Converting a 957cc or 1117cc Fiesta Mk2 to run a CVH Engine
The easiest engine conversion you can do to a small engine Mk2 Fiesta is to replace it with a larger displacement CVH engine. The 8v CVH was fitted to cars in the range in 1.3, 1.4 and 1.6 variants from the factory, so with a few parts it’s a straight swap. If you’re going to the trouble of putting in a larger engine then it’s probably worth opting for the 1.6 version to maximise the power upgrade for your efforts.
Carb Fed CVH Conversion Parts Check List
Essential Parts
- CVH Engine
- CVH inlet manifold and Carb
- Standard or aftermarket air filter
- CVH exhaust manifold and XR2 exhaust system
- XR2 alternator and under hung Alternator bracket
- CVH Coil and associated witing to distributor
- Mk2 Fiesta CVH Engine Mount
- XR2 coolant hoses
- XR2 Radiator
- Xr2 Exhaust and manifold
- Drivers side Tie Bar and mounting bracket
- XR2 Gearbox cradle or add 10mm spacers and longer bolts to the existing cradle
Optional but recommended parts
- 5 speed BC box with suitable ratios (XR2 or other CVH engine FWD Ford)
- 5 speed gearbox linkage to match your year of box (pre or post 1986)
- XR2 suspension
- XR2 driveshafts
- XR2 vented brake discs, pads, carriers and calipers
- XR2 rear anti-roll bar
- XR2 Shock absorbers and springs
- XR2 8mm fuel pick up line
- XR2 brake servo and master cylinder
The CVH engine
You can get a carburetor fed NA CVH engine from a few different vehicles, obviously the Mk2 XR2 and also the Mk3 Fiesta 1.6S, Mk3 escort etc.
Note: Sierra 1.8CVH
The 1.8cvh engine fitted to the Ford Sierra is generally thought to be not worth fitting, this is down to a head design that isn't designed to maximise power, and a lack of available tuning parts.
Brake servo and master cylinder
The 1/1.1 litre brake servo and master cylinder fouls the distributor of the CVH engine, there are ways round it such as modifying/changing the servo brackets or fitting a slim distributor with angled HT leads, but switching to the XR2 version is the ‘factory’ way to solve the problem.
Mk2 Fiesta CVH Engine Mount
Ideally you need a Mark 2 Fiesta CVH engine mount, note that it’s possible to use a Mk4 escort mount, however it will need some modification to fit.
Using the 5 speed gearbox and shafts
It is possible to keep the 4 speed box, but you will find it desperately needing a 5th gear, especially for motorway use. The XR2 has beefed up shafts but you can retain your base spec ones, even with a five speed box.
Wiring and electronics
You can either upgrade your whole wiring loom to an XR2 version which will get you a few extra useful features, or if you dont have one, just add three main wires to your existing low spec loom (applies to manual vehicles only).
Lucas distributor with a small black box on the top and 3 connections
You will need to replace the coil for a suitable version that matches your CVH engine, you will also need the wiring plug for the module on the distributor. The plug has three wires that will need connecting up as shown below, a green to green on the coil black to black on the coil and brown to earth, simple right?
If you can find a carb fed escort or fiesta with the same system, you can pinch the entire ignition wiring from it, everything from the block on top of the dizzy including the 3 wires, and the coil with its connectors. The all you will need to do is supply the coil with a live wire and a connect up a feed to the rev counter as shown on the instrument panel page.
Distributor Wiring
| Distributor Module | Coil | Other |
|---|---|---|
| Green Wire | Green Wire | |
| Black Wire | Black Wire | |
| Brown Wire | A suitable earth point |
Some people have found that the water temp wire doesnt reach to it's new position, but before you go about extending it, it can be untaped from the loom to give it more reach