Advice re piston for ‘55 G3LS

[g80csp11]

The gudgeon pin ( wrist pin) should always be a sliding fit into the small end bush . ideally lightly oiled the pin would fall slowly under its own weight if the rod was out of the engine . New bushes will always require reaming when fitted as they are a interference fit in the conrod . if the clearance is too tight it will seize on the pin .

The clearance of the pin to piston is manufacture dependent, sometime requiring warming of piston to get the pin to go in . may only need hot rag !

[G3L1946]

Thank you Peter , appreciate your input.
Regards,

Steve

[Andy G]

ideally lightly oiled the pin would fall slowly under its own weight if the rod was out of the engine .

You may well be correct, but I always thought it was the piston crown itself that is described as "falls under own weight " when fitted to rod, rather than the gudgeon pin in the rod without piston.
If pin drops in under its own weight it might be a touch loose?

[Joker_Bones]

I used an original pin. I do not offer that as a recommendation as logic and the numbers will tell you the pin to piston will be too loose a fit.

[Expat]

Thanks for the update Russell. I’m now thinking I may get an adjustable reamer and take a dust cut so the new pin enters freely. Don’t have one of that size in my tool collection used when at work.

[Joker_Bones]

I didn't have a suitable reamer either... but imagine it would be the best course of action if the new pin is too tight in the little end bush.

[Expat]

I did heat the small end with hot air gun to see if the pin would enter though didn’t freeze it. If I had, it may have gone in but then would have been stuck so not a good idea!

[g80csp11]

it really must go in with components at the same temperature
I would set clearance between 0005" to .0012"or a sliding fit as previously mention , otherwise it will seize on small end , and then on the bore

[Expat]

Got the adjustable reamer today and made several passes through the small end bush, adjusting it bit by bit until the new pin slid in nicely. Pleased with progress so far. Next, check ring gaps then fit piston, new circlips and rings then cylinder.