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Small-Block Lite

World Products' all-aluminum Motown small-block is the "low carb" alternative

Mar 10, 2005

Just as your doctor has told you excess weight isn't good, so it goes for your Camaro. Never the most featherweight of muscle cars, Chevy's nose-heavy pony car benefits greatly with every shed pound-especially up front.

A fiberglass hood will shave some weight, as will a set of aluminum heads. But if you really want to lighten your Camaro's front end, World Products' new Motown "Lite" aluminum small-block crate engine might just be the ultimate weight-loss plan.

Although World Products has been offering Motown engine assemblies for a couple of years now, it only recently started building them with their all-new aluminum block. Compared to the standard iron block, the alloy version weighs only about half as much.

"With this block and aluminum heads, you get an engine that weighs only about 435 pounds," says World's Bill Mitchell. "That won't even compress the front springs on some cars."

Like the iron version, the alloy Motown Lite is strategically beefy. The 357-T6-cast bare block (with main caps and cylinder liners installed) weighs just 100 pounds-an iron Motown block weighs about 195 pounds.

Besides its light-grey aluminum coloring, the most obvious deviations from the World Products' iron small-block or, for that matter, GM's own small-block Chevy, is the horizontal strengthening ribs along the cylinder banks. They add strength and are connected internally to serve as cross-feed oil galleries.

The extra meat in the block's casting is mostly on the inside, so all the Chevy small-block accessories, from intake manifolds to fuel pumps, bolt up as with a stock engine. The extra metal, however, allows World Products to slip in some thick cylinder liners and create Mitchell's signature big-displacement torque monsters. A 427ci displacement is the maximum with a 4.000-inch crank (the iron block can yield a 454 displacement).

One of the block's other unique features is a series of O-rings at the bottom of the cylinders. They help hold the liners in place and prevent oil from squeezing between the liners and block - then bane of many aluminum engines.

"When it gets up there, the oil acts like an insulator and prevents the aluminum from transferring heat," says Mitchell. "It also helps dislodge the liners."On top of this lightweight foundation, World Products bolts on its time-tested roster of power-building components - each selected to help move air efficiently through the voluminous passages. Motown 220 heads, named for their huge 220cc intake runners, have equally large 2.055/1.600 valves.

Straddling the heads is Motown intake manifold topped by an 870-cfm carb. Technically it's a single-plane intake, but a unique "spider" design allows the engine to make useable low-rpm power and torque. This was important as Mitchell sees this engine as much as a street performer as a race engine.

"It's a great street engine," says Mitchell. "It idles great and makes lots of power down low; you can cruise all night with this."

Much of the street friendliness of the big-carb motor is due to a special-grind camshaft from Crane that produces great idle quality and very good high-rpm power. Not surprisingly, Mitchell wouldn't divulge the cam's specs, but our experience with his crate engines has shown that they seem to strike a great balance of power and tractability.

World Products rounds out their engine assemblies with an HEI-style distributor, plugs, wires, deep sump oil pan, and SFI balancer and a great looking set of valve covers. As with most other crate engine packages, vehicle-specific items, like the water pump and headers, are left to buyer to source.

Each engine, however, is dyno tested before being crated and shipped.

So, what'll it do?

What is the all-aluminum 427-cid Motown small-block worth on the dyno? At our writing, Mitchell was still trying to determine an average on which to base his advertised claims, but here's what he told us:

"They've been making around 535 hp and 540 lb-ft of torque," he says. "They run right up to 6,300 rpm, too."

Mitchell says he's surprised because the aluminum engine is making as much and, in some instances, more power than comparable iron-block engines. "It's puzzling," he says. "Power should have probably dropped a little, due to the thermal differences between the iron and aluminum, but we got just the opposite. It was a pleasing surprise, to say the least."

Mitchell attributes the engine's stalwart performance to the extra-rigid aluminum block and its numerous strengthening features, which probably provide less flex in the reciprocating assembly. Regardless, the lightweight small-block makes power--tons of it.

If you're thinking all this performance wrapped in a lightweight package must come at price, you're right. The all-aluminum Motown is not an inexpensive option. It adds approximately $2,000 to the bottom line of the base price of a Motown crate engine, and the iron-block versions of the 427 start at around $8,995.

So, you're looking at package of about $11,000 to $12,000 when they've nailed the crate shut and maneuvered the forklift into position.

But, compared to some exotic race castings, World's aluminum block costs roughly half and were designed as much for street performance as competition.

"We learned a lot in the manufacture of other parts that really helped make this affordable," says Mitchell. "We wouldn't have done it if we were building just 100, or so, each year for sprint cars."

There's an undeniable "wow" factor, too, that plays an important role. You wouldn't want to paint this block - just let the aluminum color and external ribbing do the talking under the hood of a Pro-Touring '69 Camaro"I think it'll look awesome polished," says Mitchell.

Indeed, others have thought so, too. Since making the all-aluminum Motown engine available, it has quickly become one of the company's best sellers.

It's hard to argue with the benefits of lower weight. Your doctor will tell you that, and so will Bill Mitchell.


The light grey color and cross-valley ribs are the clues that distinguish the Motown Lite block from iron versions. Like GM's small-block, the Motown Lite has a 9.025-inch deck height and all common small-block parts and accessories bolt right up.

Many things to note here: First, check out the bulging cylinders and front-to-back ribs. The bulges allow for large displacement and carry generous water passages. The ribs add reinforcing strength and promote cooling, as well. Also, the freeze plugs are screw-in type.

Motown Lite blocks come with 4.125-inch bore steel cylinder liners-the maximum bore that still leaves a sufficient amount of steel in the liner. Special O-rings seal the bottom of the cylinders, preventing oil from squeezing up between the liner and block. The oil acts like an insulator, trapping heat; it also can dislodge the liner as the aluminum and steel materials heat and cool at different rates.

World Products will initially offer the Motown Lite with 350- and 400-size mains.

The crankshaft is a Scat 4340 forged steel part that produces a 4.000-inch stroke. It is internally balance prior to installation.

The first batch of Motown aluminum engines will have billet steel, splayed main bearing caps (seen here). The engine also will be available with nodular iron main caps.

World Products wouldn't divulge the specs of the camshaft. We do know that it's supplied by Crane and is designed to give what Bill Mitchell says is "a great sound, great idle quality and great upper-rpm performance."

Forged aluminum pistons from Wiseco fill the engine's 4.125-inch bores and deliver an approximately 10:1 compression ratio--a great compromise of squeeze and pump-gas compatibility.

The rods are from Manley and they're H-beams made from 4340 forged steel.

A high-volume Speed-Pro oil pump is covered by racy looking Milodon dump-sump oil pan.

The all-important cylinder heads are more World Products castings. They're the Motown 220 heads that are cast so that the ports have fewer irregularities; i.e. they don't have to be ported for optimum flow.

The base 427 engine comes with 64cc chamber volumes, although heads with 72cc volumes are available. The chambers are accessed via Manley Sever Duty stainless 2.055-inch intake valves and 1.6000-inch exhaust valves.

Like the block and heads, World casts their own intake manifold, too. In the case of our aluminum 427, it's a single-plane design with "spider" dividers at the base, giving the engine the benefits of high-rpm performance and low-rpm power.

An 870-cfm carburetor is used. It's a modified Holley carb that is designed to provide great low rpm, "cruise night" performance without loading up.

The completeness of the crate engine package extends to the inclusion of many accessories, including a race-legal balancer.

World Products also installs an HEI distributor on each engine. And because each engine is dyno-tested prior to shipment, the engine is timed correctly, too.

Ignore the valve covers-they're for a different engine. Our visit to World Products was early enough in the development of the Motown aluminum engine that the correct valve covers weren't available. Nevertheless, what you see is what you get out of the crate. World says the engines is good for about 535 hp, 540 lb-ft of torque, and 6,300 rpm. We know they sandbag their power numbers, too, so we wouldn't be surprised if the true numbers were a little higher. Not bad for an assembly that ways a mere 435 pounds!


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