E tirado do forum Zetec.com:
passo a citar -> «Early Zetec engines ( designed by Yamaha and originally called Zeta ), had duf cylinder-heads, with hydraulic tappets but no valve-guide sleeves, so valve-stems siezed and demanded special Motorcraft 5W30 oil ).
They were withdrawn from use for a while, and a single-cam upgraded Ford KA engine used until the revised ZETEC SE was ready. It is fitted with bucket-shims. These engines use connecting rods made by powder-metallurgy ( sintered powder ).
The engine blocks and bores are alloy, as are small VAG and Toyota engines.
The upgraded Ford KA engine is still in use in the KA developing a rough 69 bhp, and has a single chain-driven OHC, which is much noisier than the belt-driven twin-cam 16-V ZETEC SE SIGMA / DURATEC.»