IDLE THOUGHTS
QTry as I might, I can’t get my 903cc Fiat Uno to idle nicely. It randomly ‘misses’ whatever I do with the idle screw. Any tips?
Gavin Endacott, Ruislip
Ed says:
AFirst check the ignition timing.
The points should be just opening as the crank pulley passes the 5ºBTDC mark. As the engine is a chain-driven OHV type, the cam timing is unlikely to have been interfered with, so check this last. OHC engines, and engines with timing belts, are often wrong. Use the manual to verify the sprocket timing marks on the crankshaft and camshaft line up at the same time (once every two engine revolutions).
A variety of carburettors were fitted, so consult your manual and make sure the float level is correctly-set. Check for vacuum leaks and make sure the vacuum advance pipe for the distributor is fitted on the correct stub on the carburettor. Make sure all mating surfaces of the carburettor are flat and that the gaskets are in good condition. Then check the valve clearances with the engine stone cold. These should be 0.15mm for the inlet valves and 0.20mm for the exhaust valves.