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High Performance Tips/Tricks

Engine Swaps
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 Dodge Trucks.

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:

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:

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.

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.

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.

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.

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 page.

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.

Electronic Ignition
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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