PaulyG: Unless the carb has spindle wear casing an air leak there would be little to gain in replacing it, save your cash, or put it towards a pair of 40's.


For your information I include my 123 Ign timing curve.

The engine is nothing special just a carefully put together assortment of mostly second-hand bits and bobs accumulated over the years.
It pulls smoothly all the way to my cowardly rev limit of 7k with a sound track to die for.
I dont use the services of a rolling road instead I use a my own wide band lamda sensor with some basic data logging software. I dont know the output probably somewhere around 120bhp to 130bhp which in a 1979 four seater is plenty enough to put a smile on my old face.


0 to 500 rpm - 8° (helps with cranking and avoids kick-back)
1000 rpm - 16°
2000 rpm - 22°
3000 rpm - 28°
4000 rpm - 34°
5000 rpm - 36°
6000> rpm - 38°

Engine spec;
+90 thou (1690cc)
BCF 3 cam
Verier timing sprocket
Big valve head
10.2 to 1 compression ratio (1300 pistons)
Twin 40 IDF down draught carbs
Dry sump