> The latest theory is timing.<
Mike,
I bet on the timing, I suspect it is too advanced. There are all sorts of
theories as to where or how you should set it, but here's my opinion.
If infact you find it appears to be advanced just retard it and road test.
Continue this procedure until the ping goes away. I have found that this will
provide the timing that gives the best performance.
Larry
1969 MGB
Denver Co
===========================Mike writes=======================
> Thanks for the reply. Now the TF mystery,.
>
> For over a year the TF has a strange problem. After redoing the head ( I had a
> burned valve and wanted a lead free head) the engine would break up on long
> straight runs of 4000 rpm when you increased the gas to make slight rises in
the
> road. The car pulls up mountains at any rpm even 4500 for long periods without
> problems. The break up only occurs on relatively straight runs with a steady
gas
> pedal followed by a slight increase to make the slight hill. What happens is a
> suuden loss of power and a chainy pinging noise. If you push in the clutch and
> let the rpms drop to idle, then release the clutch the car recovers with full
> power. The engine never dies when this happens, and if you push on( without
> letting the rpms drop), the pinging continues .
>
> I have rebuilt the carbs, changed the floats, replaced the seat and needles,
> changed the plugs , points, rotor, cap, condenser, and coil.
>
> Most believe it is fuel starvation, and I have changed fuel pumps and cleaned
> all screens and filters including the tank screen.
>
> The latest theory is timing. Although the car starts well, and runs great, the
> theory is that I am near the edge of advance or retard, and the extra advance
> with a hot engine at high rpm pushes the timing to the edge and I get pre
> detonation. Another theory relates to the head replacement. This is that a
fine
> ring was left on the bores of the head when it was machined. This fine ring
> heats up on steady runs of 4000 rpms and glows, thereby detonating the gas
> before the spark. Aparently the machine shop should have sanded the edge of
the
> bores lightly after planing the head.
>
> The whole thing is wierd . I can avoid the problem by varying the gas pedal
when
> I reach the small hills, pressing down and letting up on the gas as I climb.
As
> long as I don't keep a steady increase of pressure I avoid the problem, but it
> is a pain to remember to do this.
>
> I plan to redo the timing Monday and then wait for good weather to see if this
> works. If it doesn't ,off comes the head. I hope I can avoid that. Taking the
> head off means new gaskets and a look into the engine. I always hate to see
> what other problems are lurking in there.
>
> I would appreciate any comments.
>
> Mike Leckstein
>
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