Motor swaps can turn into a can of worms the size of the Stay Puft Marshmallow Man if you're not prepared to overcome all of the hurdles that get in the way of droppin' a new mill into your older ride. Some swaps are easier than others, but no matter what type of engine you're swappin', there are a few steps you'll have to perform. This is a primer on the areas of your truck that will need to be modified in order for that new engine to come alive once you've situated it between the fenders of your sport truck.
We've included a short list of suppliers that offer everything we've talked about in this story. These companies are also able to guide you through your swap with in-depth technical knowledge. What you can't find here can be located on the Internet using a web search application.
Mounting
The popular swaps are easier because there are companies out there that build conversion mounts for the engine and transmission. The odds are good that whatever engine you are replacing is longer, shorter, wider, or narrower than the new one. The same goes for the transmission. Even if you keep your current transmission intact, the mounting location will change based on length of the engine and motor mount locations on the block, and that will require a new tranny mount or relocating the existing one.
Fitment
If your goal is to stuff a small-block into a Chevrolet S-10 then you're in luck because it fits with very little trimming. If you fancy a big-block in that same truck, then get out your big saw because that's going to require more cutting. Some truck and engine combos can require firewall and transmission tunnel surgery. And, if you've got a really big engine, the valve covers can interfere with the power brake booster and/or air conditioning system.
Exhaust
Most of your truck's exhaust system will need to be scrapped from the middle of the cab forward. Conversion headers are your best friend here because they will usually route the collectors away from the framerails and steering components, leaving you room to build a new set of downpipes.
Wiring
Companies like Painless Performance build custom wiring harnesses that make connecting popular engines like GM's LS1 to your truck's subsystems a snap. If you can't find a custom harness for your application then label every wire you remove from your old engine before you remove it. That will be your best shot of getting the new motor hooked up after the swap is complete.
Plumbing
Some engine swaps involve upgrading a carbureted engine for a fuel-injected one. This opens another can of worms involving plumbing. You'll need a high-pressure fuel pump and regulator designed for fuel-injection and a proper return line. Additionally, don't forget that the new engine probably has different connections for the water pump and radiator. Custom radiator hoses like the ones offered by Cool Flex make raiding your local parts house's hose bin a headache you don't have to endure.
Cooling
If you're trading a four-cylinder engine for a V-8 then plan on trading up to a larger-capacity radiator as well. The cylinder pressures of a V-8 are greater, creating more heat and requiring a cooling system that can keep engine temperatures in check. Plus, if you go with an aftermarket aluminum radiator, not only do you get a better-looking piece, but many companies like Griffin and Flex-a-Lite will custom build it to your specifications. This makes placing the inlet and outlets and trans cooler lines in the right spot a snap.
Driveline
The odds are good that you'll need a new driveline to complete your swap, or at the very least you'll need to shorten the one you already have. This is a great time to look into upgrading your U-joints to larger and stronger ones. You racers can also purchase an aluminum or carbon-fiber driveline if weight is a concern and money is no object.
Accessories
If you're missing parts to mount an alternator or air conditioning compressor to go with your new engine, don't worry. Besides the junkyards that might have what you're looking for, there are also aftermarket companies building shiny, new parts as well. For example, Street and Performance builds a bitchin line of serpentine belt accessory systems for old and new small-and big-block Chevy engines. You'll also want to look to companies like Lokar to hook up your shifter to that new tranny if you've gone that far with the swap as well. Also, don't forget that if your donor engine came from a car or another truck model that you might need a new oil pan with a sump in the right location for your truck. Hamburger's, Milodon, Street and Performance, and Moroso are excellent sources for new oil pans.
Steering
If the engine swap you have in mind is aimed squarely at increasing your truck's performance, then don't forget to give your steering system a once-over. Swapping from a column to floor shifter is a mod that can be accentuated with a slick new steering column from Iditit.