About 8 years ago I acquired a pair of 2" SUs all set up on a manifold for a Sprint. It came off a car that had been used for racing. I am about to put these on the car I am restoring, but while cleaning them up, I noticed that unlike the standard 1 3/4 " SU set up, the choke only appears to be set up for the rear carb. There is no connection to the front carb. These carbs appear to be quite different from the smaller, standard ones.
Left, rear carb showing choke set up
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Right, front carb with no choke
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I am assuming in its current set up it is going to be difficult / impossible to start from cold? Some advice / suggestions would be much appreciated. Anyone got a 2" SU set up using these carbs?
Geoff
Incidentally there were 3 gaskets between the rubber mount and the carb including this copper one with a serrated inner edge.
Probably a not-so-smart answer: shouldn't we be looking at the other side of the front carb for the choke mechanism?
Because the rear carb choke mechanism has this holes in the 'arm' I suspect that a connection linkage could be / should be placed.
The choke mechanism does work on both carbs via the connecting rod (same as HS6) but it has no throttle advance so your car will start fine but you have to keep it going with your right foot. Once it's set up correctly though it hardly needs to run at all before you push the choke back in and it'll go all by itself. Are you sure you have all the linkages etc ?
No, there is no linkage at all. In fact the actuating mechanism to richen the mixture is on the right side of both carbs. I did wonder if i could change it over from right to left on the front carb, but that would require some drilling a tapping threads and I would still be short of some bits.
I have since been told that the engine will start with just choke on rear two cylinders, but I suspect it would be rather rough and difficult to drive until warmed up!
I have a set of HS8s on my Sprint. I had some factory choke parts for one carb and I made a mirror image set
for the other carb. It works well. I made a piece of flat bar to mount the choke cable between the two carbs
and used a lever available from Burlens to connect the cable.
I used to have 2" SUs on JYD. I only used the one choke on the rear carb. There was a place that supplied twin choke cables but long gone from my memory.
Sprintless for the first time in 35+ years. ... Still Sprintless.
Engines, Gearboxes, Overdrives etc. rebuilt. PM me.
I have the ST specification for the 2 inch su's somewhere on my computer. PM me your email address and I will send them through. It might not solve your choke issue (although it might show the set up as a diagram) but it does have the needle etc set ups.
Ian
... Still Sprintless.