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How To Assemble Hooker LS And LT Clamshell Motor Mounts for an LS or LT Swap

Author: Jefferson Bryant | 07/08/2021 < Back to Motor Life Home
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Swapping an LS or Gen V LT engine into your vehicle of choice used to take months, now it can be done in a weekend. One of the trickiest components to any engine swap are the engine mounts themselves. This is the starting point for every other component that you will use, and if the engine is set too far forward or too far back, you will find interference issues that you never even knew were possible. I once swapped an engine, built a turbo system, transmission mount, the works, only to find out at the last minute that the engine was set too far forward and no sway bar on the planet would clear the oil pan. Oops.


Getting the mounts right is critical, and these days you have a lot of options. Most engine mount kits use basic adapter plates to shift the engine forward or rearward X inches, so you either have to already know where your engine needs to go or you have to guess and take a risk that you will have to buy other parts to get it right. Selecting a swap system, such as the Hooker Blackheart LS/LT swap kits, is much simpler. Hooker has already done the math and the fabrication to ensure that when used with their other swap components, your engine will sit exactly where it needs to.


One of the key differences with the Hooker system are the motor mounts themselves. Unlike other adapters, the Hooker Blackheart mounts use GM 4th-gen F-body LS engine mounts instead of relying on the older Gen 1 SBC mounts. This means that your motor mounts bolt right onto the block as they were originally intended. You are not bolting on an adapter plate, which often do not fit correctly and tend to cause issues with clearance because there are different SBC mounts that may or may not fit the adapter itself.


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For our 1966 Suburban, we selected are using the Hooker Blackheart frame stands, which simply replace the factory frame stands. Which is a good thing, as our GMC came with the rare 305 cubic inch V6, and we would have had to source frame stands otherwise.


Using the clamshell mount also greatly simplifies the bolt-in process. The factory rubber isolator block has locator tabs that sit down onto the frame stands, making the tedious task of adjusting the angle of the engine much easier with a visible guide and it helps keep you from moving too far. Engine swaps rarely just drop in, but with these mounts, it took us about 10 minutes to get the engine bolted in once it was set on the stands.


There are a couple of key points you need to know when assembling the clamshell mounts. Those metal tabs must be toward the top of the block. If you flip them upside down, the engine will not sit into the frame stands. The isolator also has raised blocks on the front and back that lock the isolator into the clamshell, you need to make sure these are oriented correctly.


We preassembled our engine mounts before doing anything else to our LS engine. The simplicity of these mounts really makes the process of bolting an LS or LT into your vehicle a couple hour job. When you use these mounts, all of the Holley and Hooker LS/LT swap components become bolt-ons, including transmission mounts, headers, exhaust, oil pan (required with these mounts), and even the accessory drive. It just doesn’t get much easier.


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The inner side of the isolators have 4 ribs, like a chocolate bar. These fit into the indentations on the inner engine block half of the clamshell.


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On the outer half, there are two large blocks that seat into the outer clamshell. You can’t really put this together backwards, but you can install the isolator upside down, so pay attention.


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There is a top and bottom to the clamshell. The raised center section is the top as shown here. We marked the table to that we wouldn’t get them upside down during the assembly.


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The top is critical because the isolators have tabs on the sides that locate the engine to the frame stand, these tabs MUST be at the top of the clamshell.


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We pre-installed the supplied bolts into the inner plate, and dropped the isolator onto the plate, being careful to locate the tabs correctly.


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Then we used a 13mm wrench and 13mm socket to secure the outer plate to the lower. We used an adjustable impact gun set to stun (wrench tight, which is 24 ft-lbs. on our tool).


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Here you can see the correct orientation of the tabs to the frame stands. This tab is really handy for aligning the engine into the chassis.


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Next, we bolted the assembled clamshells to the engine block. This requires the original bolts, so if you don’t have the originals, you will need to source the, these bolts are M10x1.5x20mm, you need 8. These bolts have a 15mm socket head, and were torqued to 37 ft-lbs. on the iron block, 25 for aluminum blocks.


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Once the engine was dropped into the chassis, you can see how the tabs help as a guide to adjust the engine. A little gentle prying with a long crow bar helped to align the bolts.


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We opted to slide the supplied bolts back to front so the nut would be more easily accessible. The through bolt get torqued to 70 ft-lbs.

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