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tuning s.u. 1800

Seemed so to me too but it should be pretty close. Granted, I've a b20 but I ended up 18 flats below "flush."

As stated 2 turns (12 flats) is the standard place to start with unknown carbs on an engine (or freshly rebuilt carbs).

Find a decent guide to tuning the carbs to go by as it is easy for us who do it reflexively to forget a critical step or two.

Some observations:

Do not touch the carbs until everything else is perfect, timing, point dwell/gap, valve lash, etc... carbs are last.

The dashpot oil is not terribly picky. Browsing manufacturers once (auto, motorcycle and the SU factory) yielded everything from 10w fork oil to "engine oil" and everything in between. If you have worn dampers a heavier oil may help smooth out your acceleration.

Dampers must be equal or acceleration will suffer. use your finger to push up the pistons as fast as you can (engine off). They should both go up at about the same rate. Swapping dampers may help equalize if they are uneven. If they are terribly uneven you should replace the "fast" one or just get two new ones from Burlen or some other supplier. releasing the pistons should yield a fairly swift drop to the carb bridge with an audible "toink." If not, something is gummed up, bent or mis-aligned (jet not centralized).

A good flow balancer is helpful for syncronizing the carbs but not mandatory. Some swear by the hiss heard through a tube held near the carb throat, others by the piston height when the throttles are opened. I like a balancer.

It is more critical to have the throttles open at the same time when the accelerator is pressed. That adjustment is a pain (and LAST) but worth the extra effort. Loosen the interconnect between the carbs before attempting to adjust!

Sluice the carbs with cleaner, if they are at all visibly grimy, before removing the air-cleaners and the insides once the cleaners are off. Follow the instructions on the can. Run the car to full-hot before messing with the carb settings.

--
Mike!






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