Re: [Chrysler300] Can't Get Good Gas Anymore?

[Andy Mikonis <r41hp@xxxxxxxxx>]

Chrysler originally specified the colder plug for 375-hp 300F/G, which is Autolite A32. 

(I'm looking at the "MOPAR SPARK PLUG CROSS REFERENCE AND HEAT RANGE CHART" in the "Genuine Mopar Fast Moving Parts with Universal Application" book, February 1961, 81-690-0160)

Autolite 85 is not the same heat range, it's just all that is offered now. I used to run Autolite 84 in the 1980's, but you can't get them anymore - I think I still have a set on the shelf. AC R43 was another one in the colder heat range I had luck with, but I don't see them anymore, either. Not sure about the evolution of Champion numbers.

Interesting about the NGK's. A lot of the E-Type guys swear by them (yes folks, that's a JAGUAR!)

Andy Mikonis
in soaked and steamy Chicago


--- On Thu, 7/28/11, Tony Rinaldi <awrdoc@xxxxxxxxx> wrote:

From: Tony Rinaldi <awrdoc@xxxxxxxxx>
Subject: [Chrysler300] Can't Get Good Gas Anymore?
To: "Chrysler 300 Club" <Chrysler300@xxxxxxxxxxxxxxx>
Date: Thursday, July 28, 2011, 8:49 PM







 



  


    
      
      
      Hi To All,



Leaded High Octane Fuel is no longer readily available.



{Before you delete this message, here is the bottom line: use colder spark

plugs with today's bad gas}



Gone are the days of the 99 octane or better gas.



Newer unleaded fuels burns hotter. Add ethanol and the fuels burn even

hotter. 



What do we do with our high compression, high performance engines? They

burned hot with the gas they were designed to run on. They burn even hotter

with today's pump gas.



Short of using racing gas and octane additives, we use 93 octane, if we can

get it. And we retard the spark. This eliminates detonation, associated with

lower octane, that is destructive to the engine internal parts.



But when we retard the spark to avoid pre-ignition, we further increase the

heat in the engine especially in the exhaust manifolds. The retarded timing

will allow the majority of the heat (Flame) to blow out of the exhaust

instead of keeping it in the cylinder to produce power.



Too hot of a heat range of the plugs, usually recommended for our engines,

indirectly leads to a runaway pre-ignition condition that can increase

engine temperature. We then have to retard the spark even further creating

more heat in the exhaust manifolds.



Heat from the combustion chamber escapes through the exhaust gases and the

side walls of the cylinders.



Ever wonder why we repeatedly have exhaust manifold leaks or we have boiling

gas in the bottom of our exhaust heated crossram carbs on really hot days?



We are generally limited in the availability and selection of spark plugs.

This means that we are using plugs with heat ranges that were good for

1960's gas not today's gas.



Not sure how well this subject has been covered in the past, but my race

mechanic shared some of the work around techniques that the NASCAR people

are using to deal with the elimination of leaded fuels in recent years.



In hotter heat range plugs, the tips remain hotter between firings and start

acting as glow plugs. The cylinder mixture will tend to prematurely ignite.



The use of newer spark plugs with colder heat ranges is a good option to

help relieve low octane detonation. These plugs fire with the same intensity

but have more insulation. This dissipates the heat from the tips quicker

thus eliminating pre-ignition.



A heat range refers to how much heat a spark plug is capable of removing

from the combustion chamber.



NASCAR is so big, spark plug manufacturers listen to them and are

manufacturing colder heat ranges.



The more internal modifications that are done to make our engines more

powerful, the more heat the engines generate.



Domestic plug manufacturers use designations where the higher numbers are

hotter heat ranges and the lower numbers are cooler.



NGK numbers are the opposite. 2 is the hottest and 12 is coldest heat range.



The NGK R5670-6 V-Power Plugs (NGK Stock #2746) for Big Block 413-426-440

(Raised Deck) with iron heads or Standard NGK Plugs XR5 (#3339) are close to

the heat range of an Autolite 85 which is the replacement plug for the

original A32 for wedge crossram engines. There are no heat range choices for

the Standard NGK XR5 plugs. The R5670 V-Power series of racing plugs do have

colder ranges however.



The rule of thumb is to use the coldest heat range plug that you can run

without fouling. NGK V-Power plugs are known for not Fouling readily

especially with the projected tips on the R5670s. Reference the following

quotes below about NGK V-Power plugs:



"These NGK V-Power spark plugs offer economical performance for nearly any

automotive application, and are the only plugs with NGK's V-Groove

technology. They enhance ignitability, lower the voltage requirement of

ignition systems, and have strong anti-fouling characteristics, while

improving fuel mileage and acceleration performance. The V-Power plugs also

are highly durable against electrical and chemical wear, making them a

long-life replacement plug. Because of the V-Groove, the spark occurs at the

edge of the center electrode. So heat is not absorbed by the electrode

itself. This allows the flame kernel to expand quickly and efficiently for a

complete burn and great performance." strokerengine.com



"NGK's V-grooved center electrode moves the spark to the outer edge of the

electrode for improved ignitability in all combustion chamber conditions.

This configuration is especially helpful for throttle responsiveness,

quicker corner exits, and more power on the bottom end in a drag race

engine. The high-purity alumina silicates used in the insulators of NGK

Spark Plugs helps keep the spark plug tip warm enough to burn off deposits

at low-speed, yet still be able to transfer enough heat during high-speed

operation to prevent detonation and pre-ignition.: NGK



"I have two cars with 440 engines and one car with a 360. Both 440 engines

were rebuilt and placed into service with Champion plugs in them. Both

engines fouled atleast one plug before they even had a hundred miles on

them. At the advice of a friend that owns a parts store, I went to NGK

V-Power plugs. No more fouled plugs. And my 360 that I rebuilt 6000 miles

ago also has the NGK V-Power plugs and hasn't fouled any." Mopar Enthusiast



Check your exhaust manifold temperature before with your existing plugs once

the engine is at operating temperature after a good run. You may want to

check and record other areas of the engine as well as take note of the

temperature gauge.



Harbor Freight sells a laser heat gun for about $20.



A good plug to consider starting with is one that is 2 heat ranges colder

than you are running now. NGK R5670-8 (#3354) V-Power plugs should do it.

About $20 for 8. They come in packs of 4. Then advance the timing.



If your engine has been rebuilt with lower compression, consider trying the

NGK R5670-7 (#2891) (one heat range cooler) to make up for the lower octane

unleaded fuel. Then advance the timing.



If you only can get fuel that is lower than 93 octane, add one more heat

range cooler than recommended above.



After you have installed your cooler plugs and advanced the timing

appropriately, check the exhaust manifold temperature in the same spot, as

well as your other reference points, once the engine is at operating

temperature after a good run.



The temperatures should be less and the drivability of your car should be

better.



My engine was built with larger cubic inches. I went to a NGK R5670-9

(#3913). 



Do you expect a different result by doing the same thing over and over

again?



Been there done that!



Did something different this time. It worked.



Tony Rinaldi

300-F Conv't





    
     

    
    


 



  





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