OBSCURE BUT IMPORTANT TAPPET MATTERS.

Waikato Times, Volume 104, Issue 17586, 15 December 1928, Page 24 (Supplement)

OBSCURE BUT IMPORTANT TAPPET MATTERS.

We have often made allusion to the

I question of tappet adjustment and the I vital necessity for the owner-driver keeping a watchful eye on this part of his engine, in order to avoid power losses and unsatisfactory performance. It connection with this it may be pointed out that although certain manufacturers do not lay great stress on the necessity for making tappet adjustments when the engine has become thoroughly warmed up, there are very good reasons why tappets should never be adjusted when the engine is cold. When tappet adjustment is made with a cold engine it is always necessary to set the tappet to a somewhat wider clearance, so as to compensate for the subsequent expansion of the metal when the engine becomes

heated. Even assuming that all the tappets were to expand to an identical extent the adjustment with the cold engine must needs be more or less a matter of guesswork; but if we recollect that there is a varying expansion, and that, for example, the tappets of number one cylinder will probably not expand under running conditions to the same extent as those of number, six cylinder, we at once see the additional need for making the adjustments only when the engine has warmed up thoroughly, since by so doing there is no question of making rough-and-ready allowances for the expansion which will occur when the power unit has been running for some time. Gold tappet adjustment is, at best, only rough-and-ready guesswork.