v12 stromberg jet size

[Chrispy]

hi guys curious, I have a X use v12 with stromburg175 cd 2 carbs. the emissions has been removed and runs very rich to the point of backfire. it is leaned off to the max. so my question is are the European jet sizes different to USA polution sizes.

[Bob.]

AFAIK there was only one jet size but various needles depending on year, market emissions requirement, car model. Check with Burlens who make them - https://zenithcarb.co.uk/.
Search this forum and on https://forums.jag-lovers.com, there have been plenty of discussions about setting these carbs up.

[MarekH]

Have you considered that the brass jets may be worn after 50 years and so may now be a wider hole? This would make it run rich as would a worn needle.

Measure them. The needles are all published sizes in the Stromberg manual and the the jet diameter will also be published somewhere.

kind regards
Marek