early aluminum case vs 7r mag case weight

[gestalt1]

hi all, i just for fun weighed a 1975 7r mag case and it came to 38.7 lbs. the sandcast aluminum case weighed 53.98 lbs. the difference is 15.28 lbs, not the 22 lbs often quoted. just though this would be of help.

[Shoepop]

Need to consider them with the cam towers, chain box/cover's etc.

[Flieger]

7R case has the most reinforcement ribbing on the inside, as well.

[gestalt1]

i think on a mag case engine the only parts that are mag are the case, the chain boxes/covers and the valve covers. i guess the weight savings of those parts plus the 7r ribs could make for the 22lbs. when others have asked what weight savings they get by going to a mag case it is not 22lbs unless those other parts are changed as well (not sure who would use mag lower valve covers!).
i'll stop weighing stuff now.

[Flieger]

I found the weight interesting. Thanks for your effort.

[stownsen914]

Years ago I weighed my 3R mag case and the sand cast aluminum one that was replacing it. I don't recall the exact weights, but the difference was 18 pounds.

Scott

[Flieger]

So the 7R reinforcement ribbing is more extensive than it first appears. Interesting.

Even though the 7R is not as much lighter as first thought, the metal mass is less dense and spreading the volume out in those ribs should provide a stiffer Magnesium case than the Aluminum sand-cast version. (Assuming equal temperature effects.) The Magnesium case can either be lighter than Aluminum for the same stiffness (but possibly weaker ultimate yield and fatigue strength) or it can be stiffer for the same weight.

[Peterfrans]

I just weighed some cases I have:
a very late 7R with steel headstuds weighes 19.5kg (43lbs)
a 3R withoud headstud weighes 16kg (35lbs)
a 67 alu case without headstuds, bored for a 2.7 weighes 22kg (48lbs)

Although not done with the most accurate scale, it is surprisingly close in this case. I would have thought that the alu case would have been much heavier

I have another 7R case (73.5) which I will also put on this scale to see where this one is at.

[Peterfrans]

my second 7R case (with headstuds) from a 2.4 weighs in at 20kg (44lbs)

[safe]

Isn't the quoted 22lbs the difference going from a mag 7R case to the alu 930 case?

[Flieger]

No, from early Aluminum to Magnesium case for 1969 model year (August 1968 to July 1969) according to Fere, Ludvigson,...