From the garage: Engine and transmission installation
The installation of the engine / transmission combination is one of the most important steps in any Hot Rod build. The goal is to get the combo as low as you can in the frame rails. This lowers the cars overall center of gravity and will lead to better handling, ride quality and stability. Of course, many things must be factored into the final position. Today we are going to look at engine placement in relation to steering clearance, exhaust clearance and cross member / steering clearance.
PART 1: STEERING CLEARANCE
Steering clearance can be the most restrictive aspect of engine placement. While exhaust manifolds can be traded for headers to solve exhaust clearance problems, most of the time changing steering geometry isn't a feasible option. The two points that have the most effect on engine placement are: steering linkage from the steering column to the steering box or rack and oil pan to cross steering linkage clearance.
COLUMN TO STEERING BOX OR STEERING RACK
A picture of the steering linkage from the steering column to the steering box. Photo by: Chris Breeden
Special attention must be paid to the rear of the engine and firewall clearance. This will ultimately determine where the engine rests in relation to the steering column coming out of the firewall. It goes without saying that the engine must be centered in the frame rails, to ensure even weight distribution. If a steering column comes through at an odd location, this must be factored into engine placement.
OIL PAN AND STEERING ROD CLEARANCE
Above: An example of a rack style cross member. Photo by: Chris Breeden
Cars using a steering box will always have a cross steering shaft. All cars will usually have a cross member that must be fractured into final engine placement location. Enough room must be left for steering clearance and a thought should be had for oil pan removal after the engine is installed.
PART 2: EXHAUST CLEARANCE
Note the tightness between the steering linkage and the exhaust manifold. Close, but safe. Photo by: Chris Breeden
Steering linkage, must be in place before engine mounts are constructed. Likewise with exhaust manifolds or headers. As much clearance as can be had is desirable, however a half an inch is pretty much universal acceptable clearance for steel steering connectors and exhaust components. Top Tip: Keep the direction the engine will torque in mind when setting clearances!
PART 3: GROUND CLEARANCE
Picture of oil pan ground clearance.
Ground to oil pan clearance can be a difficult measurement to calculate. Since you are installing the engine in the car without the engines own weight or the weight of the front sheet metal on the suspension. Suspension sag its something that can be estimated fairly easily. When you are setting the engine into position to begin making engine mounts, let the engine rest fully on the front cross member. Support the rear of the engine/transmission combo with a floor jack. By taking note of how much the suspension sags, you can estimate final ride height. Ground clearance is a personal taste thing. I feel comfortable with a 6 inch minimum. The oil pan in the above picture only has about 4 inches, a low profile oil pan is in this cars future!
PART 4: RADIATOR AND FAN CLEARANCE
Radiator to fan clearance is almost preset due to the firewall in most older cars. As a result of this, the stock radiator might not be able to be used in all applications. However, it is possible to move the radiator forward by altering where it mounts in the radiator saddle. In some drastic applications a smaller dimension radiator can be substituted as long as it will work with the engine that is being installed.
PART 5: ENGINE AND TRANSMISSION MOUNTS
The best way to fabricate engine mounts is to place the engine, with a cherry picker, into the engine bay. Make sure the engine is clear on all previously mentioned topics and that it is centered in the frame rails. Once all measurements and clearance issues have been satisfied, engine mount fabrication can be started. I make all of my engine mounts out of thick walled 2 1/2 inch square tubing and a piece of thick walled round steel with a 3/8 inch diameter center hole. (see pictures above for a step-by-step engine mount fabrication sequence.
Photo by: Chris Breeden
As you can see there are many things to keep in mind when installing a engine into a Hot Rod. By being mindful of the above things (steering, exhaust, cross member, fan and ground clearance) the installation of an engine / transmission combination can be one of the easiest things to do in the construction of a Hot Rod. The main thing to keep in mind: If something isn't right or a better idea is thought of later, the constructed engine mounts can always be cut out and new mounts constructed! Nothing is set in stone in the Hot Rod world and mistakes can be made. It is important to make sure the things that can be controlled are controlled, like weld penetration and basic clearances. By following the above points a Hot Rod engine can be installed that will offer years of reliable Rodding.
Keep on Cruisin'!
Art by: Chris Breeden
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About the Author:
"Chris Breeden is a Social Media content creator for Custom & Hot Rod Life on DRIVETRIBE, YouTube and Facebook. After spending 5 years in Southern California, a.k.a. Hot Rod Heaven, while serving as a jet engine mechanic in the United States Marine Corps, he moved back home to Tennessee with an even greater love for Hot Rodded Vintage Tin. Since then he has worked in retail sales and the transportation and logistics industry. In 2018, seeing a gap in Hot Rod and Custom Car coverage on DRIVETRIBE, Chris began advocating for their inclusion on the platform. During the summer months, he can be found all over the Tennessee region covering car shows, meets, and cruise-ins. During the winter months, he can be found in the garage working on his custom 1949 Ford two-door sedan and 1954 F100 truck."