I have read a couple of tech articles on the design philosphy behind project
nose plugs. The idea for using the projected nose is it's further into the
chamber so the incoming charge will cool the tip allowing a higher heat range
to burn off deposits.
Now the 5224 and 3924 are both projected nose plugs (the 5225 is just porjected
more) and why DC chose to change the recomend plug from 3924 to 5224 in 97 is
anyone's guess. Could have been for emissions or economy or they may have found
the engines run better.
If you have a detonation problem going to the cooler 3923 plug may help (there
is no 5223).
The magnum head design is a closed chamber quench design. This design is
supposed to create a lot of turbulance in the chamber that makes the engine
less suceptable to detonation. However the piston and the head have to come
very close to each other (0.040" is considered about perfect) for this to work,
the magnum engines as delivered from the factory have the piston about 0.050"
down in the cylinder so the gap is on the order of 0.090" which negates most of
the advantage of the quench design.
FWIW, the 360 with magnum heads I built for my 68 Barracuda has the block
machined for zero deck, that is the top of the piston is even with the top of
the block. The head gasket I am using has an 0.039" compressed thickeness
making the qunch distance 0.039". Even with 10.6:1 compression in this engine I
have no detonation problems and the engine runs fine on 89 octane middle grade
fuel. Once I get a few more miles on the engine I will be experimenting with 87
octane to see if I can save a buck or two on a fill up. The open chamber heads
that came on the 360 would have detonation problems with 93 octane at 10:1
compression so the quench design really seems to work. BTW, I do not have a big
cam in the engine, it's a 268/280 duration with a little over .5" lift with the
1.6 ratio magnum rockers. Estimated power is 375HP.
Dave Clement
99 SLT+ CC 4X4
In article <b26be6d905082213314909d013@mail.gmail.com>, andy.levy@gmail.com
(Andy Levy) writes:
>
>
> On 8/22/05, Terrible Tom <SilverEightynine@aol.com> wrote:
> >
> > B1LLYW@aol.com wrote:
> > > In a message dated 8/22/2005 3:51:47 PM Eastern Standard Time,
> > > SilverEightynine@aol.com writes:
> > >
> > >
> > >
> > >>My gut is to go with 5223's - for whatever reason they are calling for
> > >>the 522 family of plugs and not the 392 family, so I should stick with
> > >>that right?
> > >>
> > >
> > >
> > > Go with the 3923's.
> > >
> >
> > Why?
>
> Because.
>
> If you're getting some mild pinging, the 3923s should take care of it.
> If most of your driving doesn't get your engine up to full temp
> before you're done, then stick with the X224s. The 592x has an
> extended tip in comparison to the 392x, so it'll reduce the combustion
> chamber volume slightly which *could* have the engine more prone to
> ping, if I recall the discussions from years ago correctly.
>
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