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MG MGB Technical - Timing Chain Replacement

1971 MGBGT - one of the very last duplex chain 18V engines.

The next jobs are head gasket (weeping water to the outside world) and noisy timing chain. The books say I'll need to move the steering rack out of the way to get the crank pulley off.

Given that the plumbing (including exhaust) will already be disconnected for the head job, is it better to move the rack or undo the front engine mounts and lift the engine a bit?

Sorry if this seems a daft question, but I'd rather ask than waste time once I get started.

Kevin
Kevin Poole

Kevin,

I don't quite remember exactly what I did when I was changing the cam timing on my 68 BGT, but I know for sure that I did not remove the rack to get the crank pully off, and my exhaust was still connected.

Charley
C R Huff

Kevin You can leave the steering rack connected to the tie rods, just remove the four bolts holding the rack to the chassis and the lower steering universal bolt and slide the rack out of the way. Mark the splines on the u/joint so you can line it up on reassembly. I usually make sure the steering is dead straight ahead just in case. If your not pulling the cam you should not need to lift the engine or undo the mounts. Denis
Denis4

Mine is a 71 roadster. I did not have to touch the rack or colomn to replace the timing chain. Removed the rad. and fan blade. This gave enough working space.
Trevor Harvey

As we can pull the engine straight forward off the gearbox input shaft and it clears the rack I would have thought there was enough room to get the pulley off the crankshaft.

A UK 71 should have the earlier collapsible column in which the inner can move up and down inside the outer quite a bit (or at least mine does!), just undoing the rack to cross-member bolts without undoing the UJ should give you a bit more room if you need it.
Paul Hunt 2010

When I fitted the Moss pulley that came with their supercharger system, their instructions said to drop the rack or raise the engine so that the damper would clear the rack. On my '67, I decided it was easier to drop the rack. Looking back it would have been easier to loosen one of the motor mounts instead. RAY
rjm RAY

Thanks for all the advice. Fortified by the confidence thus given, I just got on with it, and had plenty of clearance to remove the pulley without moving the rack or the engine.

I used a socket and 24" breaker bar wedged against the wing and wired in place, and a quick burst on the starter to free the crankshaft bolt, and an impact wrench on the camshaft nut (cf the chisel a previous owner had attacked it with). The chain cover washers were all standard, not the fancy shaped ones, and one of the set screws was M6 thread. I wonder what I'll find when the head comes off?

Thanks again, gentlemen.

Kevin
Kevin Poole

The chain cover washers should be round on your engine - the shaped ones are only found on the very early covers which do not have the raised moulding between the holes.
Chris at Octarine Services

This thread was discussed between 29/03/2010 and 31/03/2010

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