Gareth, look at the bottom of the jet tube on each carb; if it is straight all the way down then you have non waxstat. If however there is a flatish circular metal fitting at the very bottom of the tube, about the size of a one pence piece then you have waxstat type.
The circular metal thingy contains a wax capsule, when the engine bay is hot this capsule expands & pushes up on the needle, which effectively weakens the mixture slightly. AFAIK waxstat was only fitted on late cars & was probably related to emissions and/or fuel economy reasons, however many people report poor hot idle & issues with accurate tuning on waxstat carbs.
You can change from waxstat to non waxstat jets but beware that parts of the choke linkage must be changed as well - complete kits are available. I have also heard that rather than go to the expense of a conversion, some people carefully open the metal fitting, remove the wax capsule & replace it with a penny, then reassemble. The penny keeps everything in the right place but of course will not expand to anything like the degree that the wax capsule does, so effectively makes the carbs non waxstat.
Tony
<font size="1">1981 TR7 FHC Cavalry Blue
1980 TR7V8 DHC Jaguar Regency Red - sadly sold!
1977 TR8 FHC EFI Factory development car Inca Yellow</font id="size1">
