to the cap terminals to suppress radio interference. If you don't have a rotor in hand, check the shop manual for an illustration. I suspect that using modern suppressor type wires in conjunction with an OE style distributor rotor could very well result in weak spark - though I've never fully tested that hypothesis myself. It is should be possible, however, to match up a rotor as used on earlier straight eights that does not employ such a carbon rod.

Yet, now that the correct 135-degree spark plug boots have been repro'd by Steele Rubber, I decided that, when the time comes, I'll look for the corresponding spark plug terminals and a roll of the steel-cored wire to make my own - using the Delco set I put on the Pat as a template.

Unless you've done or are contemplating some sort of HEI conversion, I don't believe that having sealed boots is that important. Using the correct spark plug terminal and having the right crimping tool IS. However, the wire terminal that fits into the OE distributor cap requires no special crimping tool. Also, the boot on the cap end of the wires and the for the coil tower (which may be larger), as well as the terminals, were a fairly standard item, IIRC.