Mark V (3.5L) carbs

I’ve been offered a set of MK5 carbs and need to know if they are the same for my 120. I haven’t seen them yet, but told everything moves freely (which my 120’s do not).


Hi Phil,
I don’t have my catalogue books in front of me, but at the very least the carbs on a a pushrod are on the opposite side to an XK engine, so the linkages, flexible spring shafts etc etc will be different.

Hi Phil.
No, not suitable, the Mark V carbs are the H3 or H4 model and smaller diameter and only 2 mounting holes, vs 4 holes on the H6 carbs used on XK120 engines.



Mark V carburetters (smaller throttle diameter H3 or H4) are totally different to XK120 the larger H6 carburetters - indeed the most obvious difference being the mounting arrangement, so Mark V carburetters with a two stud mounting simply will not mount onto an XK120 Inlet Manifold with a four-stud mounting… see pic of Mark IV and Mark V two-stud mounting, vertically oriented… compare with your XK120 H6 carburetters…

Thanks for the photos Roger, they will not sit well on the 120 manifold.


Hello Phil, in addition to not fitting, the capabilities of the carbs are too low. S.U. quote maximum capacity in B.H.P. as:
H3 - 55
H4 - 65
H6 - 85.
You would find H3 and H4 underpowered for the XK120 application.