Quoting W Bell <cbody67tx@xxxxxxxxxxxxx>:
> What he DID talk about (which I suspect dealt with his current products) was
> about misfire in engines as a matter of course. That every cylinder did not
> fire off completely or at all during every revolution. He mentioned that if
> the "computer" sensed that a "fire" did not take place, it would immediately
> "strike" that cylinder again. He also talked about doing some research for
> the auto manufacturers in that area too. That might be the secret to why you
> saw the gains you did?
How can the computer "sense" that the engine missed? And even more unlikely,
can the computer be fast enough to charge the coil and fire again within the
cycle? One possibility of the improved mileage on these truck cases with the
Jacobs ignition is that the new ignition had better suited advance curves for
these small cam engines. Or even more likely, the previous point igntition had
problematic vacum or centrifugal advance units.
>
> The misfires he talked about might be more correctly termed "marginal fires"
> than full misfires as such, possibly.
It turns out that there is no marginal fire. The mixture either ignites or it
doesn't. There can be a cycle to cycle variation caused by variations in the
ignition process (which is one of the reasons and engine may run rough even
though there is no missfire) but by about 60 degrees past TDC, pretty much all
the fuel is consumed (unless there is a missfire, in which case all the fuel
will remain unburnt). The roughness is caused by variations in the pressure
vs. crankangle due to the differences in the way the flame propagates and the
rate of combustion. This typically happens at lower rpm's, as at higher rpm
the turbulence ensures quick flame propagation, which is less sensitive to the
ignition process.
D^2
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