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Part 5 The Cooling System
This is another job that can be completed, off the car, before the major part of the conversion and a trial fit carried out by only removing the TR7 radiator. As the TR7 was originally
designed to incorporate the Rover V8 engine. the conversion of the cooling system to V8
spec is basically a nut and bolt exercise. However, as some of the original TR8 parts are no longer available, it is often necessary to modify existing parts.
Originally the TR8 was fitted with two alternative cooling systems: 1) Non Air Con type -which incorporated a fan and viscous
coupling fitted to the crank-shaft pulley, or, 2) Air Con type -which incorporated twin electric fans on a framework between the radiator and engine. In both cases, the original radiators are no longer available.
Similarly the viscous fan mounting cone and the electric fans are now NLS at Unipart. However all the leading Triumph suppliers can offer a re-manufactured version of the Non Air Con type: bracketry .This will
enable the radiator to re fitted to the car in the correct position but without the benefit of the forced cooling system offered by BL. This is the simplest method and Rimmers now offer a complete kit for this
application. The radiator, although offered to TR8 specification. is approximately 1/2" deeper than the original but does not cause a problem in this application. Regarding the viscous fan arrangement, this
again is available from Rimmers, with the exception of the crankshhaft extension drive ERC 1519. However, I have managed to find someone who is prepared to re-manufacture- this part for about £50. Therefore, the
original TR8 system can be incorporated into the conversion. As an alternative, the usual Kenlowe fan kit can re mounted on the front
of the radiator, but make sure it is rotating in the correct direction -air should be drawn in from the front of the car and blown
over the engine.
As an alternative, I would like to suggest a method that I have used for mounting the radiator, and the fitting of electric fans and
ancillaries.
First the radiator itself. The early FHC's up to VIN200000 were fitted with radiators having the top hose exiting from the left side
when viewed from the driver's seat and the bottom hose exiting from the light side. This, of course, is the same configuration as the TR8, but the hose diameters are different. To overcome this I contacted my local
radiator repair specialist. First we looked at the comparative flow rates of the TR7 and TR8 radiators, there was only a small difference. Next the diameters of the TR8 (SD1) hoses were compared with the TR7, again
bearing in mind a reasonable safety factor built into the radiator it was decided that the TR7 outlets could be sleeved without causing an unacceptable restriction to the flow. Initially we had thought of
unsoldering the existing outlets, but by fitting larger ones it was felt that the strength of the side tanks would be locally reduced, so the correct diameter sleeves were fitted. At the same time the radiator
should be fitted with a new core to ensure there are no restrictions.
We found that the TR7 Aircon 3 row supergill core with 14 fins/inch to be quite adequate. The next stage was to fit a threaded boss
to the left hand top side of the radiator to enable a TR8 type temperature sensor to be fitted, the original is still available under TKC5532 but I have found that its temperature range was incorrect so I bought an
after-market sensor with a range of 82-92'C. These are freely available and fit a standard sensor boss. The assembly was then pressure tested prior to fitting to the car. Pricewise, fitting the radiator with a new
core and carrying out the mods cost approximately £130 and the sensor £11 -not bad for peace of mind!
The partial flow tank causes no problems as, again. the tank and bracket fitted prior to VIN200000 were on the same side as the TR8
configuration. Although not now available from BL, a little diligent searching in a scrap yard produced the goods. It is only necessary
to drill three holes in the correct position in the right hand inner wing and bolt the assembly in place. If the correct tank and
mounting bracket cannot be located then the existing one can be used but the mounting bracket will not sit squarely. The hose from the tank to the radiator is a little more difficult but Henry Ford came to the
rescue with a suitably sized water hose incorporating a 90 degree bend. The final job is to move the low water level warning wire to the tank from the left wing to the right one. Now we will consider the brackets.
The main one that locates the top of the radiator to the body of the car and also contains the mountings for the two (air-con) fans is still available from Unipart under P/No. PKC249 at £23.50. The lower bracket,
which holds the bottom of the radiator in place and also locates the lower end of the fan mountings, part number RKC3112, is now NLS. However all is not lost, Rimmers sell the re-manufactured equivalent UK spec
bracket P/No. RKC532 which will fit with some
modifications. The major difference between the UK and Air-Con spec brackets is a variation in height of approximately 1",
therefore it will be necessary to cut 1" out of the vertical side frames and re-weld. Great care should be taken when carrying out this modification as this bracket holds up the radiator and mates with the fan
bracket, so the actual dimension should be determined with some accuracy .The bottom of the fan bracket is attached to the lower bracket via two weld nuts. The correct position of these will be established when the
radiator assembly is bolted in place on the vehicle. A bonus from using this fan bracket is that the mountings for the coil and the Ballast Resistor are already in place. (NB: Unfortunately, Rimmer Bros radiator
CAN'T be used as it is 1/2" deeper.)
Next, the electric fans - again these are no longer available from Unipart, but the ones found in the Austin Allegro have proved to
be a suitable alternative, having only a slightly smaller diameter on the blades but a similar mounting arrangement. To mount them in the fan mounting bracket, it is necessary to fit a carrier plate over the
existing mounting holes and re-drill new holes as required to accept the new fan studs. Once this has been done the fans should be tested, not only for correct operation, but also for correct rotation. Air should be
sucked through the radiator and over the engine. If this is not happening, reverse the wires on the fans +ve to -ve. Finally, before fitting the fan bracket and radiator together, a length of rubber sealing
should be fitted round each fan cage, again not now available, but the sealing rubber from the boot surround is very similar and can be used. This obviously makes a seal between the fan
and the radiator so that all the air must re drawn through the radiator. The complete assembly can now re bolted in place (not
forgetting the top and bottom radiator mounting rubbers).
Finally, the wiring of the fans. As I am no automotive electrician, I left this to a friend who is qualified in this field. This
ensured that a good safe system was devised with fuses in the circuit and the correct sized wire used. Remember, a bodge job can be easily done, but if the wiring is overloaded then not only the fan circuit but also
the whole car could catch fire. The system is in two parts, each running a separate fan. Fan no.1 fitted to the left side of the radiator operates automatically via the temperature sensor on the radiator. (NB This
fan will run on after the engine is switched off to assist cooling and help combat fuel vapourisation that sometimes occurs after a prolonged run and quick restart on the V8). Fan no.2 operates manually from a spare
switch on the dashboard switch panel (a headlight or footlight switch could be used as these include a warning light, this enables the second fan to be employed only if the
engine temperature becomes too high whilst idling or in heavy slow moving traffic -I would not expect this fan to re used under
normal circumstances, but it should be exercised from time to time. Regarding the relays (Lucas type: 28RA or equivalent), these should be mounted near the fans but in a position where they can be easily maintained
-on the TR8 they were fitted to the LH headlight mounting bolts.
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