Re: Engine and Head Numbers

Posted by HH56 On 2018/8/21 9:06:17

The cast in number on the head is a foundry number for a particular casting. Don't believe it was used for any identification purposes other than in the factory. After machining the casting Packard issued a different number which is the actual number you see in parts manuals with all the ratios for the different engines. I don't recall ever seeing a list of part numbers that could be machined from a particular casting but likely there was more than one. A different part number could be another ratio because of the size of the finished combustion chamber or could be as simple as a threaded hole drilled in a different spot where something would mount.

Postwar, Packard added to the confusion by authorizing dealers to swap heads from different engines and years to change compression ratios should an owner want a change in performance from factory specs. There is an article in one of the service counselors that describes the change in ratios an owner could expect by swapping a head. You can check the service index for the issue with the article if you want more info. With that in mind your car could have had one of the swaps made although it probably didn't happen much prewar. Since there is very little outward appearance to designate one head from another on most of the cast iron heads there is no quick easy way to tell which head is in your carl.