Join Date: May 2015
Location: Shoreham-by-sea, West Sussex, UK
I was quite surprised that the previous owner had just carried across the carbs without changing the jets or venturis. I figured that updating the carbs with 32mm venturis and 135 mains would ensure that the power was about right and more importantly that the mixture at full throttle would be safe (i.e. correct degree of richness). 34mm venturis is also an option.
Also, changing the idle jets would mean I get the correct mixture at part load for good driveability and fuel consumption.
I have had some trouble with the engine stumbling at around 2000rpm - when I got it but also after the updates. Running richer jets helps - 55F8 or 50F9, but perhaps that means my carbs need a good clean. More tinkering required.
1975 GT Junior with 2 litre lump
2006 Subaru Impreza WRX