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MG MGB Technical - Early & Late crank pulleys

Can anyone tell me the difference between the pulleys on the early and late cars?
Is it just the position of the timing marks?


I need a new pulley but no where seems to do a pulley for the later cars.
K Goldup

I think that the rubber bumper cars had a much larger diameter pulley.

I am about to fit a late engine to my '67 and will be re-using my original pulley, so the large pulley should be surplus to requirements.

When I say 'about to', I still have a lot of work to do in the engine bay and I haven't even brought the replacement engine home from its storage yet.

Dave O'Neill 2

Three pulleys are listed in the Leyland Parts Catalogue. The 2nd being fitted to 18GG engines i.e. from Oct 68 and for 18V engines up to and including the 75 model year i.e. into the rubber bumper period. The 3rd was fitted to 18V797/798 and later engines i.e. from 76 model year cars. Originally the timing marks were at the bottom, then moving to the top, but this is a factor of crankshaft keyway as well as pulley. Front covers changed at the same times, which indicates the timing marks moved for the 18GG as they had definitely moved before 76.
PaulH Solihull

Crank keyways are all in the same place on the crank. The change is the relationship between the keyway in the pulley and the notch/mark.

FRM
FR Millmore

Just walked into my shop and looked at the 70 MGB engine spare and glanced inside my 80 LE. There's a significant difference in the diameter of the crank pulleys, about 2 inches is my guess. The early engine, an 18GH, is much smaller. Someone likely has more details on the exact engine number matchs. I recall there was a difference in the timing mark locations between the 18GH and later engines of that series. I had a 1971 engine for a spare and recall the timing marks required spotting under the car rather than from above, although the diameter was the same. Getting the wrong pulley would obviously cause some belt fit problems and I'm not sure if the later, larger diameter pulley would even fit with the crossmember clearance of an earlier car.
Rick Penland

Thanks for the replies, does anyone know if there was a difference in the water pumps to compensate for the change in pulley size?

I know the water pump pulleys are the same diameter. If theres no difference I'm going to use the early pulley (and put on my own timing mark)
K Goldup

There are a number of different water pumps. Here is some info from Moss...

http://www.moss-europe.co.uk/graphics/uk/instructions/mgbwaterpumpadvice.pdf
Dave O'Neill 2

This thread was discussed between 19/05/2011 and 30/05/2011

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