In low-speed engines of the type (OHV) – it’s not terrible, but That certain engines such attacks led to destruction in the first p / shaft, valves and seats. When too much heat reduces the time gap to the magnitude of valve opening. Engine loses power increases razshod fuel. But far more dangerous decrease in valve clearance. After all, no wonder they call heat. In ohc engines, the clearance between the valve and lever must be at t +20 C – equal to 0.15 for t-2oC – the gap is reduced to 0.12mm, while for plus 40C increased to 0.17mm.
The increase in the gap with increasing t come at the expense of greater than steel coefficient of linear expansion of aluminum alloys that of the cylinder head. Case radically varies with the engine running. Exhaust valves in this heat so that it is not just ‘eat’ an increase in the gap for uniform heating of the engine, but also significantly reduce the gap. In normal control during engine gap almost disappears: the heat valve has only a 40-50C degrees, and it will not get into the saddle. This means that now the moment of his life were numbered, so as not to heat transfer from the valve to a relatively cold saddle. And also a slight additional increase of t valve may occur due to improper use of gasoline, too late ignition mixture.
I think that of all the foregoing it is clear that regulate the heat valve clearances must be very accurate. Terms of adjustments of the engine: the first condition: the engine must be cool. Temperature must be above 30C. If the valve is regulated then condition two applies: the probe should be broad in order to eliminate the error when adjusting the valve. Condition three: use a special tool with a long arm, as tightening the adjusting couples usually very tough. When properly adjusted valve clearance probe 0.15 shall extend from the connecting rocker-cam p / shaft with a noticeable effort, but not clamped at the same time. It is best to repeat several times. And finally – to make sure that the adjustment will be made correctly and without error, remove the bed with the p / shaft – in doing so you make sure that the cam p / shaft worn out (or not worn), as well as a rocker – the condition of the surface of the rocker, who comes into contact with cams camshaft. good luck to you!
