7 replies to this topic

[tom1]

HI , can you fit a old cooper s 1275 crank into a A+ block? Is a late A+ crank better than a S one ?

[Artful Dodger]

Yes you can fit it, the EN40B cooper S crank is far superior to the A+ crank. However, the con rod big end journals are thinner on the cooper S crank, due to the material being better and stronger and not needing as much area to support the rod. So you WILL have to fit S rods as well.

[MIGLIACARS]

NOT A LOT OF PEOPLE KNOW BUT THE SPACING ON A COOPER S CRANK  JOURNALS ARE SLIGHTLY DIFFERENT TO A NORMAL CRANK.

 

they can be fitted but will need extra work

 

if you but the 2 side by side you can visually see it

[tom1]

When you say they need extra work, what do you mean ? Is that butt the two cranks side by side ?

 

Thanks Tom

[Artful Dodger]

NOT A LOT OF PEOPLE KNOW BUT THE SPACING ON A COOPER S CRANK  JOURNALS ARE SLIGHTLY DIFFERENT TO A NORMAL CRANK.
 
they can be fitted but will need extra work
 
if you but the 2 side by side you can visually see it

You mean the big end journals are narrower as I said right? The main bearing spacing isn't different as well is it?!

[Cooperman]

Main bearing width is slightly narrower on the 'S' block so specially machined down +0.030" thrust bearings are necessary.

[tom1]

So if I have got this right, my S crank will fit in my new block, see my other topic(100 bhp and how to get there). The only problem being if I need new thrust bearings, I will need to get a set machined down(cost?)

[Ivor Badger]

Have put one in a 1300 block and all it needed was the thrusts machined down, which wasn't that expensive or hard to do.