Twin carbs for 13/60

[chrisg]

Tomorrow, I'm Going to replace the clutch plus finish up some bits on the braking system of my car. At my local mechanic's garage there is a set of twin su's with manifold from a spitfire. My mechanic said that they can easily fit on the 13/60.. now my question is, except from more fuel consumption, is there any real difference in power?, I did some research myself and as i suspected(owned an alfa 33 twin carbs) you can only benefit from them at very high revs. is this correct?

[Clive]

Can of worms here.....
The herald engine is different from a spit 1300. It has a "softer" camshaft, plus lower compression.
Will you see a difference in power?? I doubt it, maybe a tiny bit, but probably not worth the hassle. If the carbs are from a later spitfire (1500) they are HS4's, which will make your car worse unless you do some other engine modifications. So in all, I would keep it as is :)

But of course, it may be worth nabbing the carbs if they are cheap enough, just in case you get all into modifying he car later.

[ferny]

I did notice a slight increase in torque.

[MarkB]

I have tried a pair of HS4's on a standard Mk3 engine and thought it was a backwood step when compared to the HS2 setup. On a standard engine the air speed is going to be slower with the bigger carbs and in my case I felt that I lost some low down torque. Hotter cam, higher compression and bigger valve's, HS4's are probably the way to go. On a standard herald engine I would stick with the original single carb.

Mark