What crank do I have

[Russ]

I have searched the forum for "Large Journal Crank" info, as I do not know what a large journal crank is, but am no wiser. Can you please tell me what a large journal crank is.
I have a 51 A10 which I have just stripped down. What crank will I have. Also the conrods have matched numbers stamped on them, however, the numbers on the left rod are not anywhere close to the numbers on the other. Would an engine have left the factory with conrods with matched numbers being similar to one another?

[Briz]

The differences are; the small big-end journal is 1.4375" and the big journal is 1.6875"
On the SJ, the flywheel is attached by a flange with numerous bolts. On the LJ, the flywheel is held on with 3 radial bolts, one of which retains the sludge-trap internal tube.
Unless its had a swap, a '51 will have a small journal crank.
Different rod part numbers may be because the LH rod has a small oil drilling pointing up towards the piston.
*edit* the numbers on the rod & cap are to match one to 'tother. Different rods will most likely have different numbers.

[Russ]

Briz, thanks for that info.
Russ

[trevinoz]

Then there's the LJ used on the Road Rockets which is different again.
I wouldn't worry about the difference in numbers on the rods but just make sure the left one has the hole through the side into the bearing.

Trev.

[A10Boy]

In what way is the LJ in the Road Rocket different to the other LJ cranks? Do you mean that humongously heavy thing?

[trevinoz]

That's the one, Andy.

Trev.