The carbs themselves are interchangeable, as they just bolt through an adapter plate - the hole spacing is the same across all SUs.
If you do put the HIF6 (2200 carb) on the 2000, you would need to swap the needles over as the HIF6 will have a slightly richer needle to make use of the 2200's additional displacement.
After that it's really
a question taste:
The HS6 is a far simpler carb that is very straightforward to maintain, and the choke/fast idle arrangement has fairly infinite adjustment to get the settings just right. However, it has its drawbacks such as slight fuel flooding/starvation under heavy braking/acceleration; and zero sensitivity to changes in fuel temperature.
The HIF6 is a far more intelligently designed bit of kit. The float is integrated into the body to combat the issues above, the jet is mouted in a bimetallic bracket that warps depending on temperature to move the jet up and down fractionally. It also has an overrun duct so that fuel dribbles straight back down into the float chamber on overrun, and it has a separate choke jet on the far side of the butterfly to seriously aid cold-starting!
The downsides are that it is VERY difficult (but not impossible) to change the float in situ, the seals have to be A1 to prevent leaking, and the float/inspection cover is on the underside of the carb against the heat shield.
I'd be interested to see how a 2000 would perform through a single 2" HS8 but I wouldn't recommend it for daily use! I'm sure it wouldn't make that much difference generally, as I don't think the extra throttle area would sufficiently compensate for the manifold design at higher speeds.
It's worth experimenting to find what works for you. Rover 2000 HS6's are on ebay regularly for about £10-15 so you could always get one and transplant the good parts from your knackered one.
Michael
