The CVH Engine

Introduction

The CVH (Compound Valve angle Hemispherical combustion chamber) engine was originally introduced in 1980 for the Escort after a six year genesis period. It was unique because the valves are mounted at a compound angle, which allows for a hemispherical combustion chamber shape without using a more expensive twin camshaft arrangement. It was also the first European Ford engine to use hydraulic valve lifters.

Most derivatives were replaced in 1992 by the Zetec, but the 1994 mark three Fiesta 1·4 Si and a number of Escorts used a variant on the 1·4 CVH engine called the CVH-PTE (frequently known as the 1·4 PTE), which features a number of refinements. When the Focus replaced the Escort, the CVH was finally pensioned off after nearly twenty years of service.

Variants

Throughout its production life, the CVH had a reputation for being harsh and noisy at high speeds, and for lubricating the oil to sludge prematurely. Whilst later revisions to the engine, particularly the PTE derivative, smoothed and quietened the unit down, I cannot over emphasise the importance of regular oil changes.

The 1·3 used in early mark two Fiestas offered respectable performance because of sensibly low gearing, low weight and decent engine output (69 bhp).

The naturally aspirated 1·4 and 1·6 were used in the Fiesta and Escort. Neither are especially refined nor economical, but of the two the 1·6 is the one to have. The 1·4 was introduced with some fanfare as Ford’s “lean burn” engine, because Ford switched from a mechanical operation of the second venturi to a vacuum operated system. Unfortunately, this had a habit of letting the engine run horribly lean rather than supply the correct amount of fuel. Bits and pieces from the 1·4 are not compatible with any other CVH engine. In 1995, the 1·4 was modified to produce the CVH-PTE, which incorporates a number of simplistic changes designed to smooth and quieten the engine.

The 1·8 was only used in the Sierra. Despite offering broadly the same amount of power as the later carb-fed 1·6, it does provide for more torque and is usefully smoother (especially the later engines produced in the early 1990s). However, there are some important differences between the 1·3, 1·4 and 1·6 to the 1·8 and the two families are not directly compatible.

There is also the 1·9 CVH, which to the best of my knowledge was only sold in North America. It is possible to convert a 1·6 into a 1·9 and some companies, such as Specialised Engines offer the conversion or swap service.

Mechanical Reliability

The standard “atmo” CVH engine is basically a tough engine but it does suffer from some problems, mainly valve stem failure (causing excessive oil burning) and its ability to convert oil into sludge.

In turbocharged guises, the headgasket can be a weakness, more so if the boost pressure has been uprated.

Like all engines, regular oil and filter changes should be considered an essential part of maintenance.

Tuning

The CVH is considered to be one of Ford’s easiest engines for tuning purposes and a huge variety of uprated parts are available, from camshafts to heads, to low compression pistons for turbocharging.