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MG MGB Technical - crankshaft size 183

On finishing rebuild , and attempting to fit pulley to front of I find the crank o/d is 80 though bigger than another 18 engine and so the pulley does not fit . Any ideas ?
bxnsphjii

On a 5 bearing 18V, the nose of the crank is nominally 11/8" i.e., 1.125" but realistically a couple of thou smaller!
Allan Reeling

Wrong pulley or wrong crankshaft ;)

Seriously, which engine?
There are at least three pulley part numbers.

Best Of...
MGmike
M McAndrew

The two pulleys I have fit on a 72 crank and the parts book refers to two different pulley sizes over all- the casting no on the block refers to an 18 v and I have fitted standard size main and big end bearings.
In the course of the rebuild a magic mouse ate the original pulley .
So what do I have ?
And what can I do ?
bxnsphjii

Even though your engine casting number indicates that you have an 18V block, any crankshaft from '65 to '80 will interchange between five main bearing blocks. It would appear that you have one of these other crankshafts fitted to your block. RAY
rjm RAY

Hmmm a puzzler...

AFAIK all the cranks have the same size nose and the differences in pulleys is the outer diameter.
Perhaps someone will come a long and confirm.

What do you have? Who knows! From what you've said we would need a bit more info, like a part number off the crank.

As to what you can do...
A few options come to mind
1, find the magic mouse and give him a good kicking for moving your original pulley :)
2, have one of the pulleys you do have machined to fit
3, use a different crankshaft

let us know how you solve it.

Best of....
MGmike
M McAndrew

Think I'd be inclined to mic the nose of the shaft and then get a pulley machined to fit
Iain MacKintosh

The 18v had 2 different size pulleys I think, 132mm and about 150mm. The size increase seems to have happened when they went from mechanical to electric fan. But the nose dia remained the same 1.125".
Mic it up and see what you have.
Allan Reeling

I don't think it is a good idea to mix Metric with imperial sizeing, when the cars were built I would have thought they would have been imperial. Just a thought.!!

Graham
GJ Barker

Graham, if you want to be pedantic, 5' dia and 6' dia.. Neither are that critical, the nose dia is the important one and that IS imperial!!
As far as I can determine the 18v engine, without major changes, was used across the Leyland empire, Marina, Sherpa, probably also the east/west applications as well, so where the "big nose" crank came from……who knows………..someone, no doubt.
Allan Reeling

I've heard O series crank is interchangeable but have never tried it myself.
And A series have smaller ID of the pulley.
Paul Walbran

This thread was discussed between 08/08/2014 and 09/08/2014

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