Xflow rods and gudgeon pins

[mexicotait]

Hi folks

Im replacing the pistons in my crossflow and reusing the original rods.

However when put a piston on a rod the pin is too tight a fit on the rod so the piston is hard to move

Can i polish the pin so that the rod isnt such a tight fit?

[Graham]

did you oil the pin/piston?

just warm the piston up slightly and the pin should move freely, if it does its fine

[Pushrod King]

Have the little ends been re-bushed? If so they will need to be reamed to size. Also which make pistons and pins are you using? I've experienced slightly oversized pins being supplied with some forged pistons.

[mexicotait]

Just using ae cast pistons
The rods were used in my engine with standars ford pistons
The pins will push through the piston fine but the rod binds
They havent been rebushed

[HonkyWhiteTrash]

If you need to polish the pins by for example 0.001" then that makes the pin a looser fit in the piston by 0.001". Really you need to be doing some measuring and working out if things will be in tolerance. It's a quick job. Once you've got the info you can work out whether it's suitable to do so or whether you need to ream the rod bush which is likely to be the best approach based on what you've said.
However, I would be checking that the rod bush hasn't been damaged when the pins were pressed in - they can damage easily if slightly out of alignment when pressing/tapping them in.

[Graham]

often the case until you wriggle the piston about on the rod a bit. did you oil the pin/piston/rod?

how tight?, if it just a bit stiff but frees with a small amount of heat on the piston it will be fine.

[mexicotait]

Was just stiff
Left the pistons on top of the boiler
Pushed them all together easily and they are nice and free now
Cheers graham

[racing escort]

The rod needs to be dead in the middle of the piston also ...