Race Engine Forum UK

Hello,

I own a Fiat coupe 16v turbo. I just completed my first engine rebuild but I have a problem with the valvetrain. I fitted a tipo 16V inlet cam and it seems that the valve springs are bindings or the valve retainer is knocking when the engine is warm. Does anyone know this kind of issue with this engine head ? The cam lift is 10.1mm (standard is 8.6mm)

I would like to solve this without removing the head. Are there upgraded spring retainers available to solve this kind of problem please ?

Thanks in advance.

Jerome

Jerome, hi

it will not be the springs binding, they will take much more lift than that before they bind.

If the spring coils are all touching (they won't be in yours at that lift) you won't hear it and if they are binding (locked solid near full lift) the engine won't turn over at all. I cannot think of anything in the valve train that would cause that noise.

My guess is a valve (most likely inlet) is hitting a piston, but unfortunately a damaged big-end bearing sounds just like that too.

That sounds like a head-off job first, sorry.

GC

Thanks Guy.

The big end bearings are new and the noise is coming from the inlet camshaft and only happens at 2000+ rpm when engine is full warm.

I tried to rotate the inlet camshaft at TDC and it goes freely to about 20‚° further. So I guess that the valve/piston clearance is fine. I'm running wossner forged pistons also which helps having a good clearance with valves.

What do you think about the valve retainer center hitting the valve seal ?

No, I considered that, the retainer is well away from the guide.

GC

Thanks again

Worn bucket?