Ford Crossflow crank/rods journals

[carlt5]

Can you use narrow journal rods on a wide journal crank
I have been offered a wide journal long stroke [85mm] crank
but have narrow journal steel rods

cheers

[Pumaracing]

No of course not. The narrow rods would have 3mm side float in a wide journal crank and rattle about like a dick in a drainpipe.

[carlt5]

Pumaracing said:

No of course not. The narrow rods would have 3mm side float in a wide journal crank and rattle about like a dick in a drainpipe.

even with pressed gudgeon pins and ptfe buttons

[Pumaracing]

If you locate the little end instead then yes. The Peugeot Mi16 does this for some arcane reason using pistons with bosses accurately machined for the width of the rod plus a few thou clearance and big ends with loads of side clearance. I've always wondered what the engine designer was thinking to go out on this particular limb.

You can also use washers either side of the rod little end to adapt to this method BUT beware, the sides of piston bosses will usually be angled to allow extraction from the casting or forging tool so a machining op will need carrying out to clean these up vertical and then the washer thickness can be calculated.

Buttons on the gudgeon pin could be used I suppose if you fit the pin very precisely but the piston boss method would be my choice and then floating pins can be retained.

[carlt5]

thanks
some useful info to consider
cheers