Build Yourself A 500HP Chrysler For $5,000*

Most of the LA engines were internally balanced, with the exception of the 360, and Johnson told us that can cause some complications when mixing and matching parts. Stroker cranks are usually internally balanced, so when stroking a 360, you'll need to find a neutral balanced damper and flexplate/flywheel. If you're planning on reusing your stock 360's torque converter, be sure to check it for counterweights. At the factory, torque converters destined to go behind 360s were balanced to match the crank, so installing one of them behind an internally balanced crank will cause journal-snapping problems. The weights were welded on, so you may be able to knock or cut them off. We'd recommend buying a neutral-balanced, performance torque converter, though.

Our next trip took us out of the confines of Los Angeles county to visit Indio Motor Machine (IMM) in Indio, California. IMM is operated by father and son team Fred and Brian Hafliger, and though they build all engines of all makes foreign and domestic, these guys have quietly developed reputations as small-block Chrysler experts. Brian spent an afternoon discussing build combinations with us and had several parts on hand to show us. First off is a comparison of LA blocks. That's a 318 on the left and a 360 on the right.

Fortunately, Chrysler blocks are clearly marked with their displacements. Look for the engine size cast into the block just below the deck on the left side (driver side) of the block.

We also should thank the Chrysler engineers for blessing the LA with a good bore spacing and big bore sizes right out of the box. Unlike Chevy's 305, the diminutive-sounding 318, with its 3.91-inch bore size, is much closer to the magical 4-inch performance standard and therefore has much more performance potential than any 305. Notice all the extra material between the cylinders of this 318 engine block.

Brian told us it's not only possible to bore out a 318 to 4 inches, but he's done it many times. He thoroughly sonic-tests the block to make sure there are no weak areas in the cylinder barrels before doing this, though. He likes to leave at least 0.120 inch of material on the thrust side of the bore and 0.100 inch on the nonthrust side and won't bore out a block that will measure less than 0.090 wall thickness anywhere in the cylinder. That's a 4-inch head gasket held up to a 318 block, demonstrating the difference in diameter.

Though most of his customers build 360s, Brian said there are a couple of advantages to building a 318. First, people are giving them away. He paid $50 for the 318 on the left-and that was for a complete short-block. The 360 on the right can cost a couple hundred dollars more just for a bare block. A second advantage to building a 318 is the main bearing journals are smaller than the 360's. All LA blocks have a 2.69-inch main bearing journal diameter, with the exception of the 360, which has 3-inch mains. The smaller diameter of the 318 or 340 block means lower bearing speeds, less heat, and longer bearing life.

Whether you choose to start with a 318 or a 360 as seen in this picture, you can see why it is so easy to drop in a 4-inch-stroke crank. There is a ton of room in the crankcase to fit that big arm. A 318 stroker built out of a block bored out to 4 inches equals 402 cid (6.6 liters), by the way. A 0.030-over 360 stroker adds up to 408 cid.

Continuing our theoretical build, we turned our attention to the induction side because extra cubic inches are worthless if you can't efficiently ventilate them. Brian showed us a pair of stock 318 heads, and the ports are laughably small and convoluted. That's not surprising, however. There was never a performance version of the 318, so don't expect any factory 318 heads to show stellar flow numbers, except for maybe the Magnum versions.

Of course, you could build your engine with 340 or 360 heads, but factory heads with goods ports and chambers may be difficult to find, so Brian recommends buying a pair of RHS' new Pro Action 360 X cylinder heads. At $320 each (unassembled), these things are a steal. They outflow any factory LA head straight out of the box and have a lot of room to grow with potential for porting and grinding for bigger valves.

The RHS intake runners measure 179 cc. In addition to being bigger than stock, they offer a more direct path to the valves. Brian said with porting, the intake runners can be increased to 190 cc. The exhaust runners measure 62 cc, as do the combustion chambers. They are designed to use 1.92/1.625-inch valves.

The 360 X heads come in two different flavors: LA-X, and MA-X for LA and Magnum engines, respectively. You can bolt the shaft mount system right on the LA-X heads, or if you wish to switch to a pedestal-type system and run less expensive Chevy rocker arms, there are bosses (see arrow) you can have drilled and tapped for rocker studs.

Hughes Engines specializes in small-block Chrysler performance, and we spoke with a couple of the company's tech guys on the phone. They recommended using a shaft mount-style rocker arm system but stressed the importance of setting up the valvetrain properly. Though the cost is initially higher, the best bet is to use adjustable rocker arms and custom-length pushrods. They'll lend you a kit to set all your angles correctly and measure for the right pushrod length. Send the kit back and they'll send you a set of pushrods. They spec'd out a stout 480hp engine for about $5,000, and that's the build we priced out in the chart at the end of the article. If you prefer to cut right to the chase, you can buy a complete engine from them.