"David R. Conrad" wrote:
>
> To all those who've been following the Pertronics performance investigation:
>
> Distributor "A" (points--all new components) now installed and running.
>Problem
> had been bad spade connector, at dist. for lead from coil (-).
>
> Timing set to 16 btdc; dwell to 53 degrees.
>
> Observations (subjective): Seems to run great; performance seems
>indistinguishable
> from Pertronics, dist, "B".
>
> Will perform timed "hill climb", at full throttle, on somewhat remote,
> little-traveled roadway near top of Hualalai. Will repeat test immediately,
>after
> installing dist. "B" (correct timing orientation, already determined).
>
> Should be fun and interesting--if not necessarily meaningful ;-).
>
> "David R. Conrad" wrote:
I am glad to see someone approaching this question with at least a
semblance of scientific theory. Most times guys simply start talking
about how good or bad they think such and such an ignition product or
idea is. Actually I guess that goes for most performance related auto
products and not just ignitions. Anyway that is a whole other story.
The conversion to a solid state or breakerless system of *any sort* will
not, in and of itself, improve performance on any car -- when compared
to a new, properly set, points system. What it will do is maintain that
"peak" performance over a long period of time, whereas the points will
require cleaning and/or regapping and/or replacing repeatedly during the
same time period. So the first and most obvious benefit is reduction in
maintenance costs and labor. But in addition, with a points system, you
will not notice the reduction in ignition system performance/efficiency
until it has advance to a fairly significant state, as the change is
very gradual. But your car's mileage and power output will begin to
suffer soon after the new points are installed even when you can not
feel the difference, and the situation will simply get worse and worse
until it becomes so noticeable or so much time goes by that you service
your points and restore the ignition system's efficiency. Then the whole
process will begin again. So a secondary benefit is that the ignition
system will not suffer a "wave pattern" in its efficiency. And there is
another benefit, which you have touched on in your testing, namely the
breakerless system's resistance to dwell changes caused by wear in the
distributor, and the concomitant increase in timing accuracy. This is
due to the basic design of a breakerless system and to the fact that the
breakerless system does not rely on the cam action of the distributor
shaft. Because of this it also means that your distributor will not wear
out, as it will with a points system that puts a side load on the shaft
due to the came action. While this is not what most folks think of as a
"performance" part, it does offer a significant increase in overall
performance, over a given period of time.
One last point (pardon the pun) is that breakerless systems need less
total advance than do points systems, so to get the best results, the
advance curve should be changed to best suit the type of triggering
system you are using (Electronic triggers work much faster than a
mechanical trigger can, so at higher speeds the points need more advance
to get the correct spark timing than a breakerless system does.)
The question of points or solid state will go on for ever I think,
without resolution. But consider this, no car maker currently uses
points, Chrysler started selling vehicles with breakerless ignitions in
1972, and no GM or Ford vehicle has had points since the late 70's.
There is a reason why the world's largest automakers went with solid
state triggering systems for their auto ignitions, and the same reason
lead all the other automakers to follow suit. It just flat works better
overall.
BTW David try this advance curve with your Pertronics system if you
feel like testing things any further.
18 BTDC static at idle (i.e. with no mechanical advance active at
all--timing should be the same with the engine idling or with it shut off)
Mechanical advance starts at idle rpm +300 rpm (i.e. car idles at 600
rpm then the mechanical begins to activate at 900 rpm)
14 degrees mechanical advance
mechanical advance is completed by 3500 rpm
This will give you a total advance (mechanical plus static) of 32
degrees at 3300 rpm. You can run this with or without vacuum advance.
To time this you should "power time" it which means you set the timing
as advanced as possible without causing detonation. To determine this,
you should do full throttle acceleration tests in top gear starting at
1500 rpm. Your timing is right when you can just *barely* hear any
detonation under these conditions but you do not hear any detonation
under normal driving conditions (if you consider full throttle in top
gear at 1500 rpm as normal you really ought to be driving a big V8 of
some sort :-). Once you've got the timing set right, check your static
timing (at idle). It should be between 16-20 but may range higher or
lower depending on your ear, the quality of your gas, and the condition
of your engine. If for some reason your static timing varies more than
+/- 2 degrees from 18 BTDC, you may want to adjust the amount of
mechanical advance (the amount, not when it starts or stops) to get back
to the 32 degree maximum (i.e. if your timing ends up set at 15 BTDC
then your total will be only 29 degrees and you may want to increase the
mechanical adv. from 14 degrees to 17 degrees. This curve will work
with points as well but you will need more total advance, say 34-36
degrees total, with probably a bit less static and a bit more
mechanical. Also the rpm at which the mechanical will start will have to
be a bit higher, say idle + 600 rpm and the rpm that it is finished by
will need to be a bit higher, say around 3800 rpm.
--
Marc Sayer
Editor/Publisher
Z Car & Classic Datsun Magazine
http://zcarmag.com
Voice 541-726-6001
Fax 541-746-0863/726-6001
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