----- Original Message -----
From: "Bob Tom" <tigers@bserv.com>
To: <dakota-truck@buffnet.net>
Sent: Tuesday, March 13, 2001 5:11 PM
Subject: Re: DML: New Spark Plugs
Well once again you have been a big help to me. Thank you. After reading
your note a few times I figured that the best for me would be the autolite
5224. The reason being that I'm not into racing or hot roding just
efficiency and longevity. In addition you mentioned that colder plugs tend
to foul up quicker with normal street driving, also I have not noticed any
pinging at this point and there is 55-56k miles on the engine. This of
course could change in the future, at which time I could, based on your
info, modify my plug requirements. My driving RPMs do stay around 2000-3500
with occasional high ends at 4200 for passing in a hurry. So in closing I
will go with the 5224's and again thank you for the info.
> The Champion RC9YC4s, which are equivalent to the Autolite 3923s, are
designed
> with a bit thinner and shorter center. This design is what the
> manufacturers came
> up with as a best compromise in driveablility/wear/economy for cars. The
books
> will list these plugs for the 5.9L magnum or LA 360 engine but does not
mean
> that they will not be fit for the 5.2L magnum or LA 318 engines.
>
> The Champion RC12LC4s, which are equivalent to the Autolite 5224s, are
> truck plugs with their thicker and longer centers. This is what the
> manufacturers
> came up for pickup trucks as a best compromise for plenty of low end
torque and
> for drivlng mostly of in the 2500-3000 rpm range.
>
> The 3923s are one range colder plugs while the 3924s are the normal heat
range
> plugs. Colder plugs are used if the engine is pinging a bit in hopes of
> eliminating
> the pinging because colder range plugs will dissipate heat away from the
> combustion
> chamber quicker. Colder plugs will also tend to foul up more/quicker with
> normal street
> driving.
>
> Why you see the 3923s mentioned so much on the list is because they
produced
> a bit more rear wheel horsepower and torque (dynoed by DMLer Jon Smith) on
the
> 5.2L and a number of DMLers were experiencing pinging in their engines. I
> don't
> know what Autolite does in their design/manufacturing process but they
> contininued their reputation for putting out performance plugs which began
> with the muscle cars of the 60s.
>
> General experience on the list (mine included) is that the Autolites
produce
> a little smoother idle and wear longer than the Champions. They are also
> not very expensive.
>
> While different manufacturers list equivalent part numbers for plugs, this
does
> not mean that they perform equally for a particular engine.
>
> First you need to decide if you want a truck plug or a car plug. Then you
need
> to decide which manufacturer, and, finally, what heat range. If my
driving
> needs
> matched your driving needs (and assuming your engine does not ping), I
would go
> with the Autolite 5224s gapped at the recommended 0.040", having
experienced
> how my truck ran and how the plugs wore during the first year with the
stock
> Champions. Notice that this is a 'truck' plug with the normal heat range
...
> the only difference being brand selection.
>
> Personal 63 years opinion/experience: If you're searching for perfection,
> you'll never
> find it.
>
> Hope this helps.
> Bob
>
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