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

The parts book gives the part numbers for the standard, low, and high compression heads, but doesn't say what they're made of.

I know the heads on my car are aluminum, but the car is still in storage at the moment so I can't have a look to check the numbers. It would be nice if they turn out to be the H.C. versions...

The different CR heads are not identified by part numbers. The letters "HC" cast in letters about 5/8" high at the top of the head near the rear indicates that it's a high compression head. "LC" similarly indicates the low compression head (primarily but not exclusively used for export models). The standard heads had no markings. This information is right out of the shop manual.

When in doubt you can cc the heads to determine the CR; the standard head was 37.5-41.5 cc; 23-27 cc for the high (7.00) compression, and 44-48 cc for the low (6.03) compression.

The aluminum heads allowed better heat transfer which in turn allowed higher compression ratios; however the earlier cast iron heads were and are much sought after as replacements as the aluminum was, by today's standards, a rather primitive alloy and they have suffered from corrosion effects, etc. New aluminum heads in modern alloys are available from several sources, but be prepared for prices in the range of $2000 each or thereabouts.

Could the "A" suffix to the engine number identify a factory replacement engine or block using the original number with the suffix to denote it was not original to the chassis? It would have been stamped by the servicing dealer. Just a guess...

(o{}o)

Think ive read that somewhere about it being a Fact. Reb. Maybe TECH LETTERS.