4 replies to this topic

[ac427]

A friend has a used EN40B crank for sale. Are they overkill for a large bore road engine project.

 

I was wondering how i could go about checking it for wear and what the measurement tolerance would be before it was declared scrap?

[DeadSquare]

The Turbo Metros didn't have EN40 cranks, so, Yes, for a road car, it is overkill, but nice to have the extra margin of strength.

 

You would need Cooper S or MG conrods.

 

The main bearings are 2" and the big ends are 1.625" easy to measure with a Vernier.

 

The Nitriding is not very thick, and if you grind them down .030", you risk going through the hardened surface layer.  The workshop manual states a maximum of .020".

 

An EN40 crank it too good to be scrapped.

[imack]

Assuming this is a Cooper S EN40B crank rather than an aftermarket one. In addition to the comments above, I'm pretty certain that the crank is only a straight fit into the appropriate Cooper S block due to it having different with main bearings to a normal 1275/1300 crank.

If it's an aftermarket crank, it may well drop straight into a solid walled 1275 block, but the big ends could be either Cooper S diameter or standard 1275 diameter, plus the stroke will need checking.
Also, what stroke is the crank?
970, 1071, 1275?

[Spider]

You also need custom thrusts if fitting an S crank in a Non-S block.

As Deadsquare mentioned, the Nitrididing is on very thin, even at a 0.010" you are through most of it. And after grinding, you'll most likely find it'll have a bend in it.

I find them brittle and out or all Mini cranks, these are the most prone to cracking.

[Cooperman]

For a road engine you really don't need more than a standard crank. However, the A+ cranks are better than the non A+.