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Some time ago, I asked the
participants of the Dodge
message board for suggestions on how to get better performance (good
low end torque and reasonable power) from a pre-Magnum 318 V8.
Below are excerpts from the
discussion that followed:
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lugantom@off-road.com
wrote:
I'm doing some planning for my engine, and could use some advice:
Option 1: New heads and cam for my 318. Direct Connection used to sell
W2 heads which made these engines perform much better. Anybody out
there know if MoPar Performance sells something similar now? Anybody
want to recommend heads and a cam?
Option 2: Drop in a 360 short block with appropriate MoPar Performance
heads & a cam; keep my Performer Manifold, carb, headers, etc.
Swap the driver's side mount & the torque converter.
Option 3: MoPar Performance Magnum Crate Motor. Dunno what's involved
here, but engine alone costs about $2500 discounted.
Anyone care to comment/advise?
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Mike in Alaska wrote:
No No No No No! All those other posts are all wrong!!! (Just kidding!)
Forget about W2 heads, they are for all-out racing. Way back in April
1988 Hot Rod did an article called 318 street recipes and built up
quite the impressive small block. To make a long story short the
results were: 331hp 9:1 comp. .455" lift cam. 1 5/8"
headers. 750cfm carb. This may be an old part number, but the cam was
P4286671. Heads: P4452748 - fully ported and complete w/valves and
springs. Keep your intake and carb. You may opt for a slightly smaller
cam. This is a good route if you want to save bux. Otherwise get the
crate 360!
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Kirk wrote:
With all due respect, I thought we were talking about low end torque,
climbing steep grades, and decent gas mileage. Ididn`t realize that
you were talking about a street machine. The above STREET RECIPE
should per form well in a 4500 lb. truck. 331 H.P. 455 lift , 750
C.F.M. Now wer`e talking gas mileage! Dont forget the 2, 000 stall
converter.
Honest, I`m not trying to be sarcastic, I`m just trying to get your
attention!!! Over camming and over carbing, and just plain over
building, has been more frustating to more people than you can
imagine. If your`e going to try to build that 318, do yourself a favor
1) Figure out just what it is that you want from this engine, what
R.P.M.range you want to operate in.
2) Call Edelbrock, or a professional engine builder, and get their
advice.
There is a Big difference betwen a street engine and a torque motor.
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LJ wrote:
Finding a good set of 360 heads with an RV-type cam would probably
work wonders with a small 4bbl. I've towed my car hauler with mine
just stock and its ok, but it doesn't set the world on fire. We're
gonna go with the new 318 heads from Aero ($349/pair) that includes
valves, seals, springs etc. ready to bolt on. They also have 360 heads
for a little more cash. Plan on using the RV-type cam from MP and a
Performer intake/carb. For a parts chaser, we're looking for mileage
yet be able to tow the car a couple times/year.
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Clay wrote:
Option 2 sounds good to me. I've heard that the 'J' heads are good
flowing heads . Comp Cam 268H or Lunati Bracket Master II cam should
work good with your Performer manifold and headers. IMHO, I wouldn't
go over 230 degrees @.050 for a cam in a Ramcharger, they're too heavy
. Cams that start making power above 2500 rpms aren't very good in
heavy cars because getting a 5500 lb. vehicle to take off takes alot
of torque (unless it's geared REAL steep ). A cam that starts making
power off idle to 3500 rpms would be good for a daily driver. But, if
you spend most of your time above 3500-4000rpms, get a bigger cam
that's made to operate in those rpms. Does this make sense?
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Mike in Alaska wrote:
I know you are all hot to get that motor beefed up, but if you put new
heads on an old '83 block without rebuilding it, the rings won't take
the extra power. I know you put headers and a manifold on, and this is
fine, but cyl heads (even a valve job) will probably be too much
pressure for that tired block unless it has been rebuilt lately. You
don't necessarily need to go with expensive parts, just freshen the
thing up... piston + rings, bearings, grind crank, and definitely get
the rotating assembly balanced. Save your money and spend it on doing
things right the first time, you'll be glad you did.
Go to the parts counter at the local Dodge dealer and for about 5 bux
get the latest catalog from Mopar Performance. This book also has the
tech hotline (1-810-853-7290). These guys have a paycheck that rides
on you getting the best info on hi-perf mopar stuff.
W/axles, I'd look into the feasibility of putting in an overdrive
transmission first. Then you can utilize much steeper gears without
hurting gas mileage too much. Make sure whatever you do w/axles, that
what you put in has BIG brakes... tall tires (even 31's) are hard to
stop when brakes get wet, muddy, etc.
Try and do as much work yourself and put the cash into parts, not
labor. I know it is hard if you don't have access to a garage, but do
what you can. This way you also learn what to do and can fix stuff
when things go bad off-road.
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Terrence wrote:
As I've recently worked through similar questions, I thought you might
be interested in what I'm doing. I started with a compression test. I
believe performance enhancements cannot make up for poor compression
or a tired engine. My engine has 80K miles on it. The compression was
okay, but indicated the need for a valve job. I would rather put my
effort into improving traction, tires, suspension, diffs---things that
let you better use the torque you have--but since I'm in for pulling
the heads anyway, I wondered what was pracical to improve engine
performance. I decided to model the Lil'Red Express: dual snorkel air
intake; TQ 850 CFM; police intake manifold; heads and cam from '68
340; and a free flowing exhaust system.
The key is the heads (valves 2.02i/1.6e). My options: get the heads
off a '68-'71 340 (none local; aftermarket heads of similar spec;
machine a set of "J" heads to take the larger intake valve;
keep my exisiting "J" heads (1.88i/1.6e) and compensate with
the cam. The last is what I chose because it's practical and fits my
budget.
Cam selection used to be easier. You bought Isky or Crane from your
local speed shop. It still can be--I called up the local shop and
relied on Joe (who coincidentally had been working on his girlfriend's
RC). He asked about the truck, how I drive and what I was going for.
Joe went through the catalogs and said he would use a Crane Max
Velocity. He liked it because it was a newer computer modeled design,
had high lift/higher on the exhaust, and a power band from 2000-4500.
I then did some comparisons:
Cams for LA Series Lift Dur Dur@.50
Stock Dodge/2bbl .410/.410 252/252
Summit K6900 .420/.442 262/272 204/214
Edelbrock Performer Plus .420/.420 270/270 204/204
Stock Dodge/4bbl .430/.444 268/276
Summit K6901 .441/.441 276/286 218/228
Lil' Red Express .444/.453 276/284
Edelbrock Torker Plus .447/.450 306/316 272/232
Crane Max Velocity .454/.480 272/284 216/228
Edelbrock RPM .488/.510 308/318 234/244
Somewhere I read that for low end torque you want short duration and
high lift, and that the problem (at the low end) in getting the
air/fuel mixture in, is getting the exhaust out. Comparing against the
listed cams and especially the 'Express, the Crane made sense. I then
calculated what a power band of 2000-4500 means in MPH with 31"
tires and 3.55 gears in low range.
Gear/RPM 2000 4500
first 4 9
second 8 18
third 5 33
fourth 26 52
I can drive with that, so I bought the Crane kit for $155. I believeit
will let me obtain performance comparable to the Lil' Red Express.
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I had a few questions to
Terrence:
1) Are you starting with a 318?
2) Has your cam selection been influenced by manifold selection? Do
you actually have the Lil' Red Express police interceptor manifold?
3) What are your exhaust plans? I've invested about $425 in headers
and a custom dual exhaust (but still no crossover pipe).
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