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Hi all

My 61 MK2 3.8 had twin 2" SU and polished inlet upgrade. It also has a falcon exhaust system.

It is driving well but smells very "fumey". Timing is good so I am going to hook it up to a Gunsons gas analyser.

Anyone have any idea what readings for CO2 and or Hydo carbons would be acceptable. It seems that I have been tinkering for ages with fuel mixture now - so I will try and adopt some science.

Tim

Hi Tim
I initially set my engine up near the 'optimal' air fuel ratio with a CO reading of around 1%. However, it ran out of steam at about 3800 rpm. When I asked Ken Jenkins, he suggested a CO reading of 6-7% across the rev range (I have a 2.4L Mk2 with a pair of HS6 carbs and twin exhaust a la 240). This level of CO seemed a bit too rich to me, though Des Hammill and the SU manual both recommend similar values. I'm currently running around 5-5.5% CO and the engine performs very well; I did not notice any improvement at 6-6.5% CO. I have not gone down the rolling road route though.
Best wishes, David

David many thanks for the help on this