Section : Carburettors

Carb sizes 

Posted By : Chris Gray, 08-Jan-2004, 05:18pm

I was just wondering what difference it makes whether you have HS2s or HS4s fitted.

The reason I ask is that although I've got a MK4 engine in my car (okay, so technically it's a Dolomite engine, but I'm reliably informed that they're the same, and MK4 is quicker to type ), I'm pretty certain that my carbs are HS4s (presumably off the 1500 engine that was originally in my car).

Just idle curiosity really . . .

Cheers,

Chris.

• Carb sizes 

  Posted By : Mark Stradling, 08-Jan-2004, 05:43pm

  The HS4 carbs used on the 1500 have a hole in them 1.5" wide.
  
  The HS2 carbs used on the 1300 have a hole only 1.25" wide.
  
  Bigger hole means more air can be sucked into the engine and so more power.
  
  From memory the visual way to tell them apart is: HS2's have quite elegant, tall & narrow dash pot covers. HS4's have much fatter looking ones, with the odd metal ridge here and there. HS2's also have a longer 'neck' - HS4's have hardly any.

  • Carb sizes 

    Posted By : Chris Gray, 08-Jan-2004, 06:02pm

    Cheers Mark.
    
    I'll have to have a look next time I'm home from uni to make sure, but from your description, I'd say my carbs are almost certainly HS4s.
    
    Chris.

    • Carb sizes 

      Posted By : Philip Wright, 08-Jan-2004, 06:41pm

      Just to give something for comparison, here's my car, fitted with HS4's
      
      Phil - '74 Spitty

       

      
      
      Carb sizes

       

      • Carb sizes 

        Posted By : Chris Gray, 08-Jan-2004, 08:57pm

        Cheers Phil.
        
        My car's got HS4s then.
        
        Plus, I have the 1500 style air-box. I didn't mention it before, because I wasn't sure that proved anything (so many bits on these cars seem to be interchangeable, after all ), but James tells me that air-box will only fit HS4s.
        
        Good to know there's still SOME 1500 under the bonnet of my car.
        
        Chris.
        
        '78 Mimosa Yellow Spitomite

        • Carb sizes 

          Posted By : Philip Wright, 09-Jan-2004, 10:37am

          I did recently see a partially rebuilt Spit 1500 engine on ebay recently, if you look, it may still be there. Only thing is I seem to remember it was on the isle of white.
          
          Phil

          • Carb sizes 

            Posted By : Chris Gray, 09-Jan-2004, 01:55pm

            I can see a 1500 engine block (not much use to me without the rest of the engine ), but nothing else (at least, not for a 1500).
            
            Shame, I could have got one of the guys going on the Isle of White trip to pick it up for me.
            
            Doesn't really matter - I've decided to leave well enough alone until I have quite a lot of both spare time and money.
            
            Chris.

  • Carb sizes 

    Posted By : James Carruthers, 08-Jan-2004, 06:06pm

    Elegant HS2s...
    
    The give away is the manifold - 1500 doesn't have the breather pipe going in to the top - instead its a T pipe with the 2 breathers going in to the carbs direct.
    
    Anyone who's seen Barry Blakeley in action knows HS2s don't always hold you back over HS4s...
    
    (yes this is the car is for sale... not quite so clean anymore... but almost as eat-your-food-off clean)
    
    
    
    James
    
    69 Signal Red Spit
    

     

    
    
    Carb sizes

     

    • Carb sizes 

      Posted By : Mark Stradling, 09-Jan-2004, 10:32am

      Probably just an age thing, but my 1300 (444th car built in '73, curse you non-moving tax-exemption) has HS2's with a rocker cover->t piece->carbs breather.