Many parts of the Rivett can be tuned and modified, either to the player's liking or to generally avoid damaging the engine. Most of these tuning tasks can easily be done by hand, with patience.
If the player does not quite trust their own skills, they can have Fleetari do some of these by paying him (order engine tuning from the service brochure where noted).
A poorly tuned belt can snap and break, forcing a trip to PSK for a new one. Before tuning, make sure the car is off. Using the screwdriver, unscrew the one screw on the alternator, then hover over the alternator and scroll as far down as possible. Once it will not go any further, scroll up two times, then retighten the screw that was unscrewed before.
Having the crankshaft aligned is very important to the engine.
The timing won't get messed up if you keep scrolling the bolt once the belt is on — the timing stays put. Alternatively, Fleetari can do the engine tuning via the service brochure. The timing cannot be done while the timing belt is still attached.
The camshaft sprocket works in tandem with the crankshaft pulley, as they both use the timing belt. The camshaft sprocket must be properly adjusted before installing the timing belt. The camshaft sprocket's arrow must be aligned with the bolt. Using a 14mm tool, bolt in the camshaft sprocket and continue scrolling until the arrow pierces the bolt. Fleetari can also do this via the service brochure.
Tuning the rockers takes time, as it requires tuning every single valve on the cylinder head.
Camshafts have 3 zones:
The backfire zone is always from 0 clicks to a certain number. If the car backfires (in an AFR between 10–15) you have to scroll up; if the valves make ticking noises you have to scroll down. The sweet spot is therefore always between the backfire zone and the ticking zone.
Both the stock and double carburettors are usually best tuned while the engine is running, and can be easily tuned by the player if they've bought the AFR gauge from the parts magazine. The AFR gauge shows the current air-to-fuel ratio.
The fuel mixture is adjusted with the mixture screw on top of the carburettor using a screwdriver:
If you don't care about fuel economy and want more performance, aim for an AFR reading of around 15. If you want to pass the vehicle inspection emissions test, run the engine at around 14–15 AFR — but only when the engine is warm.
Getting the ignition timing right is important for the engine. If poorly tuned, the car stalls frequently, revs up sluggishly, and makes a distinct, faint chirping sound while idling.
Each scroll upwards adjusts the distributor spark timing by -0.2, each scroll downwards by +0.2. Factory spec, as tuned by Fleetari, is 14.75.