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by Bob O’Neill
The timing belt is driven by the crankshaft, and turns the cam and the intermediate shaft; indirectly, it drives the distributor.
Sprockets on the cam and intermediate shaft are twice the diameter of the sprocket on the crank, so for every two turns of the crankshaft the cam and intermediate shaft is turned one time. The intermediate shaft is geared to mesh with the driver gear of the oil pump; the slot in the oil pump gear drives the distributor, as the tabs on the distributor fit into the oil pump drive gear slot. The distributor is therefore driven in part by the intermediate shaft. For each turn of the cam and intermediate shaft, the distributor shaft turns one time.
The timing belt should be replaced at 60,000 mile intervals (on some cars, up to 105,000 miles is recommended, but this may be imprudent).
If, after 60,000 miles, an inspection of the timing belt indicates little wear, it could be used but should be checked at every oil change after the 60,000 mile interval. However, because the procedure to replace it is easy and because these belts are not expensive, the belt should be replaced at the 60,000 interval.
These engines are non-interfering which means that should the belt snap while the engine is running the valves will not contact the pistons. But to prevent being stranded while driving, replace the belt every 60,000 miles. While you’re at it, replace the other drive belts too. (Editor’s note: the process for the dual-overhead-cam engines known as the "Turbo III" is somewhat different and more difficult. These engines are fairly rare and were only installed in the Daytona R/T, Spirit R/T, and certain cars in Mexico.)
Fig #1(notice that in the illustration the marks are not exactly lined up)
(note the tool on the left and a 15mm wrench
to tighten the attaching bolt on the right)
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