This is a slightly random collection of tips and modifications that David Stride and I have found useful in our Tatra ownership. I should point out that I am an enthusiastic mechanic rather than a skilled one, still bemused that the motor goes after my meddling. But at least if I can do these things then anyone should be able to.
CARBURETTORS. One of the major design errors in the 603 engine is very easy to put right but the factory never got round to doing it, though I gather many field mechanics did a modification. The fuel lines are fixed to the carburettor by banjo unions. A very dangerous way of doing it as they have no tolerance, they are either done up tight and don't leak or they are loose and leak profusely, there is no half way stage. It is obviously the wrong way of doing it .(It was the preferred way of the British motor bike industry, at least in that case you always knew about it as your boot invariably got filled up with petrol before the engine caught fire.) It is easy to fix. Make up two fittings either by machining from scratch or modifying the blanking plug that is fitted at the back of the carburettor, (you need a pair from a spare set of carburettors). Drill out the middle and braze in a bit of tube. Rubber fuel line can then be attached to these with nylon clips. A T-piece is then made from the existing tube and a single fuel line goes on to this. These fittings are unlikely to come undone and if the do the will give a warning weep long before they gush. The various screws and bolts around each carburettor also come loose, the correct sealant can help, but basically check them regularly.
FUEL PUMP. This next modification makes life easier, rather than being essential, and that is to bypass the mechanical fuel pump and use an electric one. this enables the fuel line to enter the engine bay by a more straightforward route (from the carburettors straight through the fire wall) This will keep the fuel cooler, essential with modern petrol, and again will lessen the chance of fires. The obvious place to fit a small fuel pump is in the large space where resides the steering rack. Give it a separate on-off switch. This enables the fuel to be switched of before you come to a halt. Hot engines boil off the petrol left in the carburettor, wasteful and dirties the carburettor. It is also useful as a simple check for fuel leaks. Switch it on and wait to hear the clicking stop, an intermittent click after that means a leak. (it is also a warning of running out of petrol as you can hear it hunt when the petrol gets low). Incidentally the fuel tank is so designed that it will empty completely. Whilst you are at it put a canister fuel filter in line before the fuel pump. Apart from its safety aspects an electric pump will greatly help starting with modern petrol. Whilst on the topic of fuel leaks remember to check the drain plug in the bottom of the tank. PS if you want to keep things looking original, then leave the mechanical pump in place but remove the operating plunger.
FAN BELTS. Fan belts are readily available and cheap, so if you are worried replace them frequently. They do not like oil so be vigilant if you have a leaky engine. Check then for alignment with a steel rule across the face of the fan housing. Adjusting the housing in and out as well as checking that it is parallel. Get the correct slack on the belts by adjusting the number of spacers. never have the belt tight. If adjusted correctly they should last for years. DO NOT DRIVE THE CAR UNLESS YOU SEE THE STOP LIGHT COME ON This can be adjusted by altering the tension of the spring in the vacuum sensor. Have it so it goes out when you rev the engine. NON operation of this warning devise can mean a very hot engine and an engine rebuild. The left bank of cylinders is monitored by the generator light. Again check it works when you switch on the ignition and stop if it ever comes on. A broken fan belt sounds like running over a card board box.
SPARK PLUG CAPS, NGK do a long spark plug cover used on motor cycles that is perfect for the job. They stand the heat much better than the Czech plastic plug caps you sometimes find. It can be a little difficult to get the copper lead you need but it is available, again try a motor cycle shop ( the sort that sell old British bike bits.)
BRAKES. If your hand brake is OK you are lucky. The hand brake has a self adjust mechanism (British design) that usually doesn't work. If the screw will co-operate turn it until the pads bite then back it off a bit and replace the split pin. This relies on the adjoining ratchet being able to restrain the tightening nut, which is not always the case. Otherwise you will have to take the mechanism apart and give it a good clean and then hope it works. The best solution would be to junk the ratchet, weld up the nut to the pivot, and adjust without any problems. Apart from the hand brake the front and back callipers are easy to sort out. Pistons and Pads are available but be careful of the "premium" because they are also Jaguar bits, They can be found on many cars, mine are from an Alfa Romeo supplier. I have also sourced a modern-type seal kit (expensive) that should be able to keep the muck out better. If the main fluid reservoir is mounted on the bulkhead then underneath are two rubber elbows. that perishes easily. Replace them by ones from a Ducati 916 or use a longer length of normal brake hose. I find it more convenient to have the reservoir mounted on the side anyway, so have moved mine.
CLUTCH. This is of the over centre type so its not impossible to set it up wrongly. If adjusted correctly you should be able to get your finger under the operating fork and lift it up about 5mm. Get someone to push the pedal down. If completely wrong the operating fork will stay in the up position. You adjust it with a broad blade screwdriver. A couple of pumps on the grease gun to grease the thrust bearing will complete the job RUST. Rain will get under the floorboards so keep an eye on things. A few judiciously drilled holes can save a great deal of later work. There are three pairs of sealed sections that need a hole underneath to let any water out and a hole on top to let condensation out and Waxoil in. They are. The top hat section in the front foot well. A deep section under the rear seat that strengthens the radius arm mountings. And one that rises up at the side of the gearbox compartment, The cable to the starter motor goes up one of these so if the rubber bung at the top has got dislodged it will certainly ship water.
OILCOOLERS. These have to cope with more than they are really capable of so make their life easier. The mounting bolts should be perfectly concentric in the oil cooler, bend the bolts gently with a length of pipe to achieve this. I think oil-coolers can be got of with the silencers in place, but not on my car which has non-standard silencers, even so it takes a bit of jiggling. Make certain the shrouds do not vibrate on the coolers. You are aiming to get the coolers to float on the soft neoprene O-rings. Incorrectly mounted they will leak either through the o-rings or vibration will work harden the soldered construction and cause cracks. I found a good place in Northampton to rebuild them some years ago. I gather they may still do a good job.
LEAKS. This comes under essential because it affects the fan belts, But if its that bad it also impairs the cooling. If you have cooked the engine (see fanbelts!) then oil can piss out of everywhere. Otherwise the leaks are usually confined to a couple of places. One we have just dealt with. The other is the oil filter. This weird device is sealed by a totally hidden rubber gasket. I fail to see how you can fit it without a high possibility of trapping some grit between the gasket and the filter cover. If 10 miles down the road you find you have a leak. Then try and do the job yet again. Far simpler to fit a modern cartridge filter. No leaks and a filter that works, All for about £40 There is another traditional place for an oil leak and this is at the front of the gear box, where the selector rod enters. Adolf Kunz reckons that replacing the oilseal may not cure it as the fault is in the design of the seal. The problem is cosmetic, although it is the road outside our house that now needs the cosmetic surgery. If it worries you then fix up some catch device, I have.
BONNET RELEASE. There is a separate bowden cable that probably is hidden behind the dashboard. Make sure it works, grease it up well as if the main release breaks or jams, then you would be in trouble without this backup. I have needed it twice, once when the cable came adrift, once when a bit of errant camping gear got stuck in the release mechanism.
ODDS & ENDS. Found out the other day that the wheel rims on the back of the car have a different offset to the ones on the front. I can only assume that in the past I have driven the car with different offsets on the same axle. Not a good idea.