It's difficult to argue with the old adage, "There's no substitute for cubic inches." But, it's always fun to build an engine that performs like it has a larger displacement than it actually does. There are also practical benefits to upgrading the power-producing capabilities of a smaller engine. In the case of small-block Mopars, 340 and 360 engine cores are increasingly harder to find, and when one is located, it tends to be expensive.
That was the dilemma Mickey Hamilton faced when he began building a '67 Barracuda for street/strip use. "I started out intending to build a 360," Mickey says, "but I couldn't find one at a decent price. But, every time I went looking for one, I tripped over a 318. Finally, the light came on, and I figured since I was working with Andy Giles, who is a great engine builder, I could give up 42 cubic inches and still get an engine that would put the car into the 12s at the strip."
Andy is one of those engine builders who never attended a trick-of-the-week training class. He takes a straightforward approach and concentrates on refining proven techniques and components. He also has a knack for wringing amazing amounts of horsepower from engines built almost entirely from stock or stock-replacement-type components. As the dyno test figures demonstrate, his approach delivers high-dollar horsepower figures at low-dollar expense.
Since this engine was to be suitable for street driving as well as dragstrip use, Andy didn't set out to build a full-tilt race engine. Realizing many Mopar lovers would like to boost the output of the engines in their exclusively street-driven cars and pickups, he started with a stock rebuild to establish a baseline. Then, he developed a number of combinations, each of which raised the horsepower bar a bit higher. At the conclusion of the test series, maximum power had risen from 187 to 357 hp, and torque jumped from 305 to 388 lb-ft. The best part about the power increase is it was achieved with nothing more exotic than ported cast-iron heads and a custom-ground hydraulic-lifter camshaft.
Does this engine look like it can propel a '67 Barracuda to 12-second quarter-mile e.t.'s?
Before the rebuild, Mickey's engine spent its life as the motorvational source for a '73 Dodge Dart. Despite its age, it had relatively low mileage and was in excellent running condition. Equipped with its original two-barrel carburetor, 151/48-inch Hedman A-Body headers, and 3-inch exhaust system with Random Technology PowerMax mufflers, the 318 displayed its plebeian ancestry, cranking out a maximum of 187 hp at a mere 3,750 rpm.
Andy's rebuild involved all the normal machining, including a .060-inch overbore and torque-plate hone. He also align-honed the main-bearing bores and deburred the block. After the machine work was completed and the block thoroughly cleaned, the short-block was assembled using reconditioned stock connecting rods, hypereutectic pistons (9.8:1 compression ratio), Hastings rings, Clevite bearings, Fel-Pro gaskets, and a Comp Cams hydraulic-lifter camshaft.
To start the testing, a Comp 270H cam with .224/.224 at .050 duration and .470/.470-inch lift was chosen. With intake and exhaust duration of .224 degrees at .050 lift, the camshaft was definitely on the aggressive side for a 318 (now 328 ci by virtue of the overbore). But, specific timing points and a lobe-separation angle of 110 degrees provided a relatively smooth idle and good low-speed torque.
The short-block was topped off with the original heads that were pocket-ported prior to installing Mopar Performance 1.78- and 1.50-inch valves. Andy also performed a multi-angle valve job and gasket-matched the port openings. Of course, the stock two-barrel carb and manifold were consigned to doorstop duty. In their place, he installed a 340 cast-iron manifold and topped it off with a 625-cfm AVS carburetor.
After removing the intake, our 318 core was looking good.
When removing the camshaft, we found moisture had gotten into the engine, evidenced by rus
A good set of heads is essential to airflow. Aluminum aftermarket heads may support higher
The amount of port work required is directly proportional to the flow numbers needed. In t
A "360" cast into the cylinder head identifies its original installation. These heads are
The 2.02/1.60-inch valve combination fills the combustion chamber. Modifications to the ch