Proper Cam Tower/Head Installation 65-89

[conrad_bookout]

Hello!

According to the 1972 Porsche Workshop Manual, the correct procedure for affixing the heads and cam towers is to attach the heads to the cam towers using Loctite 573, then attach the combined head/cam tower assembly to the cylinders. According to this manual, the torque for the cam tower nuts is 25 Nm and the torque for the heads is 33 Nm.

However, according to the 1984 edition of the Porsche Workshop Manual, the correct procedure for affixing the heads and cam towers is to torque the heads to 15 Nm plus 1/4 turn (!), then attach the cam towers to the heads using Loctite 574 torqued to 25 Nm.

In the excellent Porsche rebuild book covering years 1965-1989, yet another procedure is proposed which is to partially tighten the heads, attach the cam towers using Loctite 574, then fully torque the heads. According to Wayne's book, the cam tower nuts should be torqued to 25 Nm and the heads should be torqued to 32 Nm.

So, and I'm sure you already guessed it, what method is currently in vogue of putting the heads/cam towers on a 65-89 Porsche 911 (mine is a 77)? Does it really matter which method one uses? Is one way more or less prone to leaks?

And why do the newer, higher compression engines require less torque to hold the heads down than the older lower compression ones.

Thank you and keep up the good work! Without Pelican, I'd be lost....

conrad

[cgarr]

The heads have to be torqued last no matter what order you stack them, I set the heads and cam tower first, then its one unit ready to install. I have no idea how you could install the cam towers after the heads are torqued in place, there is no alignment without the tower.

[john walker's workshop]

assemble the heads, towers, cams and rockers first, then plug on the complete unit. way easier that way. others will disagree as usual.