With all the tuning questions going on lately I thought I'd pass on a
little story of mine that I think everyone could learn from.
As many of you know I am from Ohio living in Colorado (from: sealevel,
to:~6000 feet). Well when I came out here I tuned the car up for the
altitude and then when I drove it home one summer, I discovered that the
plunger technique and my skill had attained a perfect sealevel tune when
done at ~6000ft. well regardless I left it alone for another year (read
car ran rich for 12months). one day while autocrossing I finished a run
and discovered the head gasket had said goodbye so I replaced it; while I
was in there I decided to clean the disgusting amount of carbon out of the
head. I did this but without removing the valves (read did not clean
valve seats). This was all fine and good until 12 months later...
...jump foreward to one month ago. one day, for no good reason i decided
I needed to tune my car up. When auto-xing I tuned it every month on the
day before the event, but for some reason I decided to tune it. all was
good except I was getting about 12mpg and the car wouldn't idle when it
was real hot (on the edge of boiling) so I decided to solve both problems
and lean the car, problem is according to the plunger method it was tuned
properly. well I decided I would lean the carbs (equally) until I noticed
the car try to die when pushing the plunger (indication of a lean
condition) well I lost track but I took about 8 flats out of each jet...
...jump foreward two weeks. the car is getting rediculously slow and I am
getting upset. I do a compression check and get 90,20,75,0 dry, and
110,30,90,10 wet (all with throttle closed - I know this is wrong) @#!% I
think to myself, I have fried my engine in about 15k miles. Well I start
poking my head around the engine and planning for a rebuild, when I notice
a dry spot on my engine. Said spot is on the back of the head on exhaust
side of rear head bolt, said spot looks baked dry. I decide to give my
car a full tune up before rebuild just in case. (I haven't done valves
since shortly after head gasket ordeal). Well as it were, none of the
valves had any clearance between stem and rocker arm, and the 2,4 exhaust
valves weren't even closing all the way.
Ultimately I determine that when I cleaned the 1/16 inch of carbon
out of chambers during head gasket change I left a ring of said thickness
on valve seats. After mixture adjustment the carbon started getting
burned off of valve seat, so the valves could close on seat, thus reducing
clearance on rocker. Currently the car drives very well and gets 26mpg
city. The moral of the story is that I should have tuned the car
correctly in the first place, but also that simple things have a strange
way of causing problems that look really bad.
When something happens, don't neglect a full tune-up, you may find
something strange. BTW the dry spot on the head was from the exhaust gas
on non-closing valves blowing out the valve cover gasket and cooking the
oil dry. This has since gone away. So the engine is now evenly coated in
dirt and oil.
Well if you made it this far, thank you, hopefully everyone gets a laugh
at this or maybe an idea about something on their car. I thought it was
an interesting story, and I felt the need to tell it to someone.
James Nazarian
'71 B roadster
'71 BGT ever so slowly turning into a V8
'63 Buick 215
"I am temporarily out of witty quotes" -James Nazarian
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