TSB#9404 946 Head Height
 

Hi All

If I understand it correctly, this TSB addresses the head/cylinder leak on the early 964's. Where can I find this TSB? Does the head height indicated in the shop manuals of 84.48+/-0.02mm change after the heads are machined as per the TSB. The manual limits head resurfaces to 2 of 0.1+/-0.02mm each, which would give a minimum limit of 84.28mm {i.e. 84.48 - (2 X 0.1) } - am I interpreting this correctly?

Thanx in advance
Bill
90C2

Specifications can be found in Porsche Carrera 964 Technical Data Without Guesswork, Bentley Publishers, 15-4, cylinder head machining.

I don't have the book handy, or I would give you the specs.

Porshaah,
The number you posted, 84.48 +/- 0.02mm refers to the dimension and tolerance of a NEW head.

According to the Bentley Technical Manual:
"The maximum metal (quoting now) that can be removed from a cylinder head (groups of three) is 0.20 +/-0.02mm".

So your first machining attempt would be 0.10 +/- 0.01mm (0.004"). The second attempt would be the same and then you would be at the limit.

Good Luck,
Mark

Bill.
Send me your email and I'll send you the TSB