Sensor Question (and the usefulness of cam sensors)

[Bruce]

From: "clayb" <clayb at sbcglobal.net>
Subject: Re: Sensor Question (and the usefulness of cam sensors)
> > From: "Bruce" <nacelp at bright.net>
> > > That said, I've found that cam triggering of ignition is definitely
> > > inferior, especially when a timing chain is involved. With a
distributor
> > > firing my turbo 454, timing would bounce at least 5 degrees, while the
> > > distributorless ignition stays rock steady.
> > > There can be no doubt this has an impact on my ability to tune near
the
> > > edge of detonation.
> > At idle it would wonder that much?, or thru out the rpm range.
> > How big of cam?.
> > Bruce

> It wasn't always that bad at idle, but it did wander noticeably. Seemed
> the worst timing accuracy was when the engine ran at constant speed,
> like 2000 or 3000 rpm. Any slack in the system is then noticeable. Under
> smooth acceleration, the chain and gear are preloaded in one direction.
> Cam is 241/234 degrees.
> - Clay

That much cam (that is at .050", right?), is going to need a whole lot of
valve spring, and yes there is a terrific load on the timing chain.
The other thing is with the CAM also wondering that much, even if you got
the timing rock steady with say a crank sensor'd set up you'd still be in a
*hurt* cam timing wise.
It might be an easy diagnostic aid to keep the distributor, and from time
to time put a light on it to see if the timing is getting erratic, and then
you'd know that the chain, gears etc are dead.
Just thinking out loud
Bruce


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