Fiat 131 TC 8v to Tipo 8v piston interchangeability

[sumplug]

Hi Guy.
Can early new 84.4mm[131 1995cc upto 1985] be used on a later reverse head 2.0 litre 8V engine from a Tipo?
This will solve an argument, thanks.

Andy.

[Guy Croft]

well, Andy

The Fiat 131 2 liter TC 8v piston has compression height 38.45mm, the 8v Tipo is 39.80mm so for a start the 131 TC piston would sit 1.4mm or so low in the Tipo bore. Yes the Tipo piston has a small bowl in the crown 1.6 mm deep, but the effect on CR would be quite marked from the lower piston.

The 131 piston has two valve reliefs, one for inlet and one for ex, the Tipo needs 2 vrs as well but because the engine is reversed port the 131 piston vrs are the wrong way round in effect. The 131 piston ex vrs would need machining bigger diameter and maybe deeper.

Both pistons have pin offsets so the 131 piston must go into the Tipo engine with same orientation as original engine, ie: old 131 inlet vr would go on the Tipo's ex side. Big for that side but it doen't matter.

I am not sure if 8v Tipo engines have internal oil sprays to the piston undersides, and whether the Tipo pistons have a slot in the skirt to accomodate it, sorry, do not have any here to look at. I would definitely not modify a 131 cast piston skirt if that was the case. Apart from the latter issue, they'd probably go I guess, unless I've got my numbers all wrong...

Hope that helps.

GC

[sumplug]

Hi Guy.
Brilliant, thanks.

Andy.