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

["Steve Galezowski" <stevenlulu@xxxx>]

Bill:

On the cam, I used an Xtreme Energy 262/270 cam. It has .462/.470lift. So I
didn't have any piston to valve clearance problems. I chose a fairly small
cam for all the reasons you stated. And another thing too is that if I'd
gone bigger, then I would have had to started thinking about a high stall
converter, gears (I have 3.23 posi) and then you get into transmission
coolers etc...

When we built up the motor, we were not sure if the 6-pack manifolds would
fit because of the rear exit. When the motor was installed there was
interference at the firewall on the drivers side, but really minor, just
against the firewall seam. So we simply banged the seam in with a hammer,
I'd say less than 1/4" in, along maybe 3" horizontally. The paint didn't
even come off.

On compression, it of course depends a lot on cam size, weight, gears and
spark timing. I have a 66 Vette with aluminium Performer RPM heads and 10.25
compression. It has a 264/268 Xtreme Energy roller cam and fairly aggressive
timing. 92 octane just doesn't cut it so I add octane boost. I could cut
back on the timing and maybe 92 octane would be OK but, hey, its a vette and
I want power. But the 300L is more of a cruiser, and I didn't want to be
schlepping octane boost around with it too. Plus I kept the iron heads and
it's a heavier car. And I had about the same size cam and gears in both
cars. So I backed off to 9.5 compression and it runs great on 92.

I can't comment too much on your GTX other than to say that from what I have
heard, OEM compression specs were often as much 1/2 point higher than what
actually came out of the factory. As you said the only way to know for sure
is to cc the heads....

Steve Galezowski
300L






----- Original Message -----
From: "William Huff" <whuff@xxxx>
To: <Chrysler300@xxxxxxxxxxxxxxx>
Sent: Friday, February 07, 2003 11:43 PM
Subject: Fwd: Re: [Chrysler300] alum head or current heads- reasked


> Hi again,
>
> Just a couple of more thoughts on the subject to add to the good advice
> from Steve. After looking inside my 300D, and my non-letter (gasp!) '70
> 300, I sort of thought that the C bodies probably have pretty good hood to
> carburetor clearance. When I used the Performer RPM in my GTX, clearance
> was a slight problem, to avoid rubbing the hood, I use a Summit low
profile
> foam type air cleaner.
>
> I can tell you that from installing the Performer RPM manifold and
having
> the Holley 750 worked over by the Carb Shop, I was astounded at the seat
of
> the pants increase in acceleration from those two changes alone. I agree,
> vacuum secondaries are a must. I wasn't sure car had ram manifolds or
not,
> or if the gentleman had intended to stay with them if they did, but for
> performance on the street, I would certainly use vacuum secondaries and
> have the carburetor(s) worked over by a competent performance person.
>
> The reason I didn't mention the Xtreme energy or the Hughs dual pattern
cam
> is that I have read that valve-piston clearances can become a problem with
> OEM pistons as the lift approaches .500". The advantage of having the
> quicker opening and closing is to get more lift without increasing
duration
> markedly. The purple cam hemi resto cam is in the .467 lift range, I
believe.
>
> Steve, I am interested in the fact that the B body manifolds fit the C
> body. I have the engine and tranny out of the '70, and since it
originally
> was a 350 HP 400 cid engine, the manifolds were the crummy log type. I
had
> some HP manifolds from a '68 B body, but finally got a HP C body driver
> side manifold for a premium price on eBay. Since the driver side manifold
> for the B body exits at the very rear of the manifold, where the C body
> exits from between cylinders 5 & 7, I didn't think the B manifold would
> fit. It is impossible to tell until the engine is ready to go back
> in. Were there any interference problems fitting them in?
>
> I certainly agree about the mufflers, the thrill of that big roar
following
> you around can diminish very quickly. However, I believe, based on some
> testing done in some of the Mopar mags that even with cast iron exhaust
> manifolds, the larger free flowing exhaust can yield real performance
> benefits. At the very least, I would ensure that the tailpipes were the
> same diameter as the exhaust pipes, which are probably 2 3/8". There are
> some mufflers that flow very well and are not that loud, I can't locate my
> reference on that right now. Also, making sure the tail pipe ends
protrude
> well beyond the body can reduce the chance of reverberation and
> resonance. Turning the tips down also reduces reflected sound.
>
> Dick Landy (of drag racing fame) writes a column in one of the Mopar mags,
> and I have seen several instances where he has recommended milling the
> heads to get approximately 10:1 compression on street engines when the
> cheaper pistons with lower compression heights were used for a
> rebuild. Admittedly, this is not for everyone, but for the performance
> minded. As you know, unless you cc the head and cylinder volumes, you
> really don't know what compression ratio you have, just guessing. My GTX
> still has the factory 10.5:1 pistons in it, and it runs great on pump gas,
> but I must add that the high gear ratio of 4.10:1 means the engine is
> seldom heavily loaded. With a large heavy car and a low gear ratio you
may
> well be right in using a little less than 10:1.
>
> Amen to using gauges and looking at them often.
>
> Bill Huff
>
>
> >>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
>
>
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