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May 26, 2004
Brad,
my rebuilt 1275 smoked blue and I followed all sorts of advice from list
members to get it right before I finally fixed it.
Of many "cures" attemted, the two that made the most difference in my case
were:
1. Replacement of the rocker shaft. Too much oil was leaking out of the
rocker bushes. It was apparent by running the engine with the rocker cover
off. I left the cork gasket seated on the head and let the engine run at
fast tickover. It leaked so fast that it soon created a lake on the top of
the head as oil spilled out of the rocker bushes faster than it drained down
the push-rod holes. When removed, the case hardening had worn off the old
shaft. I put a "nearly new" one in and the oil flow reduced very
considerably.
2. My engine had unleaded valve guides fitted. I think the tollerance on
these allows oil to drain down the valve stems too fast. In my case I added
oil control rings to the EXHAUST valves as well as the inlets. This is the
one single action that eventually solved the smoking problem. In
engineering terms it goes against all logic as exhaust valves are only open
on the upward stroke of the pistons so they shouldn't draw in oil - but they
do. Or rather, they did on mine. Maybe my cam has too much "overlap" - I
don't know. This cure is not in the books, and it took me nearly 5000 miles
to get to this solution. 3 years and 25,000 miles later I have had no
further blue smoke problems.
In my case, the crank case breathing system was OK, but in many cases I
think this is also a major suspect area.
Guy
"Guy Weller" < Guy.Weller@... > 32329
Posted on May 26, 2004 11:12 PM
Posted to category(s) Carburetor | Cylinder Head | Drive Train | Engine (external) | Engine (internal) | Exhaust System | Exterior | Gauges | Intake System | Interior | Lubrication System | Restoration | Suspension & Steering | Technical Info | Tuning
