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The history of the Triumph Herald engine that is used to power the Amphicar.

The Herald engine started as 948cc in 1958. It was uprated to 1147cc (1200) in 1961 at which time is was considered the best small engine in the world for power/weight ratio and ability to run cool. This is why it was chosen for the Amphicar. In 1964 a more powerful version was developed called the 12/50. In 1968 the 1300cc version called the 13/60 became available followed by the 1500cc in 1971. The Spitfire used the same engine, normally with twin carburettors and higher compression. Up to 10:1 instead of the normal 8:1 or 8.5:1  Spitfire engines can be used in Amphicar but do not run as well at low speed, because of their more "racey" camshaft.

As you will know, the chassis on the Herald and the Amphicar is different. Amphicar designed the engine mounting bracket part number 1-01-02 so it would fit Herald engines that were used in cars with a mark 1 Herald Chassis. From 1965 a mark 2 Herald Chassis was used and the mounting points for the engine were changed to reduce vibration. Because of this almost all Herald Engines will need to have the front plate changed for the early type Amphicar type part number 1-02-24. This is not difficult to do but spare front plates are rare.

Identification.

All of these engines have a serial number stamped on the block that starts with 1 or 2 letters:

G 948cc

GY 948cc

Y 948cc

GA 1147cc

GB 1147cc (export)

GE 1296cc (small crank)

GD 1147cc (50hp)

GK 1296cc (large crank) OR Amphicar 1147cc

FC 1147cc Spitfire

FD 1296cc Spitfire

FK 1296cc Spitfire

FM 1500cc Spitfire

NEW - More engine ID info at the bottom of this page.

Type 1 - GK engines,

These are Amphicar 1147cc or Herald 13/60 (1296cc). Triumph made a mistake and used the GK numbers for a second time in 1968 on the engine in the Herald 13/60. Two engines might have the same number. Be careful ordering parts from Triumph suppliers, they do not all know this. Amphicar GK engines will have a 6 port cylinder head, flat core plugs, a spring clutch, a water pump housing with temp sensor on top and an engine number less than GK5000HE. Triumph GK engines will have 8 port cylinder head and diaphragm clutch. If the engine is apart you can measure the cylinder bores. The Herald GK engine is explained in Type 6 below. The Amphicar GK engine is almost identical to the Herald GA engine, Type 2 below.

Type 2 - GA Engines,

These are engines before engine number GA190341HE These are the most common, used in Herald 1200. Power is same as Amphicar about 40 BHP. Only difference from Amphicar was water temperature sensor, which was moved to the side to clear the bonnet of the Herald.

Type 3 - GA Engines after GA190341HE and GD Engines after GD110001HE,

These are similar to GA except have more power, 48BHP, this is due to higher compression ratio 8.5 to 1 instead of 8.0 to 1 and a different camshaft. These engines are the best type to use in Amphicar, they still run cool and are very reliable. Later versions have bucket type core plugs which do not leak.

Type 4 - GD Engines up to GD103470HE,

These were used in the Herald 12/50 (50=50HP or 48BHP). These are the same as type 3 engines except they use an exhaust manifold that is more efficient but not suitable for Amphicar and must be replaced.

Type 5 - GE engines 1296cc,

These have the small diameter crankshaft and can be fitted to Amphicar. They need a different carburettor and manifold because they use and 8 port cylinder head. This is difficult to do. These engines run hotter than the 1147cc engines and are not as reliable. They give an extra 9BHP but for most Amphicar owners this is not worth the trouble.

Type 6 - GK engines 1300cc and 1500cc,

These have all the problems of a type 5 engine but because they use a larger crankshaft than the 1147cc engine the flywheel has to be re-drilled and balanced. The 1500 engine in particular runs very hot and cause many problems in Amphicar.

Spark Plugs,

Be careful with spark plugs. They are different between the 1200 and 1300/1500 engines. If you use spark plugs from the 1300/1500 in the 1200 you will burn a hole in the piston. The correct spark plugs for the 1200 are Champion L87YC and for the 1300/1500 they are N9YC.

Distributors,

These have the date and part number stamped on them. The part number for the 1200 is 40791, for the 1250 is 41230 and for the 1300 is 41127.

How to spot a good engine,

Crankshaft movement front to back (end float) must be checked, if this gets very bad it will cause strange clutch problems and eventually will totally destroy the engine. The manual shows how to check for wear. This is the most important thing to fix when overhauling these engines.

Wear on starter ring gear 1-03-11a is a good sign of engine use, check for broken teeth. The ring gear can be turned around to extend life (see manual)

Front crankshaft pulley, 1-03-07, this is made of Iron, if the engine is dropped this can crack or break, check carefully, also many engines leak oil from the seal behind the pulley.

Rear engine mounting plate 1-02-34 (the one with the hole for the starter motor). Check it has not been bent.

Sump (oil pan) 1-02-35. Engine is sometimes dragged around on this, check it does not have holes or is dented. It is a good idea to remove it and clean it out.

What needs to be done to fit a Herald engine in an Amphicar.

For almost all Herald engines the front plate (with the engine mounts) will need to be changed. The type used on Amphicar 1-02-24 is the same as mk1 chassis Heralds and some of the TR3 or TR4 cars. They are rare so you might have to use the old one on an Amphicar engine. To change it you need to remove the front pulley (38mm socket), then the timing cover 1-03-24 and chain (be sure to mark it with paint first !) and then the timing gear wheels. You can then unbolt the plate.

When putting everything back together you will find that the hole in the Amphicar chassis plate for the camshaft is smaller than the hole in the original Herald chassis plate. It is easy to fix this by enlarging the hole slightly with a file. Be careful when fitting the timing chain and if possible fit a new oil seal 1-03-25.

Another thing you need to do is to change the cylinder head studs 1-02-11 on the front and back where the Amphicar exhaust bracket fits. These are longer than the ones used on the Herald Engine, again it is best to use the original Amphicar ones.

Water hoses for the heater, Triumph are 1/2 inch, Amphicar are 5/8 inch (19mm). The nozzles where they fit into the engine will need to be changed, 9-29a-23.

Water Pump Housing 1-04-01a. On the Triumph engines the holes for the temperature sender units are on the side, not on the thermostat cover 1-04-31. Do not use the Triumph sender. The Amphicar one fits the same way and can be screwed into the side. If you do this it is much easier to find a thermostat that fits.

Oil filter, try and use one with a non return valve so that the oil does not drain out when the car is stopped. Almost all of these engines rattle because of lack of oil pressure when started from cold.

The Carburettor is fitted the other way around on the Herald, just turn it around.

Some engines come from the 12/50 which use a different manifold, no problem - just replace it with the 1200 or Amphicar manifold 1-05-06.

There are 2 types of clutch plate used on the Herald, Spring and Diaphragm. You will see the difference. Only the spring type can be used on Amphicar. Also remember the Herald friction plate is different because the clutch centre 1-12-11 is special for Amphicar.

Other points,

An alternator can be fitted to the engines quite easily, they are made by Lucas and used on later 1300 and 1500 engines. As well as the Alternator be sure to get the Triumph mounting block. The only problem is that to fit an alternator the car must be changed to negative earth.

Removing the cylinder head. If it does not come loose as soon as all the nuts are removed do not hit it with a hammer, Instead remove the studs on the exhaust side of the head by locking two nuts together (after soaking in penetrating fluid). These studs tend to rust in and if the head is hit with a hammer or levered with a screwdriver it can be damaged.

Dismantle the valve gear and check carefully, clean carbon off the valve stem. It is often a good idea to grind in the valves. See section on Lead-free fuel

Do not overtighten sump bolts when reassembling or sump will bend and leak

Check and clean oil pump, it is unusual for them to be worn.

These engines were not designed for unleaded petrol. Lead stops the exhaust valve seats from wearing. The unleaded kit solves this problem. It is also OK to use unleaded 50% of the time in an unmodified engine. The original exhaust valves wear quickest when they have been ground (machined) and are better once they have been used for some time and have a build up of carbon. If you use unleaded in an unmodified engine check the valve clearances often. If they decrease (close up) start using leaded again.

If you want a stainless steel exhaust for Amphicar, Bells in Swindon can make them they are very good but cost about £180. telephone 01793 619234 fax 01793 532946

ENGINE INFO:

Thanks to John Kipping for the following:

Engine numbers
GA Herald 1200                )
GB Herald 1200 Export         ) Similar to Spitfire FC engine
GD Herald  1200 50 BHP engine )

GE Herald 13/60 )
RD 1300 FWD     )  Similar to Spitfire FD/FE engine   
RF 1300 FWD TC  )

GK Herald 13/60       )
DG Toledo 1300        )  Similar to Spitfire MK IV FH/FK engine
DH Dolomite 1300      )
FL Spitfire IV Sweden )

WB 1500 FWD                       )
YB 1500 FWD                       )
YC 1500 RWD/Dolomite 1500 )  Similar to Spitfire 1500 engine
DM Toledo 1500 (Export only) )
DS Toledo 1500 (Export only)  )
FP Midget 1500                     )

Note 1: All 'Triumph' 1500 recon engines appear to have the DM prefix with a suffix ESS
Note 2: All 1500 blocks will take a 1300 (large bearing) crank, 1300 engines up to 1975 will not take a 1500 crank.

And thanks to Eric Kieboom for the following information: