19 replies to this topic

[Brams96]

Pretty sure its an HS2 (standard 998cc '91 engine). I basically just smoothed out the inside of the elbow and took a bit off the leading edge where the elbow joins the carb body as that was the sharpest area. I also just took of the casting edges inside the carb body.

[Retro_10s]

Pretty sure its an HS2 (standard 998cc '91 engine)

It should be an HS4.

[Asphalt]

The SU carb is a landmark in automotive engineering.
Be careful before you imagine you can improve it.

If you JUST LOVE tinkering then tinker away but I suspect you'll get more from the inlet
and outlet in terms of "change" than you ever will from a stupidly well tried and tested carb
which is still at work (and still on sale).

Pretty much all HS4s dating from the 80's and later were realy bad casts... It would be stupid not to 'smoothen' them. HIFs seem to be far better, quality wise. As are brand new HSs from today's production - they are just superb quality

For the breathing part I agree; a good intake is worthless if the outlet is bad...

[Brams96]

Retro_10s - How do I tell which one i have? Also I have a spare carb from the same type of engine, can I use them both as a twin set up?

[Retro_10s]

Hi,... to run them as twins you'd need to get hold of some linkages (expensive) and a manifold,.. but they'd also have to be a pair, If you look at twins you'll notice both carbs are not the same as eachother, there is a Left hand side carb and a Right hand side carb. so you'll need the opposite of what you have.

To I.D. the carb you have there should be a small piece of tin held on by a screw somewhere on the outside of it - this will have a code,.. something like 'FZX xxxxx' if this is not present you'll have to measure the hole in mm and see what it is.

I'd be surprised if it's an HS2, my money is on HS4 - that's what most minis are still today.