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Running Ford engines on unleaded.
With leaded petrol now not generally on sale in Europe there are a lot of cars having to use LRP (lead replacement petrol). There are also a lot of cars out there that could run on unleaded, which are not. To run continuously on unleaded fuel the engine must have hardened exhaust valve seats. Running a car that has not got hardened seats on unleaded will cause engine damage.
All Ford vehicles built after July 1989 can use unleaded fuel without any adjustments.
Some earlier vehicles/engines have hardened exhaust valve seats fitted and so can use unleaded fuel continuously but may need adjustment to the ignition timing.
The following engines can run on unleaded fuel continuously (have hardened seats):
DOHC engines out of Sierra/Granada
Zetec engines out of Escort/Fiesta/Mondeo
Cosworth engines out of Sierra/Escort and 24v Granada
2.4 or 2.9 V6 engines out of Sierra/Granada
OHC, CVH, Valencia and 2.8/2.3 V6 engines need checking as some are suitable and some are not.
From January 1989 all OHC engines are suitable to run continuously on unleaded fuel and have the head stamped as below. Some earlier Sierra or Granada engines can continuously use unleaded and can be identified by letters stamped on the cylinder head by No. 4 spark plug.
1.6 litre engines would have M, MM or N, NN stamped on the head
1.8 litre engines would have S, SS
2.0 litre engines would have P, PP or R, RR
All OHC engines with hardened exhaust valve seats have a white ‘F’ painted on the cam belt cover. Don’t use this as a guarantee because the cover may have been swapped of another car.
All CVH engines built from January 1985 can continuously use unleaded fuel but are not code marked.
CVH engines built before January 1985 that can use unleaded fuel continuously have ‘LPG’ stamped on the boss of the cylinder head above No. 1 exhaust port.
Valencia (OHV) engines 1.0lt & 1.1lt built from February 1986 and 1.3lt engines built from October 1985 have hardened valve seats and are not marked. Some earlier 1.0lt & 1.1lt engines have hardened seats, these can be identified by the letters ‘VG’ or ‘CL’ stamped on the rear of the cylinder head.
Cologne V6 2.3/2.8lt engines all need checking to see if they have hardened valve seats. If they are suitable they are stamped in the centre of the cylinder head exhaust flange. 2.3lt engines will have ‘B’ or ‘F’ stamped on the head 2.8lt engines will have ‘D’ or ‘E’ stamped on them.
Ford engines not mentioned above such as the Kent/Crossflow engine or the Essex V6 were never fitted with hardened exhaust valve seats and could only run on unleaded if hardened valve seats are fitted by an engine builder. OHC engines fitted to Capri’s or Cortina’s were never fitted with hardened valve seats.
Ford use to say it was ok to run most engines on unleaded even if they were not fitted with hardened valve seats, as long as you filled up with leaded petrol every forth fill.
This is not the case with LRP Ford say LRP must be used continuously to avoid engine damage.
Lead Replacement Petrol (LRP) has the same octane rating as leaded petrol 97 RON but does not offer quite the same level of protection as leaded. So it may still be necessary on high performance or tuned engines to have hardened valve seats fitted or use a fuel additive.
The ignition timing needs to be retarded when using unleaded to avoid pinking which is very damaging to engines. I can not list all the timing settings here but most engine need retarding by 2-6 degrees. The 2.0lt OHC engine normally needs the ignition timing retarding by 4 degrees.
With leaded petrol now not generally on sale in Europe there are a lot of cars having to use LRP (lead replacement petrol). There are also a lot of cars out there that could run on unleaded, which are not. To run continuously on unleaded fuel the engine must have hardened exhaust valve seats. Running a car that has not got hardened seats on unleaded will cause engine damage.
All Ford vehicles built after July 1989 can use unleaded fuel without any adjustments.
Some earlier vehicles/engines have hardened exhaust valve seats fitted and so can use unleaded fuel continuously but may need adjustment to the ignition timing.
The following engines can run on unleaded fuel continuously (have hardened seats):
DOHC engines out of Sierra/Granada
Zetec engines out of Escort/Fiesta/Mondeo
Cosworth engines out of Sierra/Escort and 24v Granada
2.4 or 2.9 V6 engines out of Sierra/Granada
OHC, CVH, Valencia and 2.8/2.3 V6 engines need checking as some are suitable and some are not.
From January 1989 all OHC engines are suitable to run continuously on unleaded fuel and have the head stamped as below. Some earlier Sierra or Granada engines can continuously use unleaded and can be identified by letters stamped on the cylinder head by No. 4 spark plug.
1.6 litre engines would have M, MM or N, NN stamped on the head
1.8 litre engines would have S, SS
2.0 litre engines would have P, PP or R, RR
All OHC engines with hardened exhaust valve seats have a white ‘F’ painted on the cam belt cover. Don’t use this as a guarantee because the cover may have been swapped of another car.
All CVH engines built from January 1985 can continuously use unleaded fuel but are not code marked.
CVH engines built before January 1985 that can use unleaded fuel continuously have ‘LPG’ stamped on the boss of the cylinder head above No. 1 exhaust port.
Valencia (OHV) engines 1.0lt & 1.1lt built from February 1986 and 1.3lt engines built from October 1985 have hardened valve seats and are not marked. Some earlier 1.0lt & 1.1lt engines have hardened seats, these can be identified by the letters ‘VG’ or ‘CL’ stamped on the rear of the cylinder head.
Cologne V6 2.3/2.8lt engines all need checking to see if they have hardened valve seats. If they are suitable they are stamped in the centre of the cylinder head exhaust flange. 2.3lt engines will have ‘B’ or ‘F’ stamped on the head 2.8lt engines will have ‘D’ or ‘E’ stamped on them.
Ford engines not mentioned above such as the Kent/Crossflow engine or the Essex V6 were never fitted with hardened exhaust valve seats and could only run on unleaded if hardened valve seats are fitted by an engine builder. OHC engines fitted to Capri’s or Cortina’s were never fitted with hardened valve seats.
Ford use to say it was ok to run most engines on unleaded even if they were not fitted with hardened valve seats, as long as you filled up with leaded petrol every forth fill.
This is not the case with LRP Ford say LRP must be used continuously to avoid engine damage.
Lead Replacement Petrol (LRP) has the same octane rating as leaded petrol 97 RON but does not offer quite the same level of protection as leaded. So it may still be necessary on high performance or tuned engines to have hardened valve seats fitted or use a fuel additive.
The ignition timing needs to be retarded when using unleaded to avoid pinking which is very damaging to engines. I can not list all the timing settings here but most engine need retarding by 2-6 degrees. The 2.0lt OHC engine normally needs the ignition timing retarding by 4 degrees.
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