1966 Spitfire Mk2 Sports Exhaust & Carb Settings?

[KevinB]

Hi,

So my next naive question is about the carburetor settings when you have a sports exhaust fitted to a  Mk2 1966 Spitfire? My new restored Spitfire has a brand new stainless steel twin sports exhaust fitted.  

Now we're trying to tune the engine to get it to run a bit smoother, I noticed, by accident, in the Rimmers Parts book for the Spitfire that it says that if you have a sports exhaust fitted to will need to tune the carburetor accordingly and possibly fit new needles. I was wondering if anyone had fitted a sports exhaust and then made any carb adjustments? 

Any advice most welcome

Cheers, Kevin    

[johny]

What exactly are the symptoms? Before adjusting your mixture adjustment you need to make sure everything else is correct (compression, no air leaks, valves clearances, correct plugs and gap, timing, carb balance, carb damper oil, float heights etc).

[Pete Lewis]

 to add,  unless you have a 4-2-1- tubular  manifold and silly pancake air filters there is little change just fitting a slightly more free flowing exhaust has little effect on settings 

Pete

[Adrian Cooper]

The Mk2 should have a 4-2-1 manifold as standard and if you still have this there is, as Pete says, no real difference between the standard set up and the twin. I would suggest keeping the needles you have and working through Johny's excellent list.

Adrian

[NonMember]

As Pete and Adrian said, the change of needles is for people (like me) fitting 4-2-1 tubular systems to cars that originally had cast manifolds. Since the Mk2 already had a 4-2-1 tubular manifold, you shouldn't need to fiddle.

[Nigel Clark]

Make certain the engine is in good health, checking valve clearances, points gap and ignition timing (preferably with a strobe).

Take the float chamber tops off and check the float height settings and condition of the needle valves.

After that, you're ready to tune the carbs. Just fitting a sports exhaust shouldn't need a change of needles. Adjust the carbs as per the methods in the workshop manual or Haynes book and all should be well.

Nigel