Re: The Second Packard "Twin Six"

Posted by PackardV12fan On 2008/9/21 11:54:46

regarding MERLINS

Sorry - Merlin aircraft engines, and the details, are way beyond my pay grade. I am in the situation John so often finds himself - really dont know what I am talking about in terms of personal hands-on knowledge in this area; can only repeat what I have read.

I dont know anything about your discussion on rod bearings. Differs from what I read. My understanding is that the copper-lead precision "insert" type bearing was developed jointly by Federal Mogul and Packard, and tested on the Packard High Speed test track. Wasnt there.

They came up with the idea of the silver-lead substitute, not because of strength issues, but because of chemical reaction issues, solved later by the development of additives to motor oil. There were some erosion problems with the copper-lead insert with dirty engine oil that were solved with the silver type. In fact, Packard Stores even offered, for a short time, for automotive use, silver-lead insert bearings. Again, once engine oil evolution with new additives solved this problem, that ended the need for the silver-type insert. I dont recall seeing them offered in the Packard parts books out when I was a kid working in garages in the 50's.

Again, "I wasnt there", in the 1930's and, again, like John, can only go by what I read.

To my knowledge, there are no silver-lead inserts offered for general use today - my understanding is the copper-lead bearing is still the "standard" for extreme duty service.

With much shorter strokes, the extreme strength of the copper-lead type bearing isn't necessary in ordinary service. I know some heavy duty diesel engines use them, not sure about lighter duty truck and industrial applications.

As for developing a way to produce reliable mass-produced over-head valve, over-head cam "cross flow" type motors, suggest you review the evolution of the Packard Liberty during World War I. I gave up storing back-issues of the various publications from which I get my information (on subjects like this, where I DONT know what I am talking about from personal experiece), so I cant provide you with specific reference sources.

Perhaps someone in here who DOES know what they are talking about ( as to the technical details of Packard aircraft engine evolution), can fill us in. I read somewhere that some parts will interchange between the English and American "Merlins". Somewhere I read the English motor had to be completely re-engineered to eliminate failure-prone areas, and set up up for American tooling.

As for super-chargers, Packard had developed them during World War One. Seen photos. Wasnt there either.