Fiat TC 8v camshaft end float

[Uros Piperski]

Hi guys,
What is the minimum and maximum allowed camshaft end float on the TC? I have 0.22mm and I think it's too much. I'll make a thinner gasket, but how thin should I go - what is the minimum endfloat?

Thanks,
Uros

[Guy Croft]

As a general rule end float, be it on crankshaft or camshaft or any other rotating item should be sufficient to permit ingress of enough oil (under pressure or by drip/splash) to develop a protective film.

That means min clearance of around 0.08mm (2thou"). On cranks a maximum of 0.30mm (12 thou") is generally permissible but naturally the crank is subjected to an applied (and heavy) end load from the clutch and to stop it 'banging around' (crude but apt description) and impacting on the rear thrust washer I usually reduce to about 6 thou" in the cases where it's a bit 'loose'. With a wide clearance of course the oil leaks away more readily and you really do rely on those thrust washers being well lubricated..

As far as camshafts are concerned there usually isn't any externally applied end load and the to-fro movement of the cam in your case is only generated by the action of the cam lobes on the buckets and is - compared with the crank) - pretty modest. I don't have any 8v OE cam end float data (not sure it was ever published) but it's going to be the same as the 16v which is quoted as 0.08-0.23mm (3-9 thou"). So this means yours is 'in limit'. I can tell you I have seen them much looser than that and it doesn't matter any. It is of course essential to rotate the cam in its housing after fitting the gasket and end cap, because if it's tight, you are going to cause severe overheating and damage in an area of the engine that is impossible to get to in-situ. That is the golden rule of rotating things - they must always spin freely.

Some photos below, hopefully self-explanatory.

As a rule - avoid the use of abrasive paper when dressing alloy mating parts that are in rotating or sliding contact, you can embed abrasive particles in the soft alloy. A fine carborundun stone (in good flat condition) is the best way to 'dress' high spots on the end plate and assure flatness (because there is oil film between the parts you don't need to try and achieve Olympian standards of flatness, not like machining a head face..) and then rub the parts with fine Scotchbrite to develop the minute scratches that are so good for oil retention. You can use the same technique on seal housings, camboxes and mating faces cambox to head, oil pump mating faces, crank to flywheel and many other areas too. It is good, diligent engine building practice.



GC

[Uros Piperski]

Thanks Guy, for a very detailed anwser with a lot of tips.