For classic car enthusiasts, the allure of vintage American muscle is undeniable. However, blending vintage style with modern performance and technology is a growing trend. If you’re a Mopar aficionado with a vision for enhanced power and driveability, especially if you’re dreaming of injecting modern tech into a ’68 Plymouth GTX or similar B-body classic, then diving into a Gen III Hemi swap might be your ultimate project. This guide details a journey of upgrading a ’69 Plymouth Satellite with a 5.7L Hemi and explores considerations for OBD2 integration, relevant for anyone contemplating a similar modernization of a ’68 Plymouth GTX.
Alt text: A detailed view into the engine bay of a classic Mopar during a Hemi engine swap, highlighting the integration of a modern engine into a vintage chassis.
This project started with a ’69 Satellite, a car purchased after a decade of storage. Originally equipped with a 318ci engine, 904 transmission, and column shift, this B-body Mopar, while solid, was ripe for modernization. Though technically a Satellite, the front clip had been previously swapped with a ’69 Coronet front end – a detail that often sparks conversation at car shows. Factor in some cosmetic quirks like a bumble bee stripe that wasn’t quite right, and it became clear this car was the perfect canvas for a significant upgrade. The goal? To inject modern Hemi power while retaining the classic Mopar charm. This experience translates directly to considerations for models like the ’68 Plymouth GTX, especially when thinking about incorporating modern engine management systems and potentially OBD2 diagnostics.
Alt text: Close-up of a Gen III Hemi engine being installed, showcasing the modern powerplant destined for a classic Mopar chassis during an engine swap project.
Researching Your Hemi Swap and OBD2 Options for Classic Mopars
Embarking on a Hemi swap into a classic Mopar like a ’68 Plymouth GTX or a B-body Satellite requires careful planning. One of the initial hurdles is navigating the choices for engine, transmission, and the crucial engine control systems. For those prioritizing reliability and simplified integration, opting for new components can significantly streamline the process. In this build, the decision was made to utilize all-new parts, minimizing compatibility issues and potential startup headaches.
Instead of sourcing a used engine, a Mopar Performance 5.7L Crate Engine was selected, complete with a factory controller and wiring harness. Complementing the modern engine, a new A727 TCI transmission was chosen to replace the original 904. For anyone aiming for OBD2 functionality in their classic Mopar, especially a ’68 Plymouth GTX, understanding the engine management system is key. Modern Hemi crate engines often come with their own ECU (Engine Control Unit) which is OBD2 compliant. This is a significant advantage, allowing for modern diagnostics and tuning capabilities.
To ensure a seamless fit into the classic B-body chassis, Holley B Body Gen 3 Hemi Swap components were extensively used. Holley offers a comprehensive range of parts specifically designed for this type of swap, simplifying everything from engine mounts to exhaust systems. The Holley components ensured excellent fitment, with the engine and transmission integrating without clearance issues, and headers and exhaust aligning perfectly.
Another invaluable resource for any Hemi swap project, and particularly relevant when considering the nuances of integrating modern systems like OBD2 into older vehicles, is Bouchillon Performance Engineering. Bouchillon specializes in those essential, hard-to-find components that bridge the gap between classic car parts and modern engine technology. Randy Bouchillon’s expertise in Gen III Hemi swaps is unparalleled, and their readily available advice and high-quality, crucial products are invaluable for these builds. They can provide insights into making the modern ECU and potentially OBD2 systems work harmoniously within the older vehicle’s electrical architecture.
This project spanned five months, extended due to parts delays during the COVID-19 pandemic. Under normal circumstances, a similar swap could potentially be completed in a month with readily available parts.
Key Resources Used:
- Holley Gen 3 Hemi Swap Components
- DIY Hemi Swap Information
- Bouchillon Performance Engineering
- Moparts Forum Hemi Swap Discussion
- MotorTrend Gen III Hemi Fitment Guide
- Allpar Modern Hemi Engine Overview
- Dodge Garage Gen III Hemi Guide
Detailed Parts List for a Gen III Hemi Swap
The following comprehensive parts list details nearly every component used in this Hemi swap project, excluding common fasteners. Part numbers and the rationale for each part are included where possible. Remember, labor and any custom fabrication are not included in the cost breakdown. This detailed list can be extremely helpful for anyone planning a similar swap, whether on a ’69 Satellite or considering modernizing a ’68 Plymouth GTX.
Alt text: First page of a detailed parts list itemizing components used in a Gen III Hemi swap project, useful for planning similar classic Mopar upgrades.
Alt text: Second page of the Hemi swap parts list, continuing the detailed breakdown of components required for a successful modern engine installation in a classic Mopar.
Engine Swap Notes and OBD2 Integration Considerations
Initially, sourcing a used 5.7L Hemi from a salvage yard was considered. However, concerns about the engine’s history and availability of reputable sources led to opting for a new crate engine. While companies like Cleveland Performance and MARS LS Swap offer comprehensive swap packages, the Mopar Performance crate engine provided a reliable and well-supported foundation for this project. The crate engine, sourced from moparproshop.com, proved to be a straightforward installation. Upon installation, the engine started immediately, and all components functioned as expected.
For optimal integration and a cleaner engine bay, the ECM was located under the dashboard rather than in the engine compartment. To maintain a classic aesthetic with modern functionality, a Dakota Digital Gauge Cluster was installed. Crucially for diagnostics and monitoring, the Dakota Digital BIM-01-2 OBD-II/CAN module was essential. This module allows the Dakota Digital gauges to receive tachometer and oil pressure signals from the modern ECM, highlighting the integration of OBD2 data in the classic dashboard. This is a key step in achieving OBD2 compatibility in a classic Mopar like a ’68 Plymouth GTX, enabling modern diagnostic tools to be used with the swapped engine. It’s noted that this module is necessary due to Mopar’s approach to aftermarket tuning, but it provides the desired OBD2 interface for monitoring engine parameters.
The crate engine comes pre-filled with oil, but the oil pan replacement necessitates adding approximately 7 quarts of oil. To further enhance the engine bay’s appearance, engine covers from a 6.4L Hemi were adapted, and the AC system was deleted, replaced with a Vintage Air blanking plate for a cleaner look.
Alt text: A Gen III Hemi engine neatly installed in a classic Mopar engine bay, showcasing a clean and modern appearance within the vintage vehicle.
Transmission and Driveline Upgrades
Upgrading from the original 904 transmission to a 727 added a layer of complexity to this swap. This necessitated finding a new column shifter cable, eventually sourced from ididit. For the transmission kickdown, Bouchillon Performance Engineering provided a well-engineered throttle pressure system assembly, albeit a pricier solution. These transmission upgrades are crucial for handling the increased power of the Hemi and ensuring proper drivability.
Alt text: Overview of the completed Hemi engine swap in a classic Mopar, demonstrating the successful integration of modern powertrain technology into a vintage vehicle.
This Hemi swap project demonstrates the exciting potential of blending classic Mopar style with modern performance and technology. For enthusiasts considering similar upgrades to their ’68 Plymouth GTX or other classic B-bodies, this detailed walkthrough and parts list offers a valuable roadmap. Embracing modern engine technology, including OBD2 systems for diagnostics, allows classic cars to deliver both vintage appeal and contemporary reliability and performance. Happy swapping!
