Jeff York wrote:
>>I'm adding a photo of the back side of one of the heads. They both
have a black carbon looking buildup outside of the combustion chamber
area. I should have checked the torque before pulling the heads. This
doesn't look normal. Is Permatex 3H suppose to be used on the matting
surfaces of the jug and the head ? <<
I don't use Permatex 3H anymore because it's messy and hard to clean up
on the next rebuild, but instead I use Elring Curil-T, a non-hardening
sealant that's used on metal to metal joints like case halves. It's a
favorite of Porsche engine builders and the like, and it works just
fine. I used that on the Corvair I'm building now (in progress for two
years, but on my short list for this winter). I use a small bead of 3M
"ultra" silicone sealant between cylinder bases and engine case, after
thorough de-greasing, of course.
You definitely run that thing way richer than I do. I run mine way lean
of peak unless I'm on climbout on a hot day. I'm a cheapskate, and not a
fan of lead deposits (I have to use 100LL because of what the fuel tank
is made out of).
I doubt that black stuff around the heads is blow-by....seems like
that would have torched out a path and you'd know about it. My guess is
that's fried oil, but I could be wrong. I've never seen one of my
engines do that, whatever it is. I do often use copper head gaskets on
VWs and Corvairs, especially if I'm tweaking combustion volume. They
squish a tad and ensure no leakage, not that I've ever had a problem
with that. CB Performance sells various sizes and thicknesses, named
"CopperHead" gaskets. I don't think any sealant in that joint would
last long, and would almost certainly squish out when torquing the heads.
I wrote the below earlier today, but hadn't sent it yet:
The link I sent this morning was Corvair oriented. I also documented
the 2180 engine I built for N891JF when I first bought it. It's very
sparse on explanation (I've only had 10 years to finish it up) but there
are a 125 pictures of the total rebuild process, including valve guide
replacement and that sort of thing. Hopefully you can get the gist of
it. CC'ing the chambers is over the top for an engine whose geometry is
already known and has been flying already, but this was a new build from
almost all new parts, which dictates attention to all details.
I guess I should spend the two hours to caption all the
photos.....maybe over winter. But first I should knock out the stuff on
my last list of "what I'll do during winter"..... two years ago. I
finally knocked out number one on that two year old list last week, so
no promises! See http://www.n56ml.com/n891jf/2180/ for excruciating
detail in the 2180cc photos.....
Mark Langford
m...@n56ml.com
http://www.n56ml.com
Huntsville, AL
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