Tue Jun 17 10:31:29 1997
- Message No. 1058
From: Pierre DEBRAS
Subject: Carb balancing ...
Hi Sture and all,
my preferred one: technical Q/A :-)
Synchronisation of carbs is very easy to understand. It simply consists in
adjusting each carb piston opening (AT has two carbs...)
The quantity of mixture air/fuel that comes in each cylinder is directly
driven its corresponding carb opening. For the best efficiency of the
engine, each cylinder should get the same quantity of mixture. In other
words, the position of the piston in each carb must allow the same
quantity of mixture in each cylinder.
As you may already have noticed, the AT has two carbs ... but only one gas
handle. In fact, the cable is connected directly to one carb, while
connected to the other by an adjustment screw. This allow to adjust the
opening height to 'balance' the carbs.
Balancing is very easy to accomplish, but requires a measurement device.
In the past, mercury column (one column for each carb) were used. Although
it was by far the most accurate measurement method, the mercury is toxic
(especially the mercury vapor) and hard to handle. Now, you may use clock
vacuum meter (one clock per carb) or electronic vacuum meter, which
performs a comparative measure.
Let's imagine you have mercury columns. Here is the procedure. Raise the
engine to its normal temperature. Remove the tank. Remove the screew on
the inlet pipes, between cylinder and carb. Connect each column to each
pipe. Start the engine. The mercury height in each column indicates the
depression in each pipe. Turn the famous, legendary sync screw to adjust
the mercury level in both column to the same level. And that's it !! Do
that at idle speed and at +/- 3000 rpm. You must have the same height at
both rpms. You will notice that a well balanced engine runs "smoother".
This was a summarized procedure. If there are enough people interested, I
can write a detailed article that could go into Micha's database (ok,
Micha ?).
Regards
Pierre
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dipper@normans.isd.uni-stuttgart.de