SOS from Italy: UPDATE

[alexbert]

So, I removed all the head nuts: unfortunately i had three studs off. It seems no material (aluminium) came out with the stud thread. Actually they turned very (too much ...) easily, so there was no chance at all. When I have the cylinder off I will check better status of their holes/thread in the block
For the other ones I had to use chisel and a small saw... some small damages occurred...
Any way: I will post some pics to have your suggestion about holding or replacing.
A question: the lower stud rows are the rocker arm ones.
Their nuts are completely loose: is that normal? when I will replace the head and these nuts, how much do I have to tight them?
maybe I need a little bit more explanation how it works here ...

Alex

[azdave]

I think you are asking how far do you tighten the nuts on the rocker arms to adjust the valves after re-assembly. They can be adjusted with engine running or not based upon your preference. The factory manual describes the process. It is not difficult.

Also good info to read here.
http://corvaircenter.com/phorum/read.ph ... msg-296743

[bbodie52]

I would not worry too much about few loose studs. When I rebuilt my first Corvair engine in 1969 I remember several upper and lower studs unscrewing, and a couple more that had to be cut with a hacksaw blade because the head nuts had rusted and softened over the years and I was unable to successfully chisel them off. But as long as the aluminum threads in the cases are intact, Clark's sells replacement studs with slightly oversized threads that will allow you to reinsert the studs with an appropriately tight fit. If the threads ever do actually get damaged or strip out, Clark's offers repair kits that install steel inserts in the cases to properly anchor the studs, in a repair procedure similar to that used in the cylinder heads when a spark plug hole strips.

Whe you reinstall the heads, you will need a gasket kit to replace all of the old rubber O rings, valve cover gaskets, and cylinder head gaskets. Torque the head nuts and rocker arm studs using the head nut tightening sequence shown in the shop manual, using the torque specification stated in the shop manual. (Don't forget to reinstall the push rod tubes and new O-Ring son those tubes, an new O-Rings on the rocker studs. If you removed the cylinder barrels, be sure to reinstall the sheet metal air deflector under the cylinder barrels before inserting the push rod tubes. If you forget these things you will be forced to dismantle and reinstall to get everything into place. (You would be amazed how many people reassemble an engine while leaving pieces out, only to discover later that they have parts left over.

It is good idea to NOT reuse the old upper head nuts. The metal becomes soft and rusty, and it is better to install a new set of nuts, and possibly the stud thread protector cap nuts as well that are offered by Clark's Corvair Parts. I recommend you read over the material shown on the three Clark's Corvair Parts catlog pages below. You should find it very informative.

http://www.corvair.com/user-cgi/catalog ... N&page=173


http://www.corvair.com/user-cgi/catalog ... IN&page=13


http://www.corvair.com/user-cgi/catalog ... ge=OTTO-12