Dodge M37 Small Block Chevy Engine Swap Tips - 4-Wheel & Off-Road Magazine

Dodge M37 Gmc Engine Swap Drop In Engine

We got this complete 6.0L engine out of an '04 GMC Denali from Pacific Fabrication. Though the engine was used, we deduced that it probably had under 65,000 miles. When new, this engine (also known as an LQ4) produced around 325 hp and 365 lb-ft, so even with some miles it should still smoke the tires.

We got this complete 6.0L engine out of an '04 GMC Denali from Pacific Fabrication. Though

There are lots of engines available to stuff in your 4x4, but the small-block Chevy has never been surpassed as the hottest engine swap ever. With the Generation III and IV engines (aka LS Series) flooding the used and crate engine market, they are quickly replacing the old standby small-block GM as the easy engine to swap due to their ability to produce cheap, reliable, fuel-injected power.

We did a buildup on an LS-style engine in Aug. '08 ("Lego Engines"), and now it's time to stuff one under the hood of a truck. The old Dodge M37 military truck you see here is one of the next wheeling rigs we'll be building. There will be more info on it in the future, but for now we'll just touch on things to remember when swapping any engine in your 4x4. (Oh, and before you Dodge guys get all bent out of shape over our putting a GM in a Dodge, let us tell you that we saved this truck from the crusher; it had no engine when we found it and the used GMC 6.0L V-8 was a deal we couldn't pass up.)

Dodge M37 Gmc Engine Swap Exhaust Manifolds

Note the front differential at full suspension compression, as well as driveshaft, steering, exhaust, transmission and transfer case clearance, the fan-to-radiator spacing, and the ability to get to the engine for any maintenance. Offsetting the engine an inch or two for clearance and angling the back down a few degrees (we went to 4 degrees) isn't uncommon. We swapped out the standard truck exhaust manifolds for these tighter-fitting F-body manifolds and are using the rear sump truck oil pan.

Before you perform an engine swap it's good to go at the truck with a hose and a tape measure. We spent a couple days cutting, grinding, and pressure-washing the engine bay before we got the engine anywhere near it. Once all the old motor mounts, plumbing, wiring, and ancillary junk was removed we swung the engine into place and started measuring for engine mounts.
Before you perform an engine swap it's good to go at the truck with a hose and a tape meas
We made simple 1/4-inch steel motor mounts that use a bushing and a sleeve to support the engine. Though drawn up on a computer and cut out with a plasma table there is no reason why cardboard templates and a torch and grinder couldn't be used to make these if you take your time. Never ever ever weld the motor mounts in completely until you are 200-percent sure they are in the correct location.
We made simple 1/4-inch steel motor mounts that use a bushing and a sleeve to support the
Pacific Fabrication offers a simple and clean wiring harness for Gen III and IV engines that utilizes the factory computer (powertrain control module, PCM) in addition to complete engines ready to run. Pacific's harness can even run cruise control, a factory gauge cluster, and an electronic automatic transmission like a 4L60E or 4L80E.
Pacific Fabrication offers a simple and clean wiring harness for Gen III and IV engines th

The Pacific harness also uses a drive-by-wire throttle pedal. We were apprehensive about this at first, but feel it will actually make installation much easier and should still drive as good as or better than with a throttle cable.
The Pacific harness also uses a drive-by-wire throttle pedal. We were apprehensive about t
Plumbing late-model GM V-8s has also gotten easier with Russell Performance's new Universal EFI plumbing kit for GM-LS series and late-model Dodge Hemi V-8 engines.
Plumbing late-model GM V-8s has also gotten easier with Russell Performance's new Universa
The Edelbrock electric fuel pump delivers roughly 60 gph and has adapter fittings for A/N-style hose ends. We mounted the pump safely inside the rear framerails below the fuel tank, but after a fuel filter to keep it constantly fed with clean gas.
The Edelbrock electric fuel pump delivers roughly 60 gph and has adapter fittings for A/N-

The Pacific harness can be built stripped down to require just a keyed 12V input such as we need for our manual-transmission, mechanical-gauge, no-A/C truck. All wires are clearly labeled and either plug into the engine sensors or run to the fuel pump, oxygen (O2) sensors, a "check engine" light, or battery. Unlike other aftermarket harnesses the Pacific kit uses dual O2 sensors to adjust engine management under heavy load and in higher elevation.
The Pacific harness can be built stripped down to require just a keyed 12V input such as w
The kit uses a late-model GM-style fuel filter/regulator that mounts between the fuel pump and the engine. It has an inlet (red cap) and a return (orange cap) on the feed side and then flows out through a special push-in adapter fittings to the A/N-style hose ends. We protected the black Pro Classic fuel line from heat and chaffing with some orange Russell coated heat shield.
The kit uses a late-model GM-style fuel filter/regulator that mounts between the fuel pump
The adapters from -6 A/N hose ends to the OEM push-on-style fittings are the family jewels of this kit. Both the fuel filter/regulator and the engine's fuel rails require these special adapters. Russell engineers developed them to easily plumb leak-free from any A/N-fitting-equipped fuel tank to the late-model GM and Dodge V-8s.
The adapters from -6 A/N hose ends to the OEM push-on-style fittings are the family jewels

A V-8 in a Jeep?!
Folks have been putting V-8s in Jeeps and Toyotas for ages, and Advance Adapters has been there every step of the way. We went to Advance for the bellhousing, clutch, and flywheel for our Gen III engine in our old Dodge project, but the company also offers a full line of parts to stuff almost any era of GM V-8 into a CJ, Wrangler, or Land Cruiser, such as motor mounts, exhaust headers, and adapters. We wouldn't be surprised if Advance also has a kit for the Gen III and IV V-8s in a new JK Wrangler before too long.

SOURCES
Advance Adapters 4320 Aerotech Center Way P.O. Box 247 Paso Robles CA 93446 805-238-7000	Russell Performance 2301 Dominguez Wy Torrance CA 90503
Pacific Fabrication www.pacificfab.net