Packard Forum Index » Pre-War (1899-1942)

Hi,

I was looking at a picture of the engine of my Packard Twelve restoration project. The engine number is stamped with a star, then the number 905820, then a star, then what looks like the letter A.

*905820*A


Can anybody tell me the significance of the letter A at the end?

I think I remember seeing a thread on here once before about an A at the end of an engine number, but I wasn't paying attention at the time, and can't find it now...

It may not be important, but it does have me puzzled. If you know what it means, please let me know!

Thanks,
Ian

Attach file:

---

  (99.60 KB)

It would be really nice if someday an index to all the engine suffixes surfaced, I've never seen one. An "A" suffix would have an entirely different meaning from one year and/or engine to another; for example one year and on one engine it might mean a change from a forged to a cast camshaft, another year the same letter might indicate a change in valve guides or some other entirely different feature. I'm uncertain of the meaning of an "A" suffix for 1937 Twelves but think it might be a running change in piston type. The 1937 Twelve started using a tin-plated aluminum alloy piston with a simple expansion strut, and by 38 the Twelve used a 0.006" cam-ground tin-plated aluminum alloy piston with an autothermic strut. But that's just guesswork on my part, someone else may be able to positively identify the significance.

As in almost all the prewar engines 1939 and back, pistons were selectively hand-fitted and letters were used to identify under and oversize pistons; in 1937/38 A, A-A, B, B-B, C, C-C, D and D-D were used for this purpose but these were marked on the pistons themselves and not as a suffix to the engine #.

My 1937 Twelve engine is 905757A. So it's earlier than yours and still has the A suffix. My chassis is a fairly early 1937, probably actually built sometime in late 1936. So my thought is the early 1937 Twelves had the A suffix and then it changed to ???

Thanks to both of you for your replies. I guess I'll just have to wait and see what I find when I get into the engine...

So my thought is the early 1937 Twelves had the A suffix and then it changed to ???

I don't think that holds water. Here's a list of 1937 Twelve engine numbers known to me from my theft-proof data collection study. They are in order of lowest to highest theft-proof numbers - so more-or-less in the body build order. There are earlier engine numbers without the suffix. Though pretty slim amount of data to base conclusions on, no apparent correlation to chassis type either as both these "A" engines are 1507s, as are both earlier and later motor numbers without the "A". Both of the "A" numbers were on body type 1036 but so was 905539 if that means anything. It remains a mystery to me, at least for the moment. I've asked one of the major rebuilders of Twelves if he knows - and await a response.

905539
905820A
905953
906080A
906238
906274
906172
905702
905744
905719
906639
905774

Since it's a small percentage of engines that have a "A" in their serial number, perhaps it's more along the lines of over sized rod or main bearings. As these engines were hand built, when Packard encountered a crank that was "slightly off" and had to be ground another .010 from the norm to make it work, the "A" in the engine number would alert them if a dealer or rebuilder ordered replacement bearings down the road.

What you describe was notably practiced by Chrysler Corp., especially in the L-head 6-cylinder engines in the lesser makes like Plymouth, but I rather doubt Packard did it and I've never seen evidence of it. I certainly don't have a full list of engine suffixes and surely don't have the one in question, but I have quite a few and in every case except one (oversize valve guides in the 22nd series) they identify running changes; for example to cam-ground pistons, to autothermic piston struts, to larger oil pans, to cast camshafts, to an alternate clutch vendor, changes in the alloy of bearing metals, etc.

Ian, your question really got my curiosity up, I checked with two sources I thought had the best chance of finding something

1. Checked with the engine restoration shop that has probably rebuilt/serviced more Packard Twelves than anyone else. He had no documentation of the suffix, had never taken notice of one (though that doesn't mean one didn't pass thru his shop), and had never found under- or over-sized components in an otherwise unmolested Packard engine.

2. Checked with a major historian who has a massive collection of original Packard service information including most if not all the service letter and other service documents for the 36-39 era. He searched and found nothing related to an engine# suffix for a Twelve.

So I guess for now it remains a mystery.

Owen, thanks for all your help. You have obviously spent a bit of time on this question, and I appreciate it. I'm new to Packards and I'm very impressed with how helpful everybody I've talked to has been, (both on and off this forum.)

I was wondering, could the suffix have to do with the type of heads on the engine? From reading the service manuals I understand there were optional and high compression heads available. As I said, I'm new to Packards and don't know much about them yet, so maybe I'm completely up the creek with this one, but I thought I'd ask anyway and see what you guys think.

If my memory serves me right, I think there were aluminum and steel (?) heads available.