One of the best things about building a classic truck is the ability to shoehorn just about any production powerplant between the framerails with room to spare and plenty of hood clearance. By their very nature, trucks are wide and boxy, which yields a fairly massive engine compartment that can accept anything from a late-model Ford Mod motor like fellow staffer Grant Peterson's Bumpside Build-Off Ford, or a vintage Chrysler Hemi, which we're dropping in my '52 Ford F-1 project. The point is, the sky's the limit when it comes to power options for most vintage trucks, so sticking in a cookie-cutter, small-block Chevy because "it's easy" just isn't a good excuse. And while the roominess found under the hood of most classic trucks helps make the job of swapping engines quite a bit easier than shoehorning a big-block into a Pinto, the same basic theories apply to both applications.
The first decision to be made is where to put the engine. Obviously, most of us aren't going to be sticking the thing in the bed, so suffice it to say it's going where it belongs-in the engine compartment. But placement in relation to other items under the hood is what we're talking about. Bound by the firewall to the rear, the radiator to the front, and flanked by a pair of hood sides, the location of the engine is more or less determined with only a few inches of "fudge." A balancing act of sorts must be performed to get the engine clear of the firewall and still have enough room between the block and the radiator for the water pump, pulleys, fan, and so on. While moving the engine rearward means a benefit in handling as more weight is transferred to the rear wheels, the need to cut into the firewall to clear the distributor or bellhousing and the intrusion into the passenger compartment usually makes this a last-ditch choice. A better option is to use an aftermarket radiator that can be mounted ahead of the stock radiator mount, resulting in a gain of a few inches if necessary. More often than not though, with a little finessing, most V-8s will fit within the stock confines.
But simply shoe-horning a motor so it fits between the radiator and the firewall is just the beginning. The engine also needs to be centered, level, with correct pinion angle, oil pan, and ground clearance. Meeting these stipulations is rather simple, provided careful planning and forethought is taken. What you don't want to end up with is a setup where the drag link hits the oil pan, or the pulley is so close to the crossmember that you can't get a belt on correctly. You may snicker, but we've seen way too many examples of this.
If you study a car built by one of the many professional shops across the country, what you may find is that the engine actually appears slightly high on the chassis. This is done for two reasons. One, to keep clearance between the oil pan, drag link, suspension crossmember, and the ground at a maximum. And two, to place the cooling fan in the center of the radiator, where it's going to move the most air efficiently through the radiator without making any hot spots at the top or bottom. This is a commonly overlooked aspect of setting an engine up. With the motor low in the chassis, the fan may only cover 65 percent of the actual radiator core, resulting in a hot spot due to an area of stagnant airflow towards the top. The subsequent over-heating tendency of a motor in this situation may drive the owner to install an electric fan in front of the radiator to help cool the motor, further cutting off the airflow through the radiator and ultimately making matters worse. For most properly setup street engines, a mechanical fan should be sufficient in all but the most demanding environments.
Although some Detroit manufacturers will offset the motor, it's really ideal and more aesthetically appealing to center it in the chassis. A few measurements from each framerail to the crankshaft centerline in the front, and each framerail to the output shaft on the trans in the rear will get the motor centered. It also wouldn't hurt at this point to make sure the chassis, as well as the engine, is level.
If there's a rearend already installed in the truck, now would be the time to check the pinion angle. The relationship between the pinion angle on the input shaft of the rearend and the output shaft of the transmission needs to in sync. That is, if the rearend measures 5-degrees up pinion angle, the drivetrain should be set up with 5-degrees down. This will ensure that the harmonic and mechanical vibrations that naturally occur in the driveshaft as the universals spin and the rear suspension travels through its arc, will not be transmitted throughout the vehicle. If the rearend has yet to be installed, refer to the manufactures specs for whatever rear suspension components are to be used. The 5-degrees up is a commonly used spec, Total Cost Involved, for example.
Getting the motor to fit under the hood and squaring everything up is just the beginning though, as mounts need to be sorted to support the engine and trans. For common Chevy, Ford, and even Chrysler engines, there's a whole slew of companies that design motor mounts specifically for each application, small-block Chevy in a '56 Ford pickup for example. But for some, such as our Hemi power plant in our F-1, we were stuck using a universal mount from Chassis Engineering. Because of the fact that we installed a Heidt's IFS frontend and were using an uncommon engine, there's no way for a company to make a specific motor mount kit. This is one example of where putting an oddball mix of parts together can be both challenging and rewarding. To get the CE mounts to fit our chassis, a little bit of trimming was necessary, but with the engine sitting exactly where it needed to be, the lower mounts were simply trimmed until they met the upper mount and were then tacked to the frame. Mounting the T5 transmission was even easier, as it was already mated to the Hemi with a Wilcap adapter and supported by a floor jack at the correct pinion angle. Since we're going to be installing a Total Cost Involved pedal assembly, we're using their trans crossmember, which simply bolts to the lower frame flange.
Since our F-1 most likely had a six-cylinder installed originally, dropping any V-8 engine between the framerails would have basically been the same amount of work as installing the Hemi/T5 combo. But instead of having a standard, cookie-cutter small-block powered Ford, we've now got a vintage combo that will not only turn heads, but will perform just as good as any of them new crate engines!
 With the motor and trans in...  With the motor and trans in place between the framerails, the first thing to do is to make sure the chassis is level. Take a few readings, from the front crossmember, to the area where the trans crossmember will be, and back towards the rear crossmember to ensure the chassis isn't twisted on the jackstands. |  The next step is to ensure...  The next step is to ensure that the engine is level as well. With the block supported by the front crossmember, each side can be shimmed until it's perfectly level... |  ...Note that the upper Chassis...  ...Note that the upper Chassis Engineering motor mounts have been attached to the block; the lower mounts will get weldedto the chassis a little later. |