[T3] Update on engine problems and question about piston rings

["Mark Seaton" <mark.seaton2@ntlworld.com>]

<x-charset iso-8859-1>Hi  folks,
Hope you all have a very happy New Year!

Just a little update on my engine problems. You will recall that I was
getting nasty knocking noises while the engine was warming up and if I
pulled away hard. I checked the compression and found 1,2 & 4 OK at
120-130PSI, but 3 at 80. I was also having great difficulty getting the
carbs tuned and balanced. Well I didn't dare drive it any more so I pulled
my socks up and dropped the engine for a bit of investigation. Well it looks
like I'm luckier than I probably deserve. I was dreading a pulled stud,
burnt valve or cracked head. It seems that it was just that the head had
come loose-2 of the nuts on 3 were barely finger tight. I pulled the
cylinder to check the rings were OK and they looked fine. The bores of 3&4
seem hardly warn at all- you can still see the honing marks all the way up.
The only damage I can see is a little cutting/impact marking on the face of
no3 piston mirrored in no3 combustion chamber- looks like someone might have
dropped a washer or something in the inlet which wouldn't suprise me as
there was a 13mm socket wedged between the fins!! The damage seems only
superficial though and I am happy to just re-assemble and pray. I also found
that whoever assembled the engine last did not use cylinder gaskets and
there were no gaskets on the inlet manifolds- the manifold on 1&2 was loose-
you could wiggle the carb around (don't know why I didn't notice this
before). No wonder I couldn't tune the carbs properly. Incidentally, if
anyone needs a ring compressor I found that a "high-torque Jubilee" clip,
with the worm mech cut off and with short 3/16 ends bent out at 90 deg,
clamped with mole grips works really well- the only sort I could find to buy
at short notice were the long ratchet style which wouldn't have worked.

Anyway, my main reason for this post is that with the cylinders off I found
that the top compression ring (ATE) was not as decribed in my Haynes manual.
It has a groove running around it and this was filled with what looked like
carbon deposits. I tried to clean this out with a scalpel blade but it
seemed really well stuck- like it was supposed to be there. Then I started
to wonder if it was in fact meant to be there - a graphite implant to help
lubricate the top ring? Anyone have any ideas- should I clean it or leave
it?

I am really looking forward to putting the engine back in- what with a
properly tightened head, properly tuned and balanced carbs (with no air
leaks) and re-engineered heat exchangers (someone had welded on new bits of
tube to go into the silencer with 23mm bores instead of 29 like the tube it
was welded to- quite a restriction!) I think I will really notice the
difference!

Thanks for all the valuable info and keep on T3ing.

Mark Seaton
Orange and Rust, slowly getting tamed, '73 NonFI FB, London




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