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The 3.8 liter Buick engine is often used in Toyota conversions. This engine has been used extensively in performance and race applications, and as such, there are many hop-up parts and accessories available for the it. The Buick V6 is a bit smaller and lighter than the Chevy or Ford V6s, but is somewhat heavier than the 3.0 liter Toyota V6. Some Buick V6s (odd ifre I believe) have a moderate vibration problem and may tend to run a bit on the hot side.
There is also a turbocharged version of the Buick engine that provides quite a punch for a light truck. However, be cautioned that such a swap requires careful thought to obtain adequate engine cooling especially in cases where the truck will be driven slowly or for some reason have limited airflow. Modification of the exhaust, truck frame, and body will most likely be needed to get this engine to fit.
An engine that has gained considerable swap popularity recently is the 4.3 liter GM Vortex engine. This engine came from the factory in several configurations including: carbureted, throttle-body injected (165 HP), and central-point injected (~200 HP). This is a torquey engine, and uses the same block design as the small block Chevy less two cylinders. Pistons, rods, bearings, etc. are all interchangeable. It also uses roller lifters.
The only flaw in this engine is a slight imbalance condition at about 1200 rpm. About 1993 Chevy revised this engine by adding a crank driven counter-balance to eliminate this slight vibration. Also, engines from the mid '80s and newer use a single serpentine belt with an automatic tensioner.
There is a wide variety of Chevy V8 small blocks available ranging from older Corvette or carbureted muscle car engines to the modern throttle body or tuned port engines. Late model engines can be found in both 5.0 liter and 5.7 liter sizes. Parts selection for these engines is enormous and there are lots of salvage yard engines around.
The small block Chevy V8 is about 4-5 inches longer than the Chevy V6 and weighs quite a bit more. The V8 can be used in a conversion but will require firewall modifications due to the added length and the rear mounted distributor. Installing the V8 also requires that the front grill sheetmetal area be modified and the radiator be relocated forward about an inch and a half. A stiffer front suspension is also required with a V8 conversion and a body lift may be required for distributor clearance, depending on size and style used.
The Ford V6 swap has not really gained much popularity.
Ford small block V8s are shorter and narrower than the small block Chevy engines. Also, the distributor is mounted on the front of the engine, making fitting of a Ford V8 into a vehicle easier than fitting a Chevy V8.
There are a number of Ford V8 engines available, both in carbureted and fuel injected form. By far, those of most interest are the 5.0 liter (302 cubic inch) multi-point fuel injected engines from either the full-size truck line or the performance engines from the Mustang line. There are several companies that are now familiar with setting up the fuel injection systems on these engines to work in other vehicles.
Any of the above engines will fit well between the Toyota frame rails and should allow use of a regular air cleaner under the stock hood. The one exception is the Turbo conversion which will require a 2-3 inch body lift in order to clear the air intake and exhaust components. Conversions generally require a 3 inch or more suspension lift in order to have oil pan clearance and/or retain adequate front suspension travel.
In general, an engine can be legally swapped into a vehicle if the engine is the same year as the truck, or newer, and all stock engine emissions gear is retained. However, swap laws do vary from state to state. Before doing any swap, check your local laws to see exactly what is legal.
Also, out of Australia, Holden and Holden Special Vehicles can provide a wide array of engine options.
TOYOTA MANUAL TRANSMISSIONS
In order to use a Toyota manual transmission in a V6 or V8 engine swap, it must be of the type with a removable bellhousing. 1979 to early 1981 4 speeds and late 1983 and newer 5 speeds came with removable bell housings. There are kits available to mate any of these transmissions to a V6 or V8. However, the 4 speed transmissions and the pre 1985 5 speeds are generally too weak or problem prone to be considered for such engine swaps.
Consequently, the 1985 and newer 5 speed transmissions are the best choice if a Toyota manual transmission is to be used. Two different models have been used since 1985, one type for the 4 cylinder trucks and another for the turbo and V6 trucks. The latter unit being somewhat beefier in critical areas. Both of these models are supposedly quite strong and able to withstand sane amounts of V6 and V8 power provided a sturdy aftermarket clutch is used. However, rebuild cost for a blown 5 speed transmission is high and if you feel that you won't be able to keep your foot out of the gas, or you must run large tires, it's probably wise to consider a transmission swap as well.
Kits are available to mate Toyota manual transmissions to the Buick V6, Chevy 4.3l V6, Chevy V8s from 265 to 400 cubic inches, and Ford V8s from 260 to 351 cubic inches. These kits typically include a conversion bellhousing, clutch fork, throw-out bearing, custom clutch disk and slave cylinder to fit the new bellhousing. The stock clutch master cylinder can be retained.
NEW VENTURE MODEL 4500
The NV4500 has been used in GM and Dodge trucks since 1992. It is a five speed manual transmission that is fully synchronized in all forward gears, and also synchronized in reverse in the Dodge versions. First gear ratios have been available in 4.01:1, 5.61:1, and 6.34:1. Fifth gear ratio is 0.73:1 offering a 27% overdrive.
The transmission is very rugged having been offered in 3/4 ton full-size trucks. The main case of the transmission is built from cast iron, with some of the less critical parts made from aluminum.
Adapters are available to mate the NV4500 transmission to the Toyota transfer case. (Watch this carefully though as not all models of the NV4500 can be used with this swap.) While cost for this transmission is usually high, it is probably the one of the best manual transmissions ever made for use in a 4WD truck. The very low first gear and fifth gear overdrive combine to provide a transmission that does equally well whether crawling over rocks or screaming down the highway. And this transmission is one way to retain a manual transmission in your truck and still pump lots of V8 power through it.
GM MUNCIE 4 SPEED
The Muncie 4 speed was used in GM cars for years. Because of its strength, it is often found behind healthy V8 engines. It has also been a popular transmission because of the availability of numerous different gear ratio sets. It is possible to purchase the components to mate a Muncie to a Toyota transfer case. However, this swap does require a body lift, custom mounting and sheetmetal work, shifter linkage, clutch setup, and driveshaft modifications.
FORD T-18 FOUR SPEED
The Ford T-18 is essentially the same transmission that is so sought after by Jeep owners. It can be bolted to a bellhousing to mate to a Ford, Chevy, or AMC engine, and adapter kits are available to mate its output to a Toyota transfer case. It is a 4 speed manual transmission with a low 1st gear. This granny gear is often greater than 6:1 offering outstanding crawling capability. This transmission is also very rugged and dependable. When used behind a V6 or V8 engine, this transmission will require use of a body lift due to the large transmission case size.
BORG WARNER T-5 WORLD CLASS
Late model Camaros and Mustangs have used this 5 speed transmission combined with small block V8 power with excellent results. This transmission, while not offering a very low 1st gear (only about 4:1), offers a close ratio gear set with a short, quick shifter throw. This transmission will work well for truck applications where a granny gear is not needed. Adapter kits are available to mate this transmission to the Toyota transfer case.
DAHAITSU MANUAL TRANSMISSIONS
Mark's 4WD in Australia sells two types of heavy duty truck transmissions with adapter for use on the Toyota 4WD truck. The first is a Daihatsu truck 5 speed found in the Daihatsu Delta truck line. It offers a 5.69:1 first gear combined with a 21% overdrive gear. The second transmission is a heavy duty Toyota truck model with a 5.15:1 first gear and 17% overdrive. Both transmissions are said to adequately withstand the high loads of V8 engines and complete installation kits are available for each. As a side note, Mark's 4WD also supplies swap kits for many of the popular engines available in Australia including Mitsubishi, Holden, Commodore, and Toyota (diesel) engines. They can also perform 4 speed to 5 speed conversion on some older Toyota transmissions.
TOYOTA AUTOMATIC TRANSMISSIONS
Adapter kits have been available to mate the Aisin Warner AW4 4 speed automatic to a Chevy V6 or V8. The AW4 is an electronic shifting transmission and has been used in Toyotas, Jeep Cherokees, and Isuzu Troopers. The conversion kit consists of a replacement bellhousing to mate the AW4 to the Chevy engine and a new flywheel that accepts a torque converter from a six cylinder Jeep.
There are two drawbacks to this conversion. First, the Jeep torque converter is quite expensive, and there have been reports of numerous problems in getting the electronic shifting transmission to function properly. (This kit may no longer be available.)
GM TH350 AUTOMATIC
The three speed GM Turbo Hydromatic 350 is probably the most popular automatic transmission ever put behind a V8. It has been used in a wide variety of cars and trucks, and is readily available. These transmissions can be purchased cheaply, and there are lots of modification parts available for them. Gear ratios are: first, 2.52:1; second, 1.52:1; third 1.00:1. When doing an engine conversion, this is the easiest swap transmission to install. Note, when using a TH350 transmission on a Buick V6 it is necessary that the transmission come from a Buick, Oldsmobile, or Pontiac to provide the correct bellhousing bolt pattern.
Late model versions of the TH350 provide computer controlled torque converter lockup in 3rd gear. This action drains the torque converter of fluid and eliminates all slip to make the transmission more efficient and reduce heat. These models can be modified to provide a mechanically actuated lockup for use on non-computer engines, or in cases where the computer is not used to control the transmission.
GM TH400 AUTOMATIC
It is possible to install a TH400 three speed automatic in a Toyota truck and get the adapters needed to mate it to the stock transfer case. However, the ruggedness of the TH400 is rarely necessary in such applications. The TH400 wastes quite a bit more energy than the TH350, yet the TH350 can be made nearly as strong as a stock TH400 by replacing the sprag, and other components, and upgrading them to stronger units. Standard gear ratios are: first, 2.48:1; second, 1.48:1; third 1.00:1. One advantage to the TH400 is that there are several sets of gear ratios available for them, including a low 3.00:1 first gear.
GM 700R4 4 SPEED AUTOMATIC
The 700R4 uses a 3.06:1 first gear and has a 30% (0.70:1 4th gear ratio) overdrive. Second gear is 1.62:1 and third is 1.00:1.
In factory applications, the 700R4 uses computer control to electronically lockup the torque converter in 3rd and 4th gears. As in the late model TH350, it is possible to have the transmission built with an aftermarket mechanical lockup system. This allows lockup to engage shortly after the transmission shifts into 3rd gear and remains locked up in 4th. A TV cable runs from the carburetor or injector body to the transmission. This cable helps control upshifts and downshifts in the transmission.
Only post 1985 transmissions, or those retrofitted or rebuilt with post 1985 parts should be used. Earlier units were problematic and the high gear lockup was inconsistent and unreliable.
FORD C-4/C-5/C-6 AUTOMATICS
The Ford C-4 3 speed automatic was used for many years in Ford F-Series trucks behind small block V8s. It is a small transmission making it very desirable as far as fitting one in a tight swap situation. Gear ratios are: first, 2.46:1; second, 1.46:1; third 1.00:1.
The C-5 transmission uses a torque converter lockup similar to those found in some of the GM automatics. This transmission has been in use since the early 1980s and has been used in both Rangers and F-Series trucks. Gear ratios are the same as those used in the C-4.
The Ford C-6 3 speed automatic has been used behind both small and big block V8s. It is the high-power version of the 3 speed autos. Gear ratios are the same as those used in the C-4.
FORD AOD/E40D 4 SPEED AUTOMATICS
Ford 4 speed automatic overdrive transmissions have also been used in Rangers, F-Series trucks, and numerous cars. The AOD is the older of the two having been introduced in about 1980. The E40D begun arriving in vehicles in the late 1980s and was used behind small and big block V8s, and V6s as well. The E40D torque converter is electronically controlled and requires use of the Ford computer for shift control. Gear ratios for the Ford 4 speeds are: first, 2.40:1; second, 1.47:1; third 1.00:1; fourth, 0.67:1.
There are pros and cons to choosing either a manual or automatic transmission. A manual is generally considered to be more reliable and definitely provides better compression braking than an automatic. However, an automatic provides smoothness and ease of use, and is kinder to other drivetrain parts due to the fluid coupling as opposed to a mechanical coupling in a manual transmission. There are also installation considerations for each type when performing an engine swap.
When swapping in a non-stock manual transmission, it will be necessary to ensure that the shift mechanism fits under the floorboard and is adjusted properly, and that the shift lever is located practically in the cab. You will also need to provide an appropriate slave cylinder to operate the clutch. If the Toyota master cylinder is inadequate, it will have to be modified or replaced as well.
Installing an automatic transmission requires different modifications. In almost all cases, a cable operated shifter will be the easiest to install. A large number of aftermarket units are available. It will be necessary to provide transmission oil cooling in the radiator and also possibly in a remote oil cooler. Oil lines will have to be run to accommodate the cooler(s). A transmission kickdown or TV cable will be needed and you may have to fabricate brackets for these. It is also a good idea to incorporate the neutral safety and reverse light switches from the shifter into the wiring harness of the truck. The neutral safety switch will prevent the starter from engaging in any position except Park or Neutral. A dip stick, tube, and inspection cover will also be needed.
Homebuilt motor mounts are almost always welded to the frame. As such, you will need to remove the stock motor mounts from the truck frame. This involves cutting and grinding to get a clean rail on which to weld the new ones.
One type of custom design can be made from 2" x 3" x 3/16" steel box tubing. Mounts such as these can mate to stock GM rubber engine mounts and are welded to the truck frame. A single bolt in each mount secures the two mount halves together. Another alternative is to use aftermarket mounts that bolt to the engine block or make custom mounts, and use aftermarket urethane mating mounts. The urethane provides a firmer engine mount and remains more stable than the rubber during hard acceleration.
Once the larger engine is installed, you may find that the engine torque causes the engine to twist a bit too much on the motor mounts. There are several ways to damp or stop this unwanted action. The engine can be chained to the frame. While this method provides very sturdy support of the engine, the method is very unforgiving and will transmit driveline vibration to the frame. Another method is to adapt a small hydraulic damper between the engine and the truck frame. Such dampers can be found in late model V6 Ford Ranger trucks. This method will provide average damping of engine twist. Finally, an out-board stabilizer arm can be constructed of steel and bolted to the engine block. The other end of this arm is connected to the frame through a urethane bushing system. This method provides both tight damping control of the engine and vibration isolation from the frame.
Most often, engine swaps done on live axle Toyotas can use the Chevy V6 or V8 oil pan as is with a minimum 3 inch suspension lift. However, depending on engine position and suspension lift and travel, spring limit blocks may be required to keep the front axle from hitting the oil pan under full suspension compression. A lift is not mandatory when using the Buick V6 with a shallow pan, and may or may not be required depending on the particular Ford engine and pan used. The Ford dual sump pans seem to work well and provide the best clearance.
Trucks equipped with IFS will have oil pan clearance problems when converting to any of the V6 or V8 engines. To cure this situation, either the oil pan has to be modified extensively or a 3-4 inch suspension lift used to gain pan clearance. Modifications can be minimized by using low profile versions of the oil pans such as the Chevy Astro Van oil pan for the V6. Ford pans usually provide greater clearance and require simpler modification than the other pans. Also, it is a good idea to install heavier torsion bars when a heavier engine is installed in an IFS truck.
When a swap engine is pulled from the donor vehicle, the transmission and transfer case can be used along with it. This eliminates the need for a transmission to transfer case adapter, but has other problems associated with it. Custom driveshafts will be required. The shift lever may and may not come through the floorboard in a good location, and gaining adequate clearance between the transfer case and floorboard may be a problem. Also, since the Toyota speedometer cable originates at the transfer case, the cable will have to be adapted to the new transmission or transfer case.
Adapters are available to mate non-Toyota transmissions to the Toyota transfer case. The adapters are basically an aluminum housing that bolts to the transmission and transfer case and houses a large bearing and an internally splined conversion sleeve that mates the transmission output shaft to the transfer case input shaft. This is by far the most common swap option. Given the fact that Toyota transfer cases are very strong and reliable, this type of arrangement is well suited to almost all V6 and V8 applications. This method also allows use of the stock Toyota driveshaft ends and retains the stock speedometer cable.
There is also an adapter available to mate the Toyota 5 speed to a Dana 300 transfer case which offers a 2.6:1 low range ratio.
Installing another engine may require that the transfer case be relocated back a few inches. In a few cases, it may be possible to move the entire transfer case crossmember back and fabricate new mounts on the frame. However, it is usually much easier to leave the crossmember in the original position and resecure the transfer case to the crossmember using an extension plate.
Bolt-on repositioning plates are available for this purpose, or a plate can be fabricated and bolted or welded into place. One means of doing this is to fabricate a custom cross-member extension from 6" x 2" steel channel that is notched and welded to the cross-member. The relocated transfer case can then be bolted to this extension piece.
Driveshafts can usually be shortened and rebalanced for about $40 or so. Lengthening is a bit more expensive because the entire main tube has to be replaced. This will usually run about $70-90.
One specific driveshaft case deserves mention. Whenever the GM 700R4 auto transmission is used, a new driveshaft made of smaller diameter tubing is required in order to provide clearance between the driveshaft and transmission pan. The 700R4 transmission does not have a corner notched pan like the TH350 transmission. Be sure that there is adequate clearance between the front driveshaft and transmission oil pan on any conversion.
There are several aftermarket conversion headers available to solve this problem. One type, referred to as a Slick-Fit, is a compact design that fits very close to the engine and uses rear dump collectors on each side. The exhaust port runners dump immediately into a collector at rear most cylinder.
Other aftermarket headers are available that are longer and generally use a 3-into-1 or 4-into-1 design. These headers use long primary runners that converge into a collector between the frame rails to the sides of the transmission.
One other option is to use modified factory Chevy headers on the swap. Over the years, several GM vehicles have used factory tubular headers on V6 and V8 engines. These tubular manifolds can be modified to clear the truck frame rails. This involves removing the end flanges and lengthening the tubing sections before reattaching the flanges further down past the frame rails.
Fuel injected engines that require use of an oxygen sensor will need to have a threaded fitting installed in the proper place in the exhaust tubing. These are placed in either one or both legs of the Y-pipe, or further past the Y-pipe junction. An original application for the engine should be studied and the conversion installation should duplicate the sensor position as close as possible. Note that changes in other exhaust components in the system can affect performance of the oxygen sensor.
One alternative that is rather expensive but provides an excellent radiator that bolts right in the truck is to buy one of the special design radiators offered by one of the aftermarket companies. These units bolt right up to the stock mounting holes and are well constructed heavy-duty copper units that provide excellent cooling. There is one drawback to some of these though. The radiators hang low on the truck requiring fabrication of a steel guard for protection. A guard can be made from steel angle to protect the lower portion of the radiator.
If necessary, there is wide variety of water necks that can be purchased for the various engines. There are ones available with additional threaded outlets for plumbing heater lines if needed. Check the catalogs at your local auto parts store for the different water neck styles.
Most V6 and V8 engines have water pumps available in both short and long varieties. Changing from a long type to a short one may provide the fan or radiator clearance you need. A short pump is always required on V8 conversions.
A stock-type clutch fan provides the best cooling, good efficiency, and excellent reliability. Its blades are fixed pitch and provide considerable airflow when turning. The thermo clutch unit turns the fan on or off depending on engine temperature. This helps maintain the engine at a constant temperature and helps relieve extra load from the engine. Unfortunately, clutch fans almost always require alot of depth due to their fan pitch and shaft design.
Flex fans maintain a sharp pitch at low rpm to provide lots of airflow, but flatten out as rpm rises to help keep an even airflow going and relieve some load from the engine. They are always turning and constantly place some load on the engine. Flex fans usually provide less cooling ability than the other types, but have the important advantage of being fairly thin and not requiring much mounting depth.
Electric fans come in a variety of sizes and styles, and can be thermostatically controlled to turn on and off with changes of engine temperature. They have the advantage of being mounted either in front of or behind the radiator, and as such, are the most versatile of the fan types. Electric fans are a popular choice for V8 conversions. Where space is tight, two small fans can be used in place of one larger one. The one downside is that electric fans may be the least reliable. Also, don't assume since they are electric, you get something for free. The fan pulls power from the electrical system and the engine must still turn the alternator to provide power to the battery.
If using a mechanical fan, fan spacers may be required to locate the fan out to clear the front of the engine and belts. These are available in all sizes, typically in 1/2 inch increments.
Electric power for the fuel pump in most EFI systems is supplied via the engine harness. It is also a good idea to add a large canister type fuel filter spliced in-line.
A word of caution when using electric fuel pumps is in order. Factory equipped fuel injected vehicles always incorporate a safety circuit to turn off the electric fuel pump any time the engine stalls. This is to prevent fire in case a fuel line were to burst. The engine will stall, but without such a circuit, the pump would continue to spray gas into the engine compartment.
The fuel pump circuit generally works as follows. When the ignition switch is turned to the start position, the fuel pump is energized directly (possibly through a relay) by this switch. Once the ignition switch is released to the run position, the fuel pump is energized only if has an indication that the engine is actually running. This signal is provided by the airflow meter on a Toyota engine or sometimes by an ignition signal on other engines. If this signal is not present, the circuit assumes the engine is not running and turns the fuel pump off. When adding an electric fuel pump in an engine swap, it is a good idea to provide such a safety circuit for the fuel system.
The new alternator can be spliced into part of the original Toyota wiring. The following description gives a general procedure for wiring up the new alternator. Specific wiring details will vary with the alternator being used and the particular year model of the truck.
The B+ terminal of the alternator is connected to the large wire in the Toyota harness or connected directly to the positive battery post using a 6 or 8 gauge wire. The case of the alternator is grounded using the original black Toyota wire. The terminals on the alternator are connected to the white (+) and yellow (charge) wires in the Toyota harness. Again these may vary with the specific swap parts.
Once the swap is complete, ensure that the battery used in the truck has sufficient capacity to easily crank over the bigger engine you've installed.
The GM and Ford power steering pumps use an integral reservoir mounted to the back of the pump. Since one of these is already mounted to your new engine and the belt system has been done for you, it is usually easier to use this instead of the original pump.
To adapt the pump to the Toyota steering box, simply run new power steering hose to plumb the low pressure side of the pump. For the high pressure side it is usually best to use the stock hose that came on the engine. This will route correctly between the pump and the engine. Shorten it as needed by cutting a portion of the steel tube end off. Replacing the tubing flare nut on the pump end with the one from the original Toyota hose, and reflare the tube end. If you cannot flare the tube end to fit the pump, hose adapters are also available to make the connector conversion. The original power steering cooler can be retained behind the grille and standard power steering fluid can be used in the system.
When using a harness from the donor vehicle, it will be necessary to carefully separate the portions of the harness that are engine related form those that are not. This can be a long and tedious process, but it can be done. A simpler, yet more expensive solution, is to purchase a harness made specifically for the engine swap you are doing. These harnesses are well made, many times using the same components as GM and Ford. The advantage is that they are made fresh without all the non-engine wiring. They are easy to use and provide a clean, professional appearance. Also, you do not have to worry with wiring gremlins when you have so much else to do during the conversion.
One item that is never mentioned in most Toyota swap info is that the ignition switched solenoid line on Toyota trucks cannot source sufficient current to reliably engage some domestic starter solenoids. Therefore, it is necessary to wire the solenoid line to a relay and provide a switched V+ line from the battery through the relay. Use the original Toyota ignition signal to energize the relay. Voltage can be supplied to the new ignition coil via the original Toyota harness wire.
There are two ways to cure the problem and have a tachometer display actual rpm. One is to buy an aftermarket tachometer, and two is to recalibrate the stock one.
The Toyota tachometer accepts the pulsed ignition signal from the coil and converts it into a proportional DC signal that drives an analog current meter in the dash to display engine RPM. Its reading can be scaled to correctly display the correct engine RPM by adding a calibrated resistive shunt to the meter input.
A 5k ohm trim potentiometer is placed across the input contacts to the tachometer meter. This is done directly at the meter posts inside the instrument cluster. For this purpose, it is best to use a small 10 turn potentiometer to provide easier calibration of the tachometer. This potentiometer can be purchased at almost any electronics store. Solder wires to potentiometer and find a way to add it to the wiring at the back of the meter. The figure below shows schematically how this is done.
Once installed you will be able to recalibrate, or scale, the tachometer reading by adjusting the potentiometer. By running the engine and using another accurate tachometer as a reference, adjust the potentiometer until the engine RPM readings are both the same. You now have a factory tachometer that reads accurately for your V6 or V8 engine.
For Toyota trucks that were not originally equipped with such a dash light, a simple 12V light installed in the dash will work. Trucks that were originally equipped with the light can use the signal from the new engine by splicing into the wire in the Toyota harness.
Once complete, it is a good idea to ensure the cable operates smoothly through its entire range, and that you truly get full throttle opening when the pedal is pushed to the floor. Depending on the carburetor or injector unit used, you may have to shorten or lengthen the throttle lever to dial in just the right ratio to match the movement of the Toyota pedal assembly.
When switching to an automatic transmission, the clutch pedal is often removed. This may trip the clutch switch that disables the cruise control. To restore its function, it will be necessary to either electrically override the function or mechanically disable the switch.
Brackets are available to allow mounting of the stock Toyota air conditioning compressor to GM engines and brackets should soon be available for the Ford engines as well. Some engines may require that you fabricate your own custom bracketry. By reusing the stock Toyota compressor, all cooling lines and electrical wiring can remain unmodified. With care, you can even install the new engine without ever leaking the a/c system.
Many times it is easier to use the air conditioning compressor that came with the new engine. This is especially true when using an engine with a serpentine belt. While the compressors on such an engine usually rotate in the same direction as one on a non-serpentine belt engine, retrofitting a stock Toyota compressor will require somehow changing the pulley to one that can accept the serpentine belt.
If a different compressor is used, it will be necessary to modify the hoses to mate the compressor to the rest of the system. This will require making custom a/c hoses. One way to do this is to use compressor fittings, and possibly some of the hose, that comes with the new compressor and mate these to some of the original Toyota lines. The metal end of the hose that attaches to the condenser at the front grill can be cut and mated to the high pressure compressor line. The low pressure hose can be adapted as well by using the metal end of the original hose that meets at the firewall.
A competent repair shop can mate the hose pieces for you using high pressure crimp connectors. Depending on the compressor used, you may also need to install inline charging and suction valves as the originals were mounted to the Toyota compressor. In some cases using GM compressors, where a metal tubing header is used on the compressor, the header may not route the hoses well in the Toyota engine compartment. There is a variety of these headers available in all shapes and sizes. Also, it is possible to have a shop cut and rotate the tube outlets to face in the proper direction.
The original Toyota electrical connector that hooks to the compressor is a single conductor and provides a 12V signal to actuate the magnetic clutch and turn on the compressor. The appropriate GM or Ford connector can be spliced into this wiring to hookup the new compressor. Most of these connectors are two conductor, one the 12V signal and the other ground. The ground wire from the connector can be attached to a bolt on the new compressor.
The new compressor should work fine on the Toyota system. An a/c compressor is essentially a dumb device. It pumps when it is told to and is either on or off. The a/c control circuit is responsible for telling the compressor when to turn on and off. In the Toyota, this is done by the a/c amplifier, a circuit that monitors certain sensors in the system and decides how to control the compressor.
One function of the a/c amplifier is to monitor engine rpm and turn off the compressor as engine idle drops below about 600-700 rpm to prevent the engine from stalling. The speed at which this unit cuts out is often adjustable at the a/c amplifier under the dash. When a new engine is installed, it is necessary to retain the tach input to the a/c amplifier to allow it to turn on the compressor. However, with a V6 or V8 the engine rpm will be 1.5 to 2 times higher for a given rpm and the compressor will probably never turn off due to low idle speed.