Folks, recently some one sent me a question regarding the switch from SU to ZS
carbs for TR4's and TR4A's. Thought some of you might be interested.
QUESTION:
> I would be interested to know why Triumph switched [from SU's to ZS's]....
ANSWER:
Simple answer actually. SU's were built by a rival (British Motor Corp. -same
outfit that made MG autos). Triumph was paying more than they felt was
necessary. So they contracted with Zenith Stromberg to build a carburettor
which worked on the same principle (Constant Pressure Differential -CD) The
intake manifold was not even changed, so either carb can be used with mods
only to the carb control linkages. TR4's had SU's from CT1E (remember E is an
engine number) to CT 16800E, then a trial run of ZS's from CT 16801E to CT
16900E. From CT16901E to CT 21470E they went back to SU's. I think it was
for 2 reasons: a) They were negotiating with Zenith Stromberg on price etc.
and b) they still had some SU's on hand. Triumph then changed over to ZS's
from CT 21471E until the end of the TR4 and continued well into the TR4A's.
Cheers.
Art Kelly
|