Truckin' decided that we would find an engine shop in California that was familiar with installing a stroker kit into a 302 to demonstrate the procedure. We ran across a group of experts at Smeding Performance in Rancho Cordova, California, who specialize in building small-block Ford and small-block Chevy stroker engines. Ben Smeding and his group of machinists and salesmen are about the most dedicated group around when it comes to quality work. Over a period of a few days, these guys walked us through a 347 Ford buildup that was very impressive.
First, the Smeding Performance small-block 347 Ford is a new engine with all new components. The engine block is brand-new, straight from the Ford Motor Company, along with the stroker kit and new Edelbrock aluminum heads. Nothing is rebuilt or reused; the engines even come with a new timing chain cover and a new oil pan.
The engine is called the Ford 347 Extreme and sells for $4,895 out the door. It cranks out 380 hp at a low 4,600 rpm. The engine's relatively mild hydraulic roller camshaft really pumps up the low-end torque, while still producing excellent horsepower and giving the engine an impressive sounding idle. Starting with the small and lightweight size of the 302 Ford and adding the aluminum Edelbrock heads and aluminum intake manifold, a person would be hard-pressed to find a more compact street engine with a better power-to-weight ratio than the 347.
Before we get into the specifics of this powerful engine, some of the disadvantages of the stock 302 Ford need to be pointed out to compare them with the upgrades found on the Smeding Performance Extreme Ford.
The Stock 302 Ford
Other than the lack of engine displacement, the biggest drawback to the 302 Ford is the size and strength of the connecting rod bolts and nuts. The most critical point of strength on the connecting rod is the bolt and nut holding it together. No expense is spared in the quality of the bolt and nut on the connecting rod of a high-performance racing engine. All modern American-made V-8 engines will have a connecting rod bolt and nut that measure at least a 3/8-inch diameter. Some big-block engines will have a larger 7/16-inch diameter bolt and nut, with the Boss 429 Ford having connecting rod bolts that measure a full 1/2 inch in diameter. The 302 Ford has small 5/16-inch diameter connecting rod bolts and nuts. While there are many highly modified 302 Fords running around out there with the stock connecting rods, the truth of the matter is they are living on borrowed time.
The size of the intake and exhaust ports in the stock 302 head are very small. Port size is measured in liquid volume. The intake port of the stock 302 cylinder head holds 145 cc of liquid. To equal the port flow of a stock Chevy small-block intake port, the Ford's intake port volume needs to be increased to at least 160 cc. The exhaust ports in the Ford head have a hump that restricts exhaust flow. Called the thermactor port, it is designed to work in conjunction with emission controls to introduce air into the exhaust. Most American-made V-8 engines introduce air into the exhaust manifold and do not have a restricted exhaust port like the Ford. The stock valve diameters of a 302 Ford are also very small.
The intake valve measures 1.78 inches and the exhaust valve measures 1.45 inches. The intake and exhaust valves of a stock 350 Chevy measure 1.94 and 1.5 inches in diameter. The 3/8-inch diameter rocker arm studs have been eliminated on the '78-and-later 302 Ford heads. The rocker arms are held in place with smaller 5/16-inch-diameter rocker arm bolts.
The '69-and-later small-block Ford engines will not have adjustable valvetrains. Valve lash adjustments are accomplished by installing different length pushrods. Most American-made V-8 engines have the intake ports paired together at the ends of the cylinder heads. By pairing the intake ports together, an excellent intake manifold can be designed with equal-length passages and gently sweeping turns between the carburetor and the intake ports. The intake ports are different on a Ford engine. They are spaced evenly across the cylinder head, with some intake ports located very close to the carburetor and some located far away.
Designing a compact intake manifold that incorporates equal length passages between the carburetor and intake ports requires some tight radiuses on the turns. To design a manifold for a Ford with equal length runners, gently radiused turns, and the same flow capacity as other more conventional V-8 engines requires an aftermarket intake manifold with a high-performance design. However, the drawback to a high-performance design is that it mounts the carburetor higher on the engine.