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Author Camshaft timing instructions

Registered: 1st May 01
Location: Hurstbourne Tarrant
User status: Offline
24th Jan 03 at 08:16   View User's Profile U2U Member Reply With Quote

Camshaft timing instructions
1 Correct cam timing is essential for optimum performance. Determine true T.D.C. position of the engine by rocking the crankshaft whilst No. 1 piston is at the top of the bore. There will be approximately a 10 degree dwell period, and true T.D.C. will be the centre of the dwell period.

2 Having obtained true T.D.C.then either :-

(a) fit timing disc to crankshaft and set to zero. Now rotate crankshaft clockwise to the full lift position specified for the particular camshaft being fitted. It is at this position that No 1 inlet valve should be fully open. This can be checked by fitting a dial indicator gauge on No 1 inlet follower and rotating camshaft until valve is fully open. Once again approximately a 10 degree dwell period will be shown and true lift will occur in the centre of this dwell period

(b) Leave crankshaft at T.D.C. fit a dial indicator gauge on No 4 cylinder inlet valve follower(if twin cam use last valve)and rotate camshaft to required T.D.C. lift. If twin camshafts are fitted then repeat on the exhaust side. Once correct lift has been set on twin camshaft applications the lobes on no.4 cylinder should be facing towards the centre of the engine

3 Having timed in the camshaft then fit drive belt (correct tension is checked by twisting belt by no more than 90* on the longest length between pulleys) and rotate engine to check that there is no valve to piston contact minimum clearance .060 (1.5mm). In twin cam applications ensure there is no valve to valve contact and then re check camshaft timings repeating 2 & 3 if required.

4. Before starting the engine, turn over the engine by hand to ensure that it turns freely, prime the oil system and check that everything is set to ensure the engine starts straight away. Do not turn over for any length of time on the starter.

5. Once the engine is running do not allow it to idle for the first 20 minutes, Unless running in is required, then follow the running in procedure. Keep the revs to a minimum of 2500 in order to ensure adequate lubrication of cam and followers.

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