Triumph Stag
Published: 17th Jun 2011 - 0 Comments - Be the first, contribute now!
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Keep on top of the cooling system and you’ll be fine with this car
Engine
Overhead camshaft V8. Cast iron cylinder block with aluminium cylinder heads. 2997cc, 146bhp IMPORTANT NOTE: Rover V8 engines were a popular alternative retro-fitchoice; if your Stag is so equipped, see separate section relating to this unit.
Valve clearances
Inlet: 0.008 to 0.010in. (0.20 to 0.25mm.). Exhausts: 0.016 to 0.018in. (0.41 to 0.45mm.). The valve clearances are controlled by shims; so altering the gaps is timeconsuming. However, the gaps usually only need to be re-set re-assembling after with an engine rebuild or ‘top end’ overhaul, or if the valve gear becomes excessively noisy. In each case, with the cam lobe uppermost (directly opposite to the cam ‘bucket’), apply eeler gauges between the cam bucket and the ‘heel’ of the cam.
Ignition
Firing order: 1-2-7-8-4-5-6-3 (No. 1 cylinder at front; odd numbers on right hand cylinder bank; even numbers on left hand bank).
Spark plugs: Champion N12YCC equivalent. Gap 0.025in. (0.63mm.). Check/clean every 6000 miles or annually (whichever comes first); renew regardless every 12,000 miles.
Contact points: Gap 0.014 to 0.016in. (0.36 to 0.40mm.), corresponding with dwell angle reading of 26 to 28 1 degrees (single contact breaker models), or 29.5 to 33.5 5 degrees (twin contact breaker versions). In each case, check/clean the contact points every 3000 miles or annually (whichever comes first); renew regardless every 6000 miles. Distributor cap, rotor arm and high tension leads: Every 3000 miles, clean and check, ensuring especially that all connections are in good condition.
Distributor - mechanical aspects: Every 3000 miles, lift off the rotor arm and apply a few drops of engine oil to the moving contact pivot, distributorshaft/cam bearing and mechanical advance mechanism (through holes in distributor’s baseplate). SPARINGLY apply grease to the distributor cam.
Timing (static): Use 12 degrees before top dead centre (BTDC) as a starting point; refer to timing marks on the crankshaft pulley and timing case.
Timing (dynamic): 16 to 20 degrees BTDC at 3400 rpm, with vacuum pipe disconnected.
Note: These timing settings should be regarded as initial starting points. When using modern,low octane fuels, and currently available low compression pistons, further fine tuning may be required to ensure that the engine is running at its optimum setting.
Fuel system
Every 3000 miles or annually (whichever comes first): Scrutinise all fuel system pipework and connections. Check/top up carburettor dashpots with SAE 20 oil.After all ignition settings have been checked/set, and with the engine at normal operating temperature, re-adjust the carburettor mixture/idle speed settings (employ proprietary doit- yourself equipment for synchronising the twin carburettors). Aim for an idle speed of approximately 700-800 rpm. Renew the air filter elements at least every 12,000 miles (or sooner if visibly dirty; examine them every 6000 miles). At the same time, ensure that the breather pipework is unobstructed.
Lubrication
Engine oil: Ideally change the oil and filter at least every 1500 to 3000 miles or annually (whichever comes first; change more frequently if the car is used mainly for short journeys). Use premium quality, SAE15W50, 20W50 or 20W60 oil. Please dispose of the old oil in an environmentally friendly manner – local councils provide waste oil collection points. Drain/refill capacity (including filter), approx: 9 pints (5.11 litres)
Gearbox oil: Check the lubricant level at least every 3000 miles or annually (whichever comes first); investigate if frequent topping-up is required. Use SAE90EP oil in manual gearboxes and ‘AQF’ automatic transmission fluid in automatic units. Approximately every 24,000 miles, drain the old oil (after a long run to warm the oil), and re-fill with fresh lubricant. If overdrive is fitted, every 12,000 miles remove/clean the gauze filter at the base of the unit.
Manual gearbox capacity (from dry): 2.25 pints (1.28 litres), or (early cars) 3.75 pints (2.13 litres) if overdrive is fitted; but 2.66 pints (1.51 litres) for later examples.
Automatic transmission capacity:
Type 35 (early cars), 11.5 pints (6.53 litres). Type 65 (later examples), 14.25 pints (8.09 litres) including oil cooler.
Final drive oil: Check the oil level at least every 3000 miles or annually (whichever comes first); investigate if frequent topping-up is required; use SAE90EP oil. No drain plug is fitted; please note that there is no requirement nor facility to regularly change the axle oil. Capacity (from dry): 2 pints (1.14 litres).
Other aspects: Every 3000 miles/annually (whichever comes first): Clean/re-grease the handbrake operating linkage, and check the protective gaiters at the backplates. Note: If the gaiters split and the handbrake ‘scissors’ assemblies which they protect seize, the selfadjusting mechanism will be unable to operate. Re-grease the steering rack (after screwing in a grease nipple) and propeller shaft couplings (manual transmission versions only). Re-lubricate the hinges and catches.
Brakes
At least every 3000 miles or annually (whichever comes first), check the state of the front brake pads and discs, also the rear shoes, cylinders and drums (remove the drums for a proper inspection), plus the fixed brake pipes, flexible hoses and master cylinder. Renew any ailing components straight away.
NOTE: AVOID INHALING ANY DUST FROM THE PADS/SHOES – IT MAY CONTAIN ASBESTOS Adjust the rear brake shoe to drum clearances
as required, then check handbrake operation and re-adjust the cable length if necessary. Check the tightness of the front caliper securing bolts. Check/re-lubricate the handbrake mechanism. At least every two years, change the brake fluid.
Cooling system
NOTE: It is VITALLY IMPORTANT to carry out regular maintenance to keep a Stag’s cooling system in good condition, or reliability will be compromised and possibly overheat. The engine may be seriously damaged and will then be very costly to repair. Throughout the year, and even if the car is not on the road all the time, use top quality anti-freeze mixture containing corrosion inhibitors, and ideally employ distilled or de-ionised water (rather than tap water) in the cooling system. Every 3000 miles/annually, closely check the radiator, all hoses and the water pump/fan. At each service, look closely around the base of the ‘V’ between the cylinder banks, especially towards the rear end of the engine. Look for evidence of leaking coolant and establish/rectify the cause.Leaks may be from the core plug located between the coil and distributor base, a time-expired water pump seal, a failed cylinder head gasket (check for overheating too; the aluminium cylinder heads may be warped – if the engine overheats it may already be damaged), and the gaskets/’O’ ring seals between inlet manifold and cylinder head. At least every three years, drain the entire system, remove the thermostat and reverse-flush prior to re-filling the system with fresh anti-freeze solution. Note: Abide by the dilution recommendations of the anti-freeze manufacturer; these are usually printed on the container. Cooling system capacity, including heater: 18.5 pints (10.51 litres).
Retro-fitted stags
(Note: Mid-1970s Rover 3.5 litre unit taken as example; please consult manufacturer’s data relating to the specific engine used in your vehicle). Engine type: Aluminium cylinder block and heads; central camshaft. Overhead valve (pushrod). 3528cc, 143bhp.
Spark plugs: Champion L92Y or equivalent, gapped to 0.025in. Contact breaker gap: 0.014-0.016in. (corresponding with dwell angle of 26-28 degrees). Firing order (L = Left cylinder bank; R = Right bank): 1L-8R-4R-3L-6R-5L-7L-2R.
Timing: 6 degrees at 600 rpm, with vacuum pipe disconnected (assuming minimum fuel octane rating of 96).
Engine oil capacity: 8 pints (plus filter 1 pint); use high quality, ‘full-bodied’ multigrade oil. Ideally change engine oil and filter at least every 3000 miles or annually (whichever comes first).
Carburettors: Use proprietary do-it-yourself tuning aids to balance/tune twin S.U. carburettors. Only re-adjust after checking/setting ignition system, and with engine at its normal operating temperature. Aim for idle speed of 600-650 rpm.
Sundry items
Every 3000 miles or annually (whichever comes first): Check front hub bearing condition and free play (re-adjust as required). Scrutinise the steering rack gaiters for splits/leaks. Examine the alternator drive belt and re-tension if necessary (aim for ½ in. or 13mm deflection at the centre of the longest belt run). Assess the clutch operating system hydraulics for deterioration/leaks. Check the cleanliness and security of all electrical connections; inspect all wiring for deterioration. Inspect all running gear components and suspension mounting bushes. Look closely around the underbody for damage and rectify any paint/underbody sealant blemishes discovered. Check all driveline universal joints for wear/damage. Inspect the exhaust system and its mountings.
Best Mods
- Accepted mods to the inlet and exhaust manifolds, an American Holley carb and electronic ignition can yield up to 175bhp for reliable road use.
- The Stag uses an unusual twin cb points set up and its always a good move to ditch the arrangement for points-less electronic ignition, which also improves running and economy.
- Replacing the Stag’s radiator is always a good move, even if it isn’t leaking. While you’re carrying out such wise preventative maintenance consider fitting an uprated core from the likes of Radtec etc along with an electric cooling fan.
- A front ‘bib’ body spoiler also improves the cooling capabilities plus makes the car more stable at speed.
- For the suspension fit polyurethane suspension bushes (these bushes not only improve the feel of the Stag plus will never need changing again), Spax adjustable rear dampers and 30 per cent uprated front strut inserts; this will improve the handling no end. One stage further would be a lowering kit to lower the car by approximately 1.25 inches – although it’s not really essential for road use.
- When it comes to fitting a more reliable engine, most go the Rover V8 route although the Triumph straight six can also be installed and is an easier fit, naturally. The 2.5-litre engine is also a lot lighter than the V8 and so suitable saloon front springs will have to be used to compensate or the handling will suffer.
Top Tips
- The biggest worry is that vulnerable V8 overheating, often with terminal results. Always keep the antifreeze concentrate up to 40 per cent and replace every three years to also keep the corrosion inhibitor up to strength. Any suspect componets such as a dicky thermostat, failing rad cap or tired hoses should bereplaced at once.
- There’s a variety of cooling mods devised over years of expereince – contact the Stag Owners Club for best advice. Post ‘72 cars featured a modified radiator and header tank arrangement, while many owners have devised their own set ups.
- The Stag uses a TR6-derived transmission and can suffer from clutch problems, although the real dranger is the quill shaft housing (linking the diff’s casing to the rear subframe) failing. If it breakes it will cause serious damage.
- Noisy rear wheel bearings are usually more serious than you think, as the housings are also damaged at the same time.
- Examine the underbody outriggers and strengtheners, jacking points and undersides of the sills, plus all metalwork around the suspension and sub-frame supports. Inspect with a fine toothcomb beneath the rear seats. Other rot areas include the ‘A’ posts, windscreen pillars and bonnet hinge supports.
- The metal behind and beneath the headlamps is rustprone but easy to miss. Less serious rust attacks the wings wheel arches, and battery tray. At the rear, check the boot floor, inner rear wheel arches, boot lid and rear valance panel.
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