Performance-LA and B series engine

Where to start and what to do with your engine
The 3 C's of Hot rodding applies to truck engines to. Carbureation, compression, camshaft all help
to increase engine power. Carbureation is pretty
easy, most small blocks will be in the 625 cfm area
and big blocks like 750 cfm+. The compression equation has to be looked at before camshaft. The
compression of an engine determines the thermal efficieny of the motor. More squeeze= more power,
the limit is today's fuel, being really poor quality
compared to even the regular of the late 60's.
One must take into account the altitude of operation, the use of the vehicle(engine speed) and
the cost of operation when deciding compression ratio. Its fine to biuld a 13.5:1 max wedge for your
short box, but if you have to drive more than 80 miles in it on a regular basis you'll go broke buying gas for it. Truck engines especially 4x4's
should hold the CR to a maximum of 9.5:1, that is
the limit of premium fuel without having to retard
the timing into last week.
Camshaft profile is dependent on compression ratio.
Put to much camshaft into an engine and it kills
the cylinder pressure which in turn kills the power or makes the engine "peaky". To small a camshaft with high compression makes the engine detonate severely.
Its a fine balance, that sometimes requires buying a few parts to make things work.

Stock amd Performance Engines
With stock motors that are in decent shape, the
place to start is exhaust, duals or headers can make a significant improvement in the output of an engine, although don't use large tube race headers.
After exhaust, get into the carb, if you have a 4 bbl setup already, your are halfway there, if not get a dual plane aftermarket intake, for the small blocks a late 70's cast intake is hard to improve on. The addition of the free flowing exhaust tends to lean the engine out through better scavenging of the cylinders, production carbs are lean to begin with, so stepping up the jets a few points can make the engine really come alive. The best aftermarket
carb is the edlelbrock performer series, lotsa parts available and easy to tune. My next choice is the thermoquad, the most misunderstood carb on the planet. YOu have to make your own strip kit, but with the huge secondaries not much out there will outperform it on the street. The holleys are can of worms, lots of parts but it takes lots of patience,
and know how. A few dodges came with quadrajets,
finding a good q-jet is getting tough, they are prone to throttle shaft wear and they have a probelm with body becoming pourous, if you are brave the q-jet may work for you.
Camshaft...better check the server space before I start this.. Most engines that are found in Dodge Trucks have low compression, mostly in the 8:1 range. Although chrysler specs the engines higher sometimes, loose production tolerances make them truly unknown most of the time. Most stock 400-440's are in the 7.8:1 range, If the heads have been off the engine and aftermarket head gaskets used, the CR will be around 7.5:1. 318's are typically around the low 8's while 360's are in the same range as the 400-440. while not great for performance, the low compression allows the engine to be lugged at low rpm and it reduces the oxides of nitrogen in the tailpipe, both makes the vehicle pass emmisions testing easier. The stock camshafts have a short duration design to keep the cranking pressures semi reasonable, almost all chrysler cams for the small blocks are 252 duration while big blocks are 260-268 degrees in duration. On small blocks 268 is about the limit for a stock engine with decent gearing and
power accessories, on a big block the cam can be pushed into the 278 area with decent driveabiliy.
On smaller cams its best to go by the advertised duration, the duration at .050 is really menat for big cams where the starting point of the lift is undistinguishable from the base circle due to the length of the ramp.
Camshaft notes: All cams have a recommended spring
pressure, FOLLOW THE GUIDE THAT COMES WITH THE CAM.
Degreeing is always necessary, its a good way
to find a screwed up dampers of twisted crank, never
install and forget even when using a stock cam.
Throw the stock timing chain away, use a double roller with a hole for the cam pin and not a slot.
Stock engines will need a faster advance curve to make use of the cams full potential, Leaving the ignition stock is like putting a subwoofer on an AM radio. When choosing a cam pick conservatively, get
the specs from your stock cam to compare, lift doesnt really mean much, its duration and overlap that have the greatest influence, a few degrees more makes a huge difference in the way an engine behaves. When it comes to Mopar engines, Mopar camshafts work the best, if you want more jam from you stock lo-po motor, use a factory HP grind, they have alot of research time biult into them.
Watch out for house brand cams and repop cams, they were designed on chevs and dont really work that well in Dodge engines, the Dodge has a much larger lifter that allows the cam to have a more aggressive ramp, which means the Dodge cam can have more lift in a shorter duration lobe.
A few manafactures other than Mopar are making cams
to take advantage of the larger lifter. Hughes engines and Ultradyne both make Chrysler specific cams.
I have found that for every 10 degrees of duration are added to the camshaft the cylinder pressure
drops about 5 psi from stock, so keep this in mind
when adding a 298 degree duration camshaft to
a stock 360 that only has 110 lbs of cylinder pressure before the cam is installed. The cranking pressures will be in the 70-80 range and the engine
will be a dog.
The rear gear ratio plays a huge part in proper
camshaft selection as does the converter stall speed. Just as a 4 speed manual transmissions tend to mask the problems of larger tires, they will also tend to cover poor cam and rear end gear selection by allowing you to rev the engine higher before shifting, change gears on demand to meet engine torque peak and allow a higher starting rpm. Automatics have preprogrammed shifts
except for manual valve bodies, and the addition
of a torque converter with a higher stall speed lets
engine flash up to a given rpm before the stator in
the converter starts to propel the vehicle forward.
This allows and engine with a big cam and no low
end power to get up to the start of its powerband
before it is loaded with the vehicle mass. For an
example a mud truck needs lots of tire speed and
high winding horsepower, the engine is a 440 with
10.5:1 compression and a 312 degree cam, the idle is
850 rpm, intake vacuum is 6" hg, while this engine
sounds realy raunchy, the truth is it wont make any power till at least 3500 rpm where the torque and
horspower would go from a flat 220 hp and 240 ft/lbs of torque to 460 hp and 425 ft/lbs. These number would start going way up from 3500 rpm, however with
say 4.10:1 gears and 40 " tires, its not in its power band from an idling standing stop to the end
of the bog, however if the truck can leave the line
at 3500 rpm where it starts biulding power and then the engine is loaded, it will be able to accelarate the tires upward
from that point onward and provide enough HP to keep
the tires spinning and clean.
A stock engine with high converter stall speed is
useless at best, since a stock motor is designed
to give mostly low speed torque, a high speed stall
converter would just soak up much of the engines
power and turn it into heat due to slippage.
In summation, when picking a cam, look at its
powerband numbers closely and its compression requirements. If your vehicle cruises at 1800 rpm on the highway, you need a 1200-4000 rpm camshaft, where if it cruises at 3500 rpm on the highway a 2500-5000 rpm cam will be pretty close.
The cruise rpm relates to compression requirements
although sometimes they are not in the cam catalogs,
Here is a rough guide to compression vs cruise rpm
7.8:1-9:1 ------- 1200-4000 rpm
8.5:1-9.5:1------ 1800-4500 rpm
9.0:1-10:1------- 2200-5200 rpm
9.5:1-10.5:1----- 2800-6000 rpm
This gives an approximate guide to how much
cam your engine will handle
IE: 1/2 ton with 3 spd auto, 33 inch tires stock
318, rear gears 3.23:1, compression 8.2:1.
Cruise rpm is 2100, cam book lists 262 duration/.431 cam good for 1200-4000 rpm, and 284 duration 484 cam good for 2500-5000, the trucks
cruise rpm is outside of the seconds cam range
but is inside the first cams power window, and
8.2:1 would fall within these parameters.
If you want that big rough idling cam, kiss
your power brakes goodbye because the bigger the cam, the less Idle vacuum, be aware that
84 and later dodges use vaccuum for the HVAC controls on some models and CAD axle systems on all 4x4's, the big cam vaccuum will stop these systems
from working properly or cause intermittent axle
engagements.

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PISTONS, COMPRESSION AND CRANKSHAFTS

Factory pistons, usually cast, have come in all
shapes and forms. If you look at the stock
engine specs page, or a year by year listing of
performance for Dodge engines, you will soon see
that after 1971, Power was almost down by 50% for
all v-8's. There was no real big cam change or anything, in fact the heads after 72 got better with
the exception of the 340 and 440 heads. The biggest
change was compression. For the most part 72 and later engines will have dismal compression, stock
440 spec for mid 70's is 100 psi cranking pressure, pretty sad. Anyway, the thing to do is get the engine regardless of size out fo the 7:1 range, shoot for a max of 9.5:1. I just roasted my 440 thanks to bad fuel and a 9.7:1 ratio, the cast pistons just could not take the abuse of detonation.
I suggest aiming for 9:1, with regular carb and ignition, If you chose to go higher, have deep pockets, EFI and a cockpit adjustable ignition.
The new plan for my motor calls for 9.2:1, and maybe 500 cid, this is going to be done with a stroker crank.
Stroking the 440 and the 400 has become a common occurence, while it is cheap to stroke the 400/383
the 440 is considerable more money because the crank is not a factory piece. THe 400 elongated with the
440 crank becomes a 451, while the 383 becomes a 426
which is kinda neat. The 440 becoms a 478/500 depending on stroke and bore. While I am not sure yet about the 440 stroker combinations, I have some reservations about the 400/383 packages. The 451 pistons that I have seen, have extremley short skirts when compared to an oem piston, while this may seem good to lesses the reciprocating wait, a shorter piston is more prone to piston wobble than
a long skirt piston, this may decrease the durability of the engine making it a 40,000 mile rebiulder instead of a 140,000 mile rebiulder.
The 451 seems to do well in racing applications, but for a truck, in miy mind its to clos in cid to a stock or bored 440 to make it worthwhile unless the
parts were cheap(read free). The stroked 440 would be a more attractive motor, especially when the 500 cid range is topped, 540 cid dodges sound really neat and make a 440 look like a small block on the dyno