Escort Engine CVH

CVH

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Compound Valve-angle, Hemispherical combustion chamber

The CVH engine was introduced with the new mk3 Escort in 1980 and saw service through to the early mk5 Escort. It was also fitted to the Equivalent Orion's and the Fiesta from mk2 guise A redeveloped version also found it's way into the Sierra. Initially it was available in three capacities, 1.1ltr, 1.3ltr & 1.6ltr. Later 1.4ltr and 1.8ltr versions joined the line up but these differed a bit from the original engines as will be explained.

The Engine
The engine is of single over head cam, eight valve design and consists of a conventional iron block with a five main bearing crank (some older small engines such as the OHV engine only used three main bearing crank) and an alloy cylinder head.The cam shaft is driven by a conventional toothed belt which also drives the water pump and the cam shaft operates the valves via hydraulic followers (with one exception, the RS 1600i uses shimmed solid followers) and rockers.

All engines were designed to run on leaded petrol up until October 1985 when Ford fitted hardened valve seats to the cylinder heads to allow the engines to run on unleaded. This of course is right at the end of the mk3 Escorts production run so the majority of the mk3 Escorts out there will have left the factory with leaded petrol heads fitted. All mk4 Escorts however should be safe for unleaded petrol.
In 1986 a lean burn version of the engine was introduced which featured a modified cylinder head chamber. Instead of being of hemispherical design it used a heart shaped combustion chamber. The idea behind it was that it would push the combustible mixture towards the spark plug. To account for the reduced capacity caused by the intrusion into the cylinder head chamber to create the heart shape, the pistons were modified to bring capacity back up to the correct amount. This of course means that if you were to fit a standard hemi head to a lean burn bottom end you'd end up with a slight increase in capacity but a lower compression ratio and vice versa if you fitted a lean burn head to a standard bottom end. The 1.4 ltr version replaced the 1.3ltr engine in this year too.
As previously mentioned, the Sierra also used the CVH engine and came in both 1.6ltr and 1.8ltr sizes. However, don't get excited about plans to fit a 1.8ltr CVH from a Sierra into your Escort. The engines are very different from the CVH we are used to. They underwent many changes to be made suitable for the rear wheel drive application including new mount locations on the blocks and repositioning of the distributor etc.. They didn't have fantastic performance and have been all but ignored by the aftermarket tuning industry so there's not much that can be done to improve them. If you want bigger capacity beyond the existing transverse CVH range then you need to look for an alternative engine.

Induction - Carburettors
Most of the engines in the mk3 Escort were Carburettor fed with Bosch mechanical fuel injection being fitted to some of the top spec models. Two types of carburettor were used, Fords own variable venturi (VV) carburettor and a Weber dual venturi (2V) 32/34 DFT carburettor. The fitments were as follows:
Ford VV Carburettor
1.1ltr..........81SF-9510-KAA
1.3ltr..........81SF-9510-KCA
1.6ltr..........81SF-9510-KFA
Weber 2V 32/34 DFT Carburettor
1.6ltr (certain models only).....81SF-9510-AA
If you wish to fit the Weber 2V carburettor in place of a Ford VV on your engine then you'll also need the corresponding inlet manifold as the base flange is different. As far as I am aware the mechanical fuel pump is common to all carburettor fed engines.
Later engines including engines fitted to the Fiesta range used different variations of Weber DFTM and TDL carburettors.

Induction - Mechanical Injection

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The first production fuel injected CVH engines used the try'd and tested Bosch K-jetronic mechanical fuel injection (MFi) system. This is a continuous injection system using an airflow sensing plate mounted on a pivot to meter the rate of fuel flowing through to the injectors. Although fairly agricultural in operation it has proven to be a highly reliable system and can be found fitted to a multitude of different manufacturers cars including Ferrari! I have created a simple idiots guide as to how this system works that can be accessed further down this page.

There were two more fuel injection systems fitted to the CVH throughout it's life, Central Fuel Injection (CFi) and Electronic Fuel Injection (EFi) covered shortly. Both are electronic systems with many similarities in the way that they operate. However, the CFi system uses a single fuel injector mounted in what looks very much like a modified carburettor mounted on a conventional inlet manifold. I haven't covered the CFi system in any detail on this site as it was never fitted to any production mk3 or 4 Escort and retro fitting this system to any car would be a ludicrous waste of time and money.

Induction - Forced Induction
In 1984 Ford released the Escort RS Turbo. This as you probably already know and as the name suggests featured a turbo charged version of the CVH engine.It utilises a Garret T3 turbocharger and a modified version of the Bosch injection system designated KE-Jetronic which features additional electronic control.

Induction - EFI - Electronic Fuel Injection

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The last year of mk4 Escort XR3i production saw the adoption of the EEC IV engine management system. Despite being named as EEC IV, it was actually the first production version, the previous three versions being development models. It was a bit rudimentary compared to todays systems with a separate ignition module but it still achieves the same end result. With after market remapping it has the capacity to be more tuneable than the Bosch K-jet system it replaced to get the best out of any engine modifications. Retro-fitment to a mk3 is possible but even if you do manage to find a donor car you will require so much from it (including fuel tank that requires its own mods) that for the end result it is a mammoth task that is just not worth it. You won't gain any extra power and it was criticised in its day for suffering flat spots. For the effort, just fit a Zetec.

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Bosch K-Jetronic MFi

A simplified 'idiots' guide to the workings of the popular mechanical injection system.

MFi Crankcase Breather System

The crankcase breather system suffered from clogging issues and so saw a number of revisions. This section gives details of the best combination of parts.

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The contents of this website are purely a reflection of my own experiences and knowledge gained whilst working on my various projects. Anything you do based on what you have read here is done so entirely at your own risk.
Personally I wouldn't trust someone like me with a lawn mower! You have been warned! Flapper-bat!

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