Technical piston arrow and rod orientation

[shambolina]

im in the middle of building my 1108 fire engine. its been completely stripped and the engine shop isnt sure which way the piston arrow should face in relation to the rod and the block. Can anyone advise or show pics of them being installed in their build? Thanks

 

[portland_bill]

Good grief, really? The engine shop do not know which way to point the arrow?
An arrow on the piston will normally point to the front of the engine. This is where the timing belt is, not towards the front of the car as the engine is fitted.
On older engines, and I'm talking a very long time ago, the arrow might face towards the thrust side of the piston. But as that requires a little thought, it was not used much, and unlikely after the 1950's.

A quote from eLearn the genuine Fiat manual:
"Make sure that the arrow, stamped on the piston crown, is facing the timing side and that the number, stamped on the big end, corresponds to the one of the connecting rod cap."

 

[shambolina]

Thanks for the reply. They did think that's the way the arrow should face. They are also questioning which way round the rod should go in relation to the piston. E.g. if I was looking down on the piston arrow, where would the numbers on the rod be?

 

[portland_bill]

eLearn does not mention a particular fitment for the rod, so hopefully it is symmetrical. If careful examination does not identify any offset, which I doubt it will, then I'd put the numbers towards the front (timing belt), just for consistency.

As these engines are built by robots, it is likely the rods are symmetrical.

 

[shambolina]

Thanks Bill. I appreciate you taking the Tim to teply