Aluminium or Mag case- how do you tell?

[DavidSwedem]

Hello,

Can somebody tell me how to tell if a case is Alu or mag, engine number starts with 614
Thanks

[roblav]

Engine type number is a good method. Using serial number, Typically, the 3rd digit is model year. So 1974... mag case.

[Lyndon302]

Aluminium is not dark grey like magnesium.
Lyndon

[Dpmulvan]

Put a photo up will tell you

[68tposcherally]

Find a non important spot on the case, scrape some material off and light ,if it burns it’s a mag!

[djpateman]

Here is my history of the early 911 engine case revision history:
https://www.early911sregistry.org/forums/showthread.php?63809-911-engine-case-Revisions

The earliest aluminium cases (65-68) had the serial # facing the rear. Then the magnesium cases had the serial # facing to the right. Late in the Mg period there were a few Al cases with 7R but these were for the RSR, and a few RS; so very rare.

The later aluminium cases from 1973 on, no longer had 901 prefix casting part #'s (below the oil return tubes) and instead had 911 or 930 prefixes. It literally takes seconds to tell the cases apart.

[Walt Fricke]

DJ - don't you mean from '74 on? '74-77 were the mag case years for the street models, no?

[manbridge 74]

First street 911 mag case was 1969. Porsche won some type of award for the casting of it.

[djpateman]

Originally Posted by Walt Fricke

DJ - don't you mean from '74 on? '74-77 were the mag case years for the street models, no?

Heavens no, the first Mg cases were in production for the 1968 Model year, and probably during Dec 1967. I have actually laid my hands on one prototype Mg case that was built into a test engine for a 1969 911S type 901/10 before the original aluminium case engines ceased production. All 1969 production were Mg cases.

[Walt Fricke]

Ah, right. Brain failure

[jpnovak]

put a drop of vinegar in a discrete area. Magnesium will bubble. Aluminum will not.