target="_blank" rel="nofollow" href="#fb3_img_img_29698016-214c-5ef3-add7-f2400a9fdca3.jpg" alt=""/>
The key to any swap is getting the engine into the chassis. This can be easy or it can take weeks to figure out, it all depends on the car. The 1968–1972 A-Body vehicles are easily converted to Chevy small-block frame mounts, but the earlier 1964–1967 A-Body cars are not as simple. General Motors certainly helped swappers by using the same motor mount design for all Gen III/IV engines, except the LS4, which is a front-wheel-drive platform. The LS-series engines share a footprint similar to the classic Chevy small-block engine’s, so they fit in virtually any chassis that can house a Chevy small-block. That’s a significant advantage to the swapper, as the conversion from a Chevy small-block to an LS can be as simple as adapter motor mounts.
The LS motor mount uses a four-bolt mount that bolts to the side of the engine block. This is not directly compatible with the standard three-bolt Chevy small-block mount. The most common solution for this change is converting the LS engine to the more usual early-style three-bolt engine mounts.
The original Chevy Gen I small-block from 1955 featured the three-bolt motor mount configuration, and the same motor mount pattern continued in production through the second-generation small-block, the LT1 and LT4. However, these engines are not to be confused with the new-generation 2014–up LT1 Gen V series. (Yes, General Motors reuses its nomenclature and it can be very confusing.)
Bolting the adapters to the engine is simple: four socket head bolts and you are done. Make sure you use some anti-seize compound to prevent galling of the different metals.
Numerous companies make adapter plates to convert the LS mount to accept a Chevy small-block three-bolt mount. With so many adapters (hundreds of different brands are available), deciding which to use is the tough part.
When compared to the Chevy Gen I/II small-block, the stock LS engine motor mounts are located farther back toward the bellhousing. If a motor mount is bolted to the frame using these holes, in most vehicles the engine sits too far forward. This increases the nose weight of the car, causing instability.
Some adapter mounts are for specific applications, such as the Holley mounts for GM A-Body cars. In addition, universal adapters are available with offset mount locations, such as 1.25 inch forward and .5 inch up, to better facilitate engine placement for chassis and body clearance. Dirty Dingo offers adjustable adapter plates, so you can get the positioning just right for your application.
Simple adapter plates are a common solution for many LS swaps’ engine mounts. These plates from Hooker are made of billet aluminum. They bolt to the Gen III/IV four-bolt engine mount pad and allow a three-bolt GM motor mount to bolt on.
Not all adapters are the same. This kit from ATS flips the Chevy small-block mounts upside down to set the engine lower in the chassis. These are designed to fit the first-generation Camaro and the GM A-Body.
Simply bolting the adapter plate to the engine block provides mounting provisions for the old-style Chevy small-block three-bolt engine mount. This allows the LS-series engine to essentially drop right into the chassis without much effort.
For yet another alternative, American Touring Specialties (ATS) offers a set of LS adapter plates that feature an early-style motor mount in an upside-down configuration. ATS offers this arrangement so the engine can sit lower in the car and farther back toward the firewall, for better stability and a lower center of gravity. With these ATS mounts, an LS engine can be swapped into most any GM A-Body.
Depending on the motor mount, certain interference issues may occur, most commonly, oil pan to crossmember and ground clearance, passenger-side valvecover to air conditioning compressor, and transmission bellhousing to transmission tunnel clearance.
Some adapters, such as these Trans-Dapt mounts, require a lock nut on the back side of the plate. The external webbing makes it a bit of a pain to install the lock nuts, but these nuts are recommended to add extra security.
Opinions vary as to which adapter style is the best fit for 1964–1972 A-Body platforms. The reality is that it depends on your engine, transmission, and component combination. This time frame in GM’s history was the beginning of using corporate parts throughout the GM brands.
Before 1964, GM nameplates Cadillac, Chevy, Buick, and Oldsmobile manufactured and installed parts unique to their respective models; as a result, only a few components were shared across brands. In most cases, the chassis platform shared the frame or unibody structure, but very little else. In 1964 this changed, and suddenly GM brands were using “corporate” parts that interchanged between platforms, starting with suspension components and transmissions.
Engines, however, were still brand-specific. Although this does create a bit of a headache, the nice thing for 1968–1972 A-Body builders is that all the frames are drilled for every engine stand. You can easily bolt a Chevelle engine stand into a Buick, Oldsmobile, or Pontiac frame.
Once the locking nut is on the back-side, you tighten the bolt in the plate (which is also threaded) and then tighten the lock nut. If your adapter plates require nuts, you can use a box wrench with a tap on one side to hold the nut in place while you install it.
Converting
