Can someone tell me the name of the alloy used for the XK120 cylinder heads?

Hello All,

I have seen the alloy named before, perhaps in the 1953 article describing the XK engine that (I think) William Heynes wrote. My Jaguar library is in storage hence the question. We have to TIG weld a crack in a cylinder head. Thank! Gary

DTD424, it is a general purpose aluminum casting alloy.
TIG weld with Argon shielding gas.
I would take a die grinder and thin grinding wheel and make the crack into a vee groove, so you can fill it with rod.
The two most commonly used aluminum filler rods for castings are 4043 and 5356. In general, 4043 (and Hobart Filler Metals’ new 4943 alloy filler) is more forgiving in terms of weld parameters (shrinkage, cracking, ductility, and flow), it gives better puddle control, and can be used with a wider variety of base alloys.


correct…DTD424 was cited as the material, in the Jaguar guide, by Bentley, page 46. I am NOT aware of a change made after the initial runs…but it could have been modified along the production run. Nick

Thank you gentlemen, precise information and well appreciated!

Might be important - did you mean to say “now aware”, or “not aware” - big difference…