Aluminium or Mag case- how do you tell?
 

Hello,

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

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

Aluminium is not dark grey like magnesium.
Lyndon

Put a photo up will tell you

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

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.

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

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

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.

Ah, right. Brain failure

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