Section : Carburettors

SU Conversion

Posted By : David Hudson, 10-Feb-2003, 10:53am

I'm thinking about converting my MkII Vitesse from Stromberg to SU carbs. I know this is a fairly common mod, and I would be interested to know what size SUs have been used, and whether the benefits have been worth it.

I also remember someone converting to triple SUs in an old issue of the Courier. Anyone got any experience of this?

Followups :

SU Conversion

Posted By : Graham Reeks, 10-Feb-2003, 03:42pm

I've just received some SU HS4 carb's with manifold from a 2.5 saloon, and am thinking about bolting them on my GT6. Not entirely sure why ... perhaps just for the hell of it, and because the CD150s have never been particularly good. Any info. would be appreciated (even arguments for not doing it!)
- SU Conversion
  
  Posted By : Graham Bingham, 10-Feb-2003, 07:17pm
  
  Blimey, thats worried me a bit, whats wrong with Strombos? My 67 2Lt Vit seems to run OK on them. What are the advantages of SUs? My old Dolly Sprint had SUs and I seem to remember constantly stripping and cleaning and filling with oil or was that my Mrs?
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    Posted By : David Hudson, 11-Feb-2003, 10:47am
    
    I'm not exactly sure what benefit SUs will give either. The only problem with the Stromberg CD150s in my car is that the engine is very lumpy at tickover (always has been since the day it was new) and the idle speed has to be set quite high - approx 900 RPM. I put this down to the carbs because I once saw a 2LMkII engine with twin SUs that idled very smoothly at a much lower RPM. Once the engine is up above 1500 RPM it is beautifully sweet, so there is no problem with the driving experience.
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      Posted By : David Rumens, 07-Mar-2003, 09:45pm
      
      The conversion to HS6 SU's 1.75 in is worth considering if you use the shorter type from the Dolly Sprint. Use BAE needles and Green Springs.
      
      Cheers,
      
      Dave
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  Posted By : Nathan Gabbott, 11-Feb-2003, 09:00am
  
  One thing to note if you are using a saloon manifold, is that the saloon engines were canted over a bit, this means that fitted to a vetical GT6 engine the carbs will
  
  a) probably interfere with the bonnet
  b) not sit level, so the float chambers will either flood the carb, or supply no fuel.
  
  I have heard of some people cutting a slice from the manifold and welding it back up, but this seems to be a alot of trouble to go to!
  
  Nathan
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    Posted By : Nathan Gabbott, 11-Feb-2003, 09:02am
    
    I'm a dunderhead, just noticed it's a Vitesse, so more likely to clear bonnet, will still suffer from float problems though.
    
    Nathan
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      Posted By : Graham Reeks, 11-Feb-2003, 10:51am
      
      ... but mine's a GT6! Thanks for the advice, the SUs can wait a while in that case, it's more important I rewire first.
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        Posted By : John Davies, 11-Feb-2003, 11:55pm
        
        All,
        A 2.5 manifold with HS6s will JUST fit under a Vitesse bonnet, if that is adjusted upwards as far as it will go. You still risk rubbing the front damper screw on the bonnet.
        
        The HS6 float chamber is bolted to the body - it is possible to fettle the joint so that it sits vertical and bolt it up again. The angle is less than 10 degrees - the carbs will probably work well without this though.
        John