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Early Hemi Swap Details
This page highlights specific information for the enthusiast who wants more power under the hood and is considering the Early Hemi engine to accomplish that goal. In recent years, these engines, such as the 331, the 354 and the popular 392 Hemis have become more desirable due to their uniqueness and nostalgic appeal. Also, more and more suppliers have come into the market offering repair and performance parts for these engines.

Duffy Armitage, a fellow enthusiast and owner of a '70 D-100 with the 392 Hemi installed, is quite familiar with the Early Hemi swap. He generously detailed many fine points of this swap expressly for this Website, and his valuable information is the basis for this page. See also the more generalized Engine Swaps page for additional information on swapping engines into these trucks.

Image courtesy of Duffy Armitage.
The 392 Hemi Engine was used in the fifties as Chrysler's larger V-8 powerplant. It was installed in a variety of applications, including trucks, passenger cars, industrial, and marine uses. The Hemi's most revolutionary feature is the use of a hemispherical combustion chamber which maximizes power and efficiency.

In regards to `61-`71 Dodge Trucks, the swap is not a difficult one to achieve with proper research, a little ingenuity and the correct parts to adapt a more modern transmission. As Duffy Armitage puts it, "The swap to an Early Hemi is really a straight forward and simple one." In fact, Duffy's information also applies to the 331 and 354 Hemis along with the 392 which was his engine of choice. Read on and find out what is necessary to complete this unique swap into your `61-`71 Dodge Truck.

The early Hemi Engine is easy to mount in that it has the same mounting bosses as the Wideblock or Polysphere 318 engine, which was installed in these trucks until the `67 model year. Simply obtain a set of Pre-`78 truck motor mounts for a Polysphere 318 engine or the LA-318 and bolt them onto the appropriate side mounting bosses on the Hemi. For rubber insulators, look to the Slant-Six or Polysphere 318--these will fit the chassis and motor mounts properly. Engine location in the compartment is much like that of the Polysphere 318, since the dimensions are quite similiar. It should just drop right in.

There are a variety of choices for transmissions to back up your Early Hemi, however, the most obvious choices are the A-727 automatic or the A-833 4-speed. A number of companies make adapters for Chrysler automatics, and some manufacture parts to adapt a manual transmission. For the automatic, the adapter is used to correct the difference in crank flange on the Early Hemi engine. The small block Mopar engines and the Early Hemis have a common bellhousing bolt pattern, making the choice of transmission easy.

See also Dave DeGan's Hemi Page for more information on adapting the A-833 transmission.

The adapter makes the engine/tranny combo 5/8" longer than a stock 318 and 727 automatic, but the difference is slight. Everything should fit the OEM automatic transmission crossmember in these trucks. If your truck has a manual transmission, modifications such as a custom crossmember or installing a used automatic crossmember may be necessary. Most later (`68-`71) trucks have both crossmembers and can be easily adapted to the new combo with little or no modifications. In either case there are two ways to adjust the combo to fit like the "intended" engine/tranny setup. Simply bolt the engine mounts to the back of the engine mount bosses to make up for the extended 5/8" (due to the adapter) or bolt in the combo as per normal and use the adjustment slot in the stock automatic tranny crossmember. Either way should work, both with the truck and driveline.

The Early Hemi is balanced much like pre-`71 Mopar small and big block motors. For the automatic, the hot ticket is to use the 340 or 383 Magnum torque converter. A B&M flexplate will facilitate the connection to the 8-bolt crank flange, which is just like that of the 426 Hemi.

It is possible to use the same driveline if:
A.) you have the passenger car automatic or 4-speed and
B.) you have the automatic truck driveline.
Most driveline or tranny shops can inexpensively modify a driveline for you in the event that you need to make some changes to your existing setup.

A later (`68-`71) column will easily adapt to your automatic linkages, and includes the shifter as an integral part of the assembly. As for linkages, it is recommended that the OEM later truck linkages also be used. Kickdown parts can be had from a C-body Mopar with some modifications to the length of the rods down to the tranny and over the intake manifold. If you're planning on a dual quad setup, simply modify the linkages from the C-body. Aftermarket dual quad linkages may work, but are known to bind within normal use.

Internal Engine Parts - The 340 double roller timing set will fit all Early Hemi Engines. For the 392, one can also use connecting rod bearings that fit a 440.

Positive Crankcase Ventilation - In order to get rid of the road draft tube and install a PCV system, you can use parts from a `60's small block Mopar engine. The basis for this is the grommet from the passenger side small block valve cover. Place this part in the road draft tube hole (on lifter valley pan), then add your PCV valve and grommet to the grommet in the valley pan.

Alternator - Duffy used the triangular bracket from the small block application along with the adjustable slotted bar from a pre-`62 Mopar generator setup. This arrangement works well with the stock water pump. For other pumps, in particular the Ch#*y Big Block variety, it is recommended to use the appropriate adapter from the companies that made the kit to adapt the pump.

Pumps - it is possible to use the stock water pump, but for better efficiency you may want to look into the parts available from various Early Hemi outfitters. They can offer a variety of pump solutions, pulleys and brackets to prepare the driven accessories of the vehicle. This includes the fuel pump and even the power steering pump if needed. In most cases, the brackets and pulleys are the most difficult part of making these items work with the Early Hemi engine. It is possible to use an electric fuel pump in place of the mechanical pump. Adapters are also available for the more common small block Mopar fuel pump which properly align the pump arm to the Hemi fuel pump eccentric.

Pulleys and Balancers - The stock Hemi balancer or a new balancer for the same can be used. Pre-`71 B-engine balancers will also fit but must be re-indexed with the proper timing marks. If the stock damper is used, it can be shimmed with a 1/16" plate to accept any pre-`71 crank pulley originally used with a balancer. This will properly align the crank pulley with the rest of the driven accessories.

Cooling - A `69 C-body big block radiator was used in Duffy's D-100, as well as an aftermarket transmission cooler. Most Mopar radiators have a 4-bolt mounting method, and are for the most part interchangable. The toughest part is matching up the hose outlets. The `69 C-body radiator worked well under these conditions, along with the aftermarket tranny cooler.

Oiling System Items - Both the passenger car Early Hemi oil pans and the larger truck pans will work well this application. Armitage also recommends a remote oil filter setup, which acomplishes two things. First, it does away with the annoying canister type filter on these engines, and it makes the filter more accessible for maintainence purposes.

Ignition - The stock dual point distibutor that is found on most Early Hemis works with this swap. Some tranny adapter suppliers also carry adapters for the later small block distributor, which would allow for endless posibblities in regards to ignition systems. The recommended setup for best performance and low maintenance is, of course, the Mopar Electronic Ignition Conversion Kit.

Two types of stock exhaust manifolds were made for the Early Hemi. The larger, "300" series car or truck manifolds are the best choice and come with a 2 1/2" outlet. Standard passenger manifolds will also work, but they don't flow as much as the larger 300/truck versions do. The Sanderson Header company makes a set of block hugging headers that will also work well in the truck application. At a bare minimum, 2 1/4" pipes are recommended for the rest of the exhaust system while 2 3/4" to 3" diameter tubing will also fit the truck.

See also the Exhaust Suggestions Page on this site for further information on a high quality exhaust system.

Image from How to Build Chrysler, Dodge, Plymouth Hot Rods
Here are some contacts for parts, information and otherwise in regards to Early Hemi Engines. If you know of a valuable resource not listed here, please send in an Online Response detailing the proper information. By the way, the image above is of an Early Hemi industrial engine installed for use as an air raid siren powerplant (if you can believe it). As the caption under the picture used to say, this is how the engine, "was originally installed circa 1952".

Above: Early Hemi parts and cores are available if you look hard enough. These were seen at a swap meet. Although it was difficult to tell what condition this engine was in, it looks to be nearly complete with a few spare parts.

This `53 331 Hemi block, complete heads, core heads (right) plus other miscellaneous items (scattered) were available for $150 at the swap meet. All this core needed to be complete was engine internals, intake/exhaust manifolds and a rebuild kit.

Early Hemi Websites

The Early Hemi Registry
Tons of info on all Early Chrysler Hemi Engines.

Dave's Early Hemi Page
Information, etc. (you could call it an Early Hemi Mecca)

Irish Jr's Site
Hemi Enthusiasm, an Early Hemi project car and a Hemi parts swap arena.

Chrysler Central's "Hemi Central"
General information and serial number details.

The Infamous Hemi
In-depth history and technical information on all Chrysler Hemi Engines.

Early Hemi Organizations/Sources
If you're in Australia, check with Rob Thompson of the American Hemi Speed Centre. He is a resource for information and parts in "down under" locales. He also offers a newsletter, titled the Hemi-Spherical Power Connection which is an excellent resource in itself. Information:
Rob Thompson
The American Hemi Speed Centre
Post Office Box 130
Golden Grove
South Australia 5125

Early Hemi Parts Sources
Power Play Early Hemi Parts
Route 1, Box 95
Lowgap, N.C. 27024
Power Play offers specialty parts, adapters and engine building services for your Early Hemi Engine.
Hotheads Research & Racing Early Hemi Home
P.O. Box 9132
Apache Junction, AZ. 85278-9132
Fax: 602-671-9132
Nearly anything and everything to outfit your Early Hemi engine and its installation in the vehicle.

Automotive Innovations Unlimited
1014 W. Barkley Street
Orange, CA 92868
Tech Info: (714)-639-7625
Orders: 1-800-489-9923
AIU offers complete rebuild kits, Early Hemi core engines, rebuild services as well as a wide variety of specialty components and adapters for these engines.

Egge Machine Co.
11707 Slauson Ave.
SantaFe Springs, CA 90670
Egge Parts House offers pistons and other parts for Early Hemi engines.
Kanter Auto Products
76 Monroe St.
Boonton, NJ 07005
(201)-334-9575 or
Fax: (201)-334-5423
Kanter Auto Products offers a huge selection of Early Hemi Engine parts, and other old car and truck items.

Quality Engineered Components
1150 Ryan Court
West Lynn, OR 97068
A-833 4-speed tranny adapters, information and other parts for Early Hemis.

Sanderson Headers
202 Ryan Way South
San Francisco, CA 94080
Sanderson sells headers for Early Hemis. Their headers are conveniently available online through Century Performance. More Info:
Centruy Performance
2601 W. 7th Street
Reno, NV 89503-3325
Phone: (775) 770-1057

Wilcap Company
P.O. Box 14232
San Luis Obispo, CA 93406
Adapters for Mopar and Ch#*y transmissions as well as front covers and finned valve covers.

Performance Automotive Warehouse
21001 Nordhoff St.
Chatsworth, CA 91311
Fax: (818)-407-7204
Rod and main bearings as well as performance cams for the Early Hemi.

Chris Neilson Cams
Box 416
Farmington, UT 84025
New cams for Early Hemis.

Reath Automotive
3299 Cherry Avenue
Long Beach, CA 90807
Early Hemi parts.

Hyatt Engineering
547 Sinclair Frontage Rd.
Milpitas, CA 95035
Transmission adapters, Early Hemi parts.

Smith Bros.
1320 Southeast Armour Road
Bend, OR 97702
Early Hemi pushrods.

Weiand Automotive
2316 San Fernando Road
Los Angeles, CA 90065
Weiand manufactures performance intake parts, including a dual four barrel intake manifold as well as blower manifolds for Early Hemis.

Offenhauser Sales Corp.
5300 Alhambra Ave.
Los Angeles, CA 90032
Offenhauser makes intake manifolds for Early Hemis.

Hale Performance
Box 1518
Van Buran, AR 72956
Hemi Specialists.

Federal Mogul
26555 Northwestern Hwy.
Southfield, MI 48034
Carbs, engine and miscellaneous parts for nearly all engines. Available through distributors.

FelPro Inc.
7450 N. McCormick Blvd.
Skokie, IL 60076
Fel-Pro offers high quality gaskets which will fit the Early Hemi engine.

A very special thanks to Duffy Armitage for his assistance with this topic. If you would like extra advice or further information about Duffy's Early Hemi powered 1970 D-100, e-mail him at

Please Note: This page is intended as a guide for the project outlined, and is not guaranteed in any way. The information was supplied at the request of the author and is merely an extension of what was received. All the info is to the best knowledge of the author. Comments? Send in an Online Response.

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