turbo lower valve covers on 67S

[ajwans]

Is this an important swap on an aluminium 67S case
with aluminium valve covers?

I don't want a leaky engine when I put it all back together
so if there's a risk it will leak I'll get the machinist to add
studs for the 11 hole cover.

andy

[304065]

Well, it was important enough for the factory to make the change.

That said, on my own '66 rebuild I am not going to later covers for originality reasons-- I have had the cam towers and the covers lapped flat, the studs changed out for new ones and will use silicone gaskets to try to keep everything from warping.

Modern cam boxes are cheap, you might save money by buying a used set vs. having the old ones modified.

[docrodg]

The magnesium covers are the ones most known to warp. You can always plate-glass sand yours lightly to ensure they are flat.

[Flat6pac]

I would go for the orginality, the stuff is aluminum so there isnt a warp like the magnesium. If you must, buy cam carriers, everyone has extras.
Bruce

[Henry Schmidt]

The most important reason to swap out the early cam towers is the spray bar. In 67 (the first year of the spray bar) there are only two oiling holes per head. The factory felt a third oiling hole made sense so from 68 on they added both extra valve cover studs and one more hole per cylinder.
We use the later version of the 47 mm cam tower on all early engines. If originality is important (quite often it is paramount) we remove the additional studs (5) and fill the holes with a plug. Oddly enough the spray bar plug (available from Porsche) works great as a filler (plug) for this application. Looks original but offers extra oiling for better lubrication and cooling.
On early race engines we go one step further and use the 47mm 4 journal cam tower with 4 journal cams. This adds rigidity to the cam at in high RPM. The best source for 47 mm 4 journal cam towers is the 77 2.7 911. The casting was changed for the up coming 49mm cam journal (78 and late) and the 4th journal is there but no hole is drilled for oiling that journal. You simply drill and plug that one journal and you're good to go.

[304065]

Originally Posted by Henry Schmidt

The most important reason to swap out the early cam towers is the spray bar. In 67 (the first year of the spray bar) there are only two oiling holes per head. The factory felt a third oiling hole made sense so from 68 on they added both extra valve cover studs and one more hole per cylinder.

Henry, good point. One minor correction, the first spraybar engine is 903070, which is a late 1965 calendar year change during the 1966 model year. The original holes are as follows:

In the camshaft housings are aluminum tubes with holes, three of which are approximately 3 mm (0.12 in.) dia. through which the oil flows to the camshaft bearings. Six holes of approximately 1 mm (0. 04 in.) dia. , splash oil on the cam lobes. The remaining three holes allow oil to splash against the inlet valve cover in such a manner that it will drip down on the rocker arm and valve stems.

[ajwans]

I already have the spraybars out for cleaning, is there a source for the later
style spray bars with the extra holes?

andy