<VV> Leak free valve cover installation

[Sethracer at aol.com]

A member writes:

You said earlier that you had used drilled and wired nuts on studs to  secure 
your valve covers and had had no leaks.  I'm intrigued by the no  leak part.  
I'm only familiar with what I've seen on aircraft.  If  you get a chance in 
the next few months I'd appreciate seeing a photo of how  you did it.  
 
Thanks,   Bob -   "never too many projects for my  Corvairs"





Bob - I will try to describe it first.  I will try to shoot a couple  of 
photos for you when I can.
 
If you are using original stock valve covers, the first thing I do is glue  
the new gasket into the cover. You can use any regular silicone gasket sealer 
to  do that, but I use regular Yellow - Gorrila snot - Also available in Black 
-  That is 3M Super weather-strip adhesive. I clean the contact face on the 
valve  cover with lacquer thinner. Really clean! I pre-position the gasket - I 
prefer  the composite cork and neoprene gaskets from Corvair Underground, but 
others are  okay. The Composite ones are tough. You can tie them in a knot and 
they won't  rip. I clean the gasket surface off with lacquer thinner as well, 
and trial fit  them onto the covers. Make sure the slots for the alignment 
tabs are okay, and  the holes line up as well. Then run a thin bead around the 
face of the cover (I  smear it to get good coverage) and carefully align the 
gasket and press it  down. If the gasket is thick enough for the head-contact 
face to protrude out  past the edges of the valve cover, the next thing you do is 
place the valve  cover face-down on a very flat surface. After you have both 
in place, next to  each other, but not touching
 
Note - If, for some reason the new gasket does not protrude out past the  
edge of the valve cover, then take another gasket and place it on the flat  
surface first, then set the valve cover down, aligned on this second gasket. 
 
Pile a few large books on top of these valve covers to lightly press the  
valve covers onto the gaskets, gluing them in place. Let them sit  overnight. 
 
Buy a 24" piece of 1/4" x 20 threaded rod (galvanized is  good) from the 
hardware store, you will need to cut off eight pieces.  The length that works for 
me is 1.75"- But I am using aftermarket valve covers  with thicker flanges 
where the studs protrude. With stock covers and  spreaders 1.5" length is 
probably better. Four or five threads for the  final nut installation is plenty. The 
method I use for cutting usable  pieces is to thread on eight good 1/4-20 
nuts, six of them to about the  middle of the 24" rod, the seventh and eight 
should bracket your first 1.5" cut.  clamp the second to end nut in a vise to hold 
the rod and cut off the first  piece with a hacksaw. When you cut through, you 
will have a pair of mangled  end threads. Use a grinding wheel to smooth out 
the aread around the  parting, and use the installed nut screwing it off the 
end to make sure the  threads are okay - Purist can use a 1/4-20 die for this, 
but a nut works fine.  Clean up the cut on the long rod in the same way, and 
repeat seven times. The  extra nuts on the long rod are just for convenience, 
you could use the same nuts  for all cuts. Just remember not to cut unless you 
have a nut already on the long  rod to reform those threads. It's a long way 
from the otherend!
 
While you are at the hardware store picking up the threaded rod, buy ten  
"tall" 1/4-20 nuts. The ones I have are about 7/8" tall and 3/8" hex.   Before 
you go further, you will cross drill the nuts about 1/8 to 3/16 in from  one 
end. I used a . 073" drill (from a numbers/letters drill bit set, I don't  
remember the callout). I clamped the nut down in a vise and drilled through  at the 
proper angle. When you break through the first side, be very careful  about 
engaging the threads on the other side to drill out. It is easy to break a  tiny 
drill bit doing this. Clean up the holes in the cross drill, to  prevent 
blood letting in the future.
 
Installation - You should clean out the holes in the heads first. Some  spray 
cleaners will instantly deposit all the crap into your face or  clothing if 
you just insert the tube to the bottom and spray. Use a rag around  the tube to 
catch stuff. Investigate to be sure the threads are clean. While you  are 
cleaning, clean off the contact face of the head as well. Double nut and  screw 
the cut inserts into place - all the way to the bottom of the holes.  A light 
tightening with a wrench is fine. Don't overtorque, especially  with old 
partially screwed up threads. (Or it will be "insert"  time).
 
Final assembly. I clean off the face of the valve cover gasket, cemented in  
place as above, and recheck the alignment of the holes. It is important  
because you will be inserting all four studs through the holes at one  time. You 
can trim the inside of the gasket holes a bit with an exacto knife if  needed. I 
grease the contact face of the gasket before installation. Oil is  probably 
fine, I use Moly assembly lube, because about 25 years ago I bought a  100 year 
supply! make sure you have good even coverage but not a lot extra.  

Slide the valve cover on carefully. All holes will have to be aligned for  
this to go smoothly. Bottom the cover onto the head. If you are using clamping  
spreaders - slide them over the studs at this point. Install the eight  
cross-drilled nuts now - the hole-drilled ends out, please -- and torque them to  
your proper clamping force. With stock covers and spreaders, I tighten the nuts  
down until my fingernail will just fit between the spreader and the valve 
cover  at the hole.  (That is the same torque value I use on stock cover bolts as 
 well). The end of the stud should be well down in the threads of the nut.  
allowing passage of the wire.
 
Now to the wiring of the nuts (did I take the long way around?) You don't  
need to safety wire the nuts as you would a torque specific fastener on an  
aircraft. (or the trans to diff bolts on a racing Corvair!) All you want to  do is 
prevent the nut from backing off -- then falling off. I believe that a  
half-turn in either direction won't matter much. I simply align the nuts so the  
holes are longitudinal, slide the safety wire though both holes on one side,  
across the top of the cover vertically and through the other two holes, then  
spin the wire together to retain them. In a real torque  sensitive application, 
you are supposed to use the direction of the locking  connection to pull 
torque in the correct direction of the threads. My favorite  description of the 
proper methods is in "Prepare to Win" by Carroll Smith.  I am sure it is also in 
various aircraft manuals. 
 
My final note - I have used the above method on various Corvair race cars  
for about -- well, a long time. And I have never had a valve cover  leak. Given 
the "reputation" of the Corvair as a leaker, I choose not  to add to that 
reputation.  Although specifically applicable to racing  Corvair engines, it could 
easily be applied to a street-driven Corvair as well.  Any questions, just 
drop me a note.
 
 
 
Seth  Emerson

C's the Day! - Corvair, Camaro, Corvette



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