Re: [Chrysler300] alum head or current heads- reasked

["Steve Galezowski" <stevenlulu@xxxx>]

Excellent response, Bill. Your recommendations conform very closely to the
specs on the 413 in my 300L (and may I also compliment you on your use of
real sentences, with capital letters too!).

A few comments I would add:

-Be careful with hood clearance with the Performer RPM intake. I used the
regular Performer intake for that reason (although I didn't check the
clearance on the RPM).
-With an auto transmission, I recommend a carb with vacuum secondaries. Then
you can just mash the pedal off the line without any bogging.
-I used a Holley "Street Avenger" 670 CFM on my 413. On a 440 a 750 CFM is
probably plenty big unless you are going with a really big cam which would
be a mistake for the street.
-Think about using one of the latest design cams such as Comp Cams Xtreme
Energy. They open & close the valves more quickly so you can use a shorter
duration cam & get bigger-cam flow.
-You can't get off-the-shelf headers to fit a C-body (at least not a '65).
Custom is expensive. I swapped my stock exhaust manifolds for those off a
440 6-pack which flow better. If you are using stock exhaust manifolds, a 2
1/2" exhaust is redundant since the stock manifolds are restrictive. In that
case I would use 2 1/4" pipes. Also the smaller pipes will reduce your
exhaust sound level.
-Get quiet mufflers. I first tried Flowmasters and they were way too loud!
With a breathed-on big block, big pipes and a C-body you can get a lot of
reverberation in the passenger compartment, especially when you lift off the
throttle.
-Install a 160 degree thermostat and make sure your cooling system is up to
snuff. This gives a little more room to advance the timing.
-I would keep the compression ratio around 9.5:1 with iron heads and a
medium size cam. Then you can still add some timing and run on pump premium
gas 92 octane. At 10:1 compression you'll probably have to back off on
timing and/or use octane boost additive.
-Install oil pressure and temperature gauges under the dash. Don't risk all
that money in the motor on idiot lights.

Steve Galezowski
1965 300L

Original Message -----
From: "William Huff" <whuff@xxxx>
To: <Chrysler300@xxxxxxxxxxxxxxx>
Sent: Friday, February 07, 2003 3:34 PM
Subject: Re: [Chrysler300] alum head or current heads- reasked


> If I understand what is going on, he is asking whether to continue with
his
> iron heads or wait and purchase the Edelbrock aluminum heads. IMHO, the
> Edelbrock heads would be a waste of time. It is true, they outflow
> everything except maybe the MOPAR stage VI heads and the INDY heads, right
> out of the box. The problem is that one generally needs to make other
> modifications to utilize that extra flow.
>
> The cam profile must change, certainly a lot more lift, and probably a lot
> more duration. Most of the difference in flow comes in the higher valve
> lifts. This means the engine will then be making maximum H.P. and Torque
> at a considerably higher RPM. This is usually to the detriment of the
> lower "off the line" performance of the vehicle, unless the rear end ratio
> is changed, say to a 3.70:1 or a 3.90:1. Try cruising with those ratios,
> you would have 3000 RPM or better at highway speeds. Been there, it isn't
> fun and its tough on the car. Even after all that, if you tried to use
> this new found horsepower with the lower gear ratio from a stop, you would
> find that the rear suspension and rear tires needed modifying to put the
> horses on the ground. My '67 440 GTX is a much lighter car than my 300D,
> but with 4.10:1 gears, any time I floor it and it downshifts below 35-40
> mph, it's smoke city from the street tires. This is with a basically
stock
> engine.
>
> The 300s are heavy brutes, they respond to low end torque and
> horsepower. A good RB engine matches this profile with its relatively
high
> HP and Torque at lower RPMS. A good RB will probably beat any similarly
> prepared Hemi (392 or 426) for the first half of the quarter mile. That's
> an eighth mile. This is because all the horsepower and torque are
> available one or two thousand RPM lower. Later, when the Hemi (or any
high
> RPM engine) begins to make their real horsepower, the story can
> change. Unless on a race track, you would probably never be flooring the
> gas pedal for that long, so play to the engine's strengths.
>
> I have found (following the old Direct Connection Engine buildup
> instructions) that the big block heads respond to minor valve and bowl
> relieving, port matching (intake mainly). Get the Mopar Performance
> porting templates, if you don't have the confidence, get someone to use
> them to open the heads up a little. Use the Mopar purple cam shaft with
> the street hemi/440 magnum specifications and recommended valve springs,
> use around 10:1 compression and premium fuel. This cam will peak around
> 5300 -5400 RPM, but will still be making lots of power up to around
> 5800. Use a good high rise intake such as the Edelbrock Performer RPM
with
> a 750-800 CFM carburetor, Have a knowledgeable person jet and maximize
the
> carb for your application. Recurve the distributor to bring the advance
in
> a little earlier. Invest in a custom 2 1/2" exhaust system with mufflers
> that flow well. Either use headers or find the HP C body exhaust
> manifolds. Make sure you have the limited slip differential. I think you
> will end up with a nice comfortable 300 that will absolutely surprise many
> a "fast car" from 20 mph to whatever you care to push it to.
>
> Sorry this post is so long, I just got to typing and couldn't stop. Hope
> my thoughts help you come to a good decision that will allow you to invest
> wisely and still retain the enjoyment of the car.
>
> 300ly,
>
> Bill Huff
>
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