Gudgeon pin knock?

[Guy Croft]

RULE:

There is a harsh lesson here.

If you want OE quality buy ONLY from OE dealer with a Fiat or Lancia sign over the front door!

Nick - first they told you they would 'bed in' and now you're wondering if they weren't honed properly. I'll tell you: these rods were not OE production line items.

Readers be aware: There are all sorts of 'passed-off' parts on the market, pumps, rods, cranks, and that's just standard parts. When it comes ot raceparts it goes way deeper.
Regardless of any undertakings made in respect of their 'fit for duty' do not buy them. Unless using race proven substitutes from a reputable source and of completely traceable origin use genuine Fiat , from a Fiat dealer ordered by part number.

You will readily understand that I say these things in the general interest.

GC

[NickRP]

Well, I had to learn this lesson the hard way :(.

Thanks GC, thanks Andy,
Nikola

[NickRP]

Just looking into workshop manual how tight the clearances for the piston pin/rod bush are... It might well be that I got set of rods with class 1 bore and piston pins of class 2.

It is very hard to assess tightness of fit by the (human felt) force needed to push the pin through the bush... but it was like 0 on 0 type of fit (i.e. no clearance, but also no tight fit). Still, I could slide the rod axially with no markable effort (between the piston pin bosses), so I thought it was ok.

In which class are OE items delivered? I could run into same problem if class 1 and class 2 are randomly supplied.

Regards,
Nikola

[Guy Croft]

The setup is size classed (OE specs):

Piston pins
Grade 1 21.991-21.994
Grade 2 21.994-21.997

Small-end bores (bushed)
Grade 1 22.004-22.007
Grade 2 22.007-22.010

So you can see that irrespective of the small end bush grade the pins would always be a sliding fit by with at least 0.007mm. The factory designated fit is 0.010-0.016mm (5/10thou")

GC