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High Performance Tips/Tricks
Commonly, owners of '61-'71 Dodge Trucks are looking for a higher level of
performance then their trucks currently offer. Although hopping up a
small motor is quite possible, "There is simply no replacement for
displacement." Here is some information and tips on Engine Swaps for '61-'71
There are a number of considerations that you'll have to consider when
swapping engines in '61-'71 Dodge Trucks and A-100 Compacts. Overall, the
best way to go about such a swap is to have a great deal of research materials
and references at reach so you know what you're getting into. This can
include Books, Magazines, wiring
diagrams, and even junkyard trucks with the engine you plan to upgrade to.
All of these things will allow you to evaluate the necessary changes you'll
have to make and where to make them. Briefly, you'll have to consider
the following items:
- Cooling - includes radiator, tranny cooler and lines, water pump,
hoses, and pulleys.
- Engine Accessories and Control Systems - including throttle and
tranny linkages, A/C or power steering, and other accessories.
- Exhaust - with regards to pipes, mufflers, headers and/or manifolds.
- Mounts - these apply to both the engine and transmission and can
depend not only on the proper setup but also the current chassis configuration
(crossmembers, shifters, 4wd, etc.)
- Electrical and Ignition - in regards to the number of cylinders and
the type of engine before and after. This includes the starter, alternator,
igniton and necessary wiring changes.
- Driveline and Transmission - here you will need to consider the size
of the new engine and a proper transmission to handle the power it will
provide. Also, four wheel drive trucks will be further limited in transmission
selection (mostly due to length and transfer case setup). Other items in the
tranny department of swaps include bellhousings, linkages, cooling and hoses,
and mounting hardware.
- Oilpan - in regards to suspension clearance.
- Extra Fabrication - if necessary.
LOCATING THE NECESSARY PARTS Usually, the best way to get the
parts needed for a swap is to have the entire engine setup from another
vehicle. This may mean watching the papers and waiting for grandma's old
station wagon with a 440/727 combo to go up for sale. Once you get a hold of
a donor vehicle, you have all the parts necessary to run the engine (pulleys,
carb, distributor, etc.) plus a few more to sell or use elsewhere in the swap.
If this isn't feasable, junkyards usually have well used but suitable
engine/tranny combos for sale. For the most part, motor specific items aren't
a terrible problem, however, some things will have to be located to properly
mount the engine. These include:
- Motor and Tranny mounts
- Oil Pan (one that will clear the front suspension at full travel)
- Possibly a correct radiator (if a donor part simply won't fit: also
depends on transmission choice)
- Linkages (for automatic transmissions)
- Driveline (unless one is adapted or fabricated to fit)
The best way to evaluate the changes you will be making is to look at
your current truck's configuration. The biggest concern with an engine swap
is how mounting the powerplant will go, so look carefully at what you have and
how it all works to hold the truck together. Observe the mounts, crossmembers
and clearance involved with the areas around the chassis and engine. Get a
camera and develop photos of the critical areas such as accessory setup,
linkages (very important!), mounts, etc.
Next, try and find a junkyard or friend's truck to reference. This may seem
difficult at first, but if you can find a truck that has (or most likely HAD)
the engine and tranny you are upgrading to, you have the best reference
material available--a factory installation. This only applies to vehicles
receiving the MOPAR to MOPAR swap; any other engines shall be shunned in this
evaluation of the topic. Remember, '61-'71 Dodge Trucks were available with
slant sixes, small blocks, even 383 big-blocks in their prime. The best subject
material can be found in the trucks made after '67 which was the first year
when the LA-series 318 and B-series 383 were available (The 273 was actually
available before this, first in 1964). Take notes and pictures of the critical
setups on the reference truck if possible, these will be used to properly setup
the bigger engine.
At this point, you should check into available parts for the swap. More
appropriately, look into obtaining the motor mounts and the motor itself if
applicable. Motor mounts for small block and big block motors are readily
available from most auto parts stores. If necessary, you may need to fib a
little and ask for the mounts that fit a '67 or later truck (such as the big
block mounts). Don't forget to get the rubber mounting pads for the new
powerplant, these are also crucial to the swap.
Before installing the larger motor, you will probably want to take advantage
of the opportunity and rebuild it. Be sure to check out the section of this
Website devoted to Engines for more
information in that regard.
TRANSMISSION SWAPS Transmissions are next on the list. If
dealing with a small to big block swap, your best possibilities are the A-727
automatic or the T-435 manual with the correct bellhousing. Both transmissions
were OEM equipment on Dodge Trucks from the era, but the A-727 must be the
"block specific" version while the T-435 should be adaptable to both small and
big blocks with the right bellhousing. For example, small block motors will
need the A-727 for small blocks while the T-435 4spd will only require the
proper bellhousing. These items can be found at junkyards in fair condition,
but will certainly need a few repairs or some rebuilding before installation.
Use your discretion.
Whatever the case with transmissions, be careful to keep all the mounts from
the removed and replaced units. In the case of the T-435, the slide in
L-shaped mounts are not readily available from most auto parts stores. On the
other hand, automatic mounts were more generic and are usually easier to
locate, new or used.
Driveline considerations are also in order when it comes to swaps. For the
most part, you will want to locate a similiar driveline from a Dodge Truck if
possible. From that point, a driveline shop can shorten or fabricate an
entirely new driveline to your specs. In some cases, the tranny swap will be
similiar to factory installations and driveline modifications won't be
necessary if the correct unit is located.
Crossmembers are of real concern if you are changing transmissions from
standard to automatic or vise-versa. Dodge used different crossmembers for
their trucks; standard trannies were mounted to a crossmember that was near
the firewall while automatics were mounted on a member further back on the
truck. Most swappers will choose to go to an automatic for convenience, but
this is not always the case. Still, if the truck came original with the
standard transmission crossmember it may hinder the change to bigger and
better. This is where the possibility of fabrication and/or removal of
crossmembers comes into the equation. The best way to handle this is to test
fit the new engine, tranny and possibly parts of the exhaust. If the
automatic definitely needs a special crossmember that isn't there, you can
look for one in a junkyard. It will be difficult to remove and install, but
there are always benefits to factory engineering. Otherwise, a custom
crossmember will have to be fabricated to fit the truck and powerplant.
Automatic crossmembers from junkyard trucks are a possibility on all trucks
of the Sweptline Era, but the `68-`71 trucks all had them. Look for the
crossmember that is 6" from the back edge of the front cab mount. This is
the automatic crossmember you need. It consists of three parts, the main
member and two supports--all of which are factory riveted onto the frame.
Chisel or grind these off and you'll have the crossmember you need. Since
the rivets are no longer usable, simply find some Grade 8 nuts and bolts to
bolt the crossmember into the customized truck.
ENGINE SUPPORT SYSTEMS This refers to the parts that are
bolted to the engine such as linkages for the tranny and carburetor as well as
other accessories. These items are another great reason for having the entire
vehicle that the swapped engine came from. In this way, you will be able to
adapt or utilize the same parts over again. If you don't have the entire car
or necessary items, no problem, just do a little research into the linkages
and support brackets for the accessories you desire. MOPAR Magazines are great for
this kind of research.
The best way to properly adapt the electrical parts you'll be using is to get
a wiring diagram for the truck. This will help you determine what the truck
has built in. From there you can make changes to the new engine or create a
new harness for the different parts that are added. MOPAR to MOPAR swaps
shouldn't be terribly difficult in the electrical area since these trucks were
sparse and yet similiar in their electrical setups.
In general, this section refers to the items necessary to adapt the cooling
system of the larger powerplant. This seems trivial, but it can be much more
complicated in some cases.
Radiators differ for various applications; engine size, transmission, and even
the tonnage of the truck dictate what kind of radiator the truck needs. Engine
size will require a certain size and number of cores in the radiator. Small
block motors require at least a two core unit while the larger motors need
three or more cores to keep them cool. Also, the tranny cooler may be
installed within the radiator itself which requires a special set of lines to
run to the tranny. It isn't necessary to have a radiator with tranny cooling
provisions since aftermarket tranny coolers are widely available. If your
radiator does have them or you happen upon one that does, don't hesitate to
use them for the tranny. Most Chrysler radiators bolt on with two bolts on
each side in relatively the same location on all vehicles. This makes
adapting a non-truck radiator very easy.
A note on radiators. The older style has a rounded top whereas the more
modern radiators have a squared off top. Both have basically the same
four-bolt pattern but the older style is more rare and expensive to repair.
You gessed it, the older stlye is more common on '61-'71 Dodge Trucks.
PUMPS AND PULLEYS Small block motors were available with two
different pumps, one being aluminum while the other was a cast iron version.
The two differ in pulley mounting height and outlet position. The aluminum
pump radiator outlet is on the passenger side of the truck/engine while the
iron version has the outlet on the driver's side. From what I've seen, most
'61-'71 Trucks had the cast iron unit and a radiator to match with the bottom
outlet on the driver's side of the vehicle. Depending on the engine you are
installing, this can pose a problem when one considers the pump in relation to
radiator and the pulley system. If the engine is internally balanced (like
mine), the pulleys may match the iron pump (by way of pulley height) and make
it difficult to change to the more modern, lighter weight aluminum pump. Not
only that, but since the two pumps also differ by outlet, the change can be
even more confusing. Here again, the possibility for success rises if one has
all the good parts (including radiator) from the donor vehicle.
EXHAUST Bigger engines must be able to breathe properly, and
assuming that you'll figure out the air/fuel intake details on your own, here
are some suggestions on exhaust systems with swaps. If you're going for high
performance, check out the in-depth information on the Exhaust Systems
An exhaust system for the engine you're swapping in will probably need to be
fabricated, since the old system is rarely in good enough condition or fit
properly for reuse. Still, it may be a good idea to keep it around (if there
was a donor car) so you can run the truck until you get down to the muffler
shop for a new system. Manifolds for most Mopar engines will fit inside the
cavernous engine compartments, so don't worry about finding a "truck specific"
set just for the swap. Dual exhaust is best for performance and economy, and
is not much more expensive when compared to the cost of a single system.
Image from actual package.
Mopar Performance offers an Electronic Ignition Conversion Kit for small
and big-block engines. This kit includes everything needed to exchange
the inefficient points distributor over to the more modern electronic
breakerless type which Chrysler engineers introduced in 1972. An
electronic control unit, new breakerless distributor and all necessary
wiring is included with complete instructions.
This is one of the few high performance upgrades that has no significant
drawbacks. With the exception of finding a suitable location to mount the
ECU, the performance and drivability gains largely justify the price and
trouble required to perform the swap.
Be sure to check the Parts Sources
page on this site to find out where you can get the best parts and service for
your Dodge Truck.
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