16V head problems?

[Neil Roshier]

I'm in the market for some 16V heads for race cars, however I've heard different reports of heads warping and breaking cams and high wear rates with the valves?
Would anyone have any insight into these 'problems' and if they are true.
Many thanks Neil

[Kevin Braithwaite]

I'm researching the same thing as yourself for the same reason(I want 16v race ingine in my beta)
I read last week that the major problem with early 16v heads is insufficient clearance between the valves and their guides.I believe the problem was rectified with late model themas and integrales. I expect engine no's will be relevant here. I think iI read this in Guy Croft's great book on Fiat twincams,but I'm not too sure. I'll research then get back to you.

[Neil]

thanks for the replys, the info that I have so far is that the hardening on the early cams is not up to scratch and can be rectified. Cheapest place for regrinds or billet cams is Tighe in australia who will weld on new metal to grind and thus keep the original base circle. cost is around $450-500 australian and 700-800 for billet which is cheap when compared to others.
Other info points to cracking between the ex valve and the sparkplug and some warping. Also watch out for the threads in the cam caps as they can strip and are hard to repair.
Would be more than happy to share any other info is required and hear any new info/opinions.

[Ville Vieri]

You are right, that valve stem clearance problem was mentioned on the Croft book. But which of the heads are early type? I have a head of Thema 16v ie -89. Is this early or late head? Do I have to ream or replace the valve guides? However, it does not have any sign of excessive wear in camshafts or valve guides.

I am going to use that head with the Fiat 131 bottom-end.