Hi all. A further update on the idle screw / jet situation on this car.
I had to replace the battery recently - which involved taking the carb and the carb to supercharger manifold off (they really buried the battery well on these), so I took the opportunity to take the carb apart again. I stripped it down and put it through the ultrasonic cleaner. On putting it back together, I noticed that the idle jets were different sizes - a 45 and a 55. Strange - because as far as I can see, the carb consists of two identical circuits.
Just to recap, when I first got this car it didn't idle too smoothly and adjusting the single idle screw didn't seem to make much difference. The idle oscillated at start up, and in general, the car idled, pulled off, cruised and generally ran better with with some choke even when fully warm. Couldn't find any vac leaks, electrics were fine, fuel delivery ok, so I focused on the carb. I got another idle adjust screw and fitted it late last year in place of the blanking cap that was installed where the 2nd idle screw should be. Installing and adjusting it didn't seem to make much difference.
So - as it was still generally 'better' during idle situations with the choke slightly open - I took that to mean that the idle circuit was running a bit lean. My plan was to try some larger idle jet sizes given modern fuel v. 80s 5 star.
The next phase was to get some pairs of jets - 50, 55, 60, 65 and 70. After making sure that the carb cleaning and rebuild hadn't improved things, I installed two 70 jets in place of the 45 and the 55. I thought it best to go straight for the largest ones to make any effect more obvious. I then had the potential to adjust from 0 up to 1.4mm (combined) of idle jet. So - it started up ok and ran after a bit of twiddling of the idle screws, but it had reverted back to the oscillating tickover (see previous posts). However - I've now found that if I screw both idle adjusters right in (but obviously not driving them hard into the end position), the car is happy under all conditions. It starts fine, doesn't oscillate to any real extent, doesn't stutter at cruising and has no flat spots. I'm pleased, but I'd like to understand why this setting seems to cure the issues.
Does the Beta VX have a similar Weber DCNVH carb fitted? If so - I wonder if it has one or two adjuster screws.
Thanks for any input,
Justin.
