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20R, 21R, 22R engines

A lot of this data was collated from discussions on the Classic-Celica group.
The common settings were copied from the Haynes "Celica 1971 thru 1985 RWD" manual - 92015 (935)
and from the Toyota Manual "21R, 22R Engines - Repair Manual" Pub No.36056E;.

Engine	Comment
20R	2200cc with carburetor
21R-U	2000cc with carburetor and Japanese pollution control
21R-C	2000cc with carburetor and international pollution control
22R	2400cc with carburetor
22R-E	2400cc with EFI
22R-EC	2400cc with EFI with even more pollution control
22R-EU	2400cc with EFI and Japanese pollution control
22R-TE	2400cc with EFI and turbo (low compression, low boost for low HP but high torque for small trucks)

These engines are essentially identical apart from the width of the pistons.
All major parts will interchange except the pistons and the block.

These engines are an overhead cam, overhead valve design with 4 inline cylinders.
The block is cast iron and the cylinder head is alloy.
There are no twincam versions and twincam heads from other engines do not fit.
All versions can use unleaded fuel because all alloy heads have hardened valve seats.
Some external parts are interchangeable with other R series engines.
Most cars with any R series engine can accept these engines (beware of extra height).

Most of these engines use a single Toyota downdraft carburetor.
The 22R-E/EC/EU/TE had EFI.

There were 2 versions of the 22R - the early tall deck and the later short deck.
The short deck has a slightly lower block than the tall deck.
The short deck uses a 2 less links in the timing chain.
I have been told that the 96 link single row chain can be upgraded to a double row by using a modified early 22R timing cover, oil pump, drive spline.

Engine	Years	cc	Bore	Stroke	Block height	Piston type	combustion chamber type	Timing chain		Air injection	Exhaust O2 sensor
20R	75-80	2189	88.5	89.0mm	tall	?	?	98	double	98	no
21R		1972	84.0	89.0mm	tall	?	?	98	double	?	?
22R	81-82	2366	92.0	89.0mm	tall	?	?	98	double	no	?
22R	83-84	2366	92.0	89.0mm	tall	dome	open	98	single	no	?
22R	85-	2366	92.0	89.0mm	short	flat	small	96	single	no	?

The 20R exhaust manifold had air injection that mounted on the manifold top and no oxygen sensor mount.
The 22R does not and some do and dont have an oxygen sensor mount.
The 20R exhuast manifold outlet has a single outlet into the exhuast pipe.
The 22R exhaust manifold had dual outlet.
The 20R exhaust manifold usually had 1 lower center mount stud.
The 22R exhaust manifold usually had 2 lower center mount studs.
Some early 22R exhaust manifolds had single lower center stud hole.
Some 22R exhaust manifolds had both configs of holes and had 3 holes.
Aftermarket exhuast manifolds usually fit all 20R/21R/22R by having all possible holes.

Depending on the country and year, some engines had points and some had electronic ignition.
You can upgrade to electronic ignition by using the distributor internals from any R or T series engine with EI.
You also need the corresponding ignitor module.
Note: early model EI has an external ignitor bolted to the coil and later model EI has the ignitor inside the distributor.
Both types can be used on any R or T series engine.

The 21R engine wasn't sold new in America but is easy to find at engine importers.
In most cases you will need to swap the oil pan for a 20R or 22R oil pan so that the sump clears the crossmember.
The 20R was only sold in America - most other countries used the 18R until 1981.
In Australia the 21R-C replaced the 18R-C in 1981 and was replaced by the S series engines in 1983.
In Australia the 22R-E was used in top end Celicas and Coronas for mid 1984 to mid 1985 only (short deck).

There are many variations of pollution control on these engines.
These include various PCV's, air injection pumps, recirculating exhaust gases and different cams.

The 20R head has smaller combustion chambers than the 22R.
Using a 20R head on a 22R tall deck block will raise the compression ration.
This will allow you to tune the engine to give greater power.
The 22R block will fit anywhere a 20R block used to be, so this is a recommended upgrade for both 20R and 22R owners.
I suspect that a 21R on a 22R tall deck block will also raise the compression.

LC Engineering specialise in the 20R/22R and have many performance parts for them.

Common settings
Bore x Stroke 20R	88.5x89mm
Bore x Stroke 21R	84.0x89mm
Bore x Stroke 22R	92.0x89mm
Inlet valve clearance - hot	0.20mm (0.008")
Exhaust valve clearance - hot	0.30mm (0.012")
Timing 21R-C(Australia) manual	5° BTDC at 600rpm
Timing 21R-C(Australia) auto	5° BTDC at 650rpm
Timing 21R, 21R-C(Sweden)	8° BTDC at 750rpm
Timing 22R	8° BTDC at 950rpm
Firing order	1-3-4-2
Idle speed - manual	800 ± 50 rpm
Idle speed - auto	850 ± 50 rpm
Fast idle speed 21R, 21R-C	2400 rpm
Fast idle speed 22R	2600 rpm
Fast idle speed	2600 ± 200 rpm
Compression 21R - standard	11.0kg/cm² (157psi)
Compression 21R-C - standard	11.5kg/cm² (164psi)
Compression 22R - standard	12.0kg/cm² (171psi)
Compression 21R, 21R-C - minimum	9.0kg/cm² (128psi)
Compression 22R - minimum	9.0kg/cm² (127.8psi)
Compression - max difference between cylinders	1.0kg/cm² (14psi)
Spark plug	Champion NY11YC
Spark plug gap	0.8mm (0.032")
Max spark plug lead resistance	25kOhm
Distributor heel gap	0.45mm
Distributor air gap (EI)	0.2-0.4mm (0.008"-0.0168")
Distributor damping spring gap (points)	0.1-0.4mm (0.004"-0.0168")
Distributor heel gap (points)	0.45mm (0.0177")
Dwell angle	52°

Last updated 27 Dec 2007