Ariel-Norton Hybrid Motorcycle

Four in a featherbed
By Robert Smith
March/April 2010

Jerry Romano's "Square Norton" - an Ariel-Norton hybrid.
Photo by Robert Smith
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The Ariel Square Four

The Ariel Square Four was one of the most glamorous and best known British motorcycles.

If you wanted to find Jerry Romano’s Square Norton special at the October 2009 Barber Vintage Festival, all you had to do was follow the crowds. Every time Jerry parked his beautiful Ariel-Norton special, just about everyone would stop what they were doing and gather round — it really is that special.

You see, many have tried to fit Edward Turner’s famed double-twin, the 997cc Ariel Square Four, into a Norton Featherbed frame, and most have abandoned the attempt. A small number have been successful, but usually by performing a “cut and shut” on the iconic frame’s tubing, spoiling its integrity and compromising its strength and rigidity. That makes Jerry Romano’s Square Norton all the more special, because Jerry was able to fit the big lump without chopping the frame apart.

And his bike’s special nature doesn’t stop there: The engine came from legendary Ariel four tuner and one-time Egli Square Four manufacturer Tim Healey, and it’s received a number of improvements for performance and reliability. So how did Jerry Romano’s Square Norton come about?

Dime a dozen?
Jerry describes himself as a “retired wrencher from General Motors, just an old shop rat,” and makes his home in Clarkston, Mich. He has a number of restoration projects under his belt, including various BSA Gold Stars, Spitfires and a Rocket Gold Star, as well as Vincents, Triumph twins and a 1929 “cammy” Velocette KN. Among all of the parts he and a buddy had accumulated were a couple of Norton Featherbed frames and an Ariel Square Four MkII engine. “We had the Norton frames, and we were going to make a Triton, but they’re a dime a dozen,” he says.

He also considered building a Norvin but couldn’t find anyone to part with an engine. “So I thought: What about putting the Square Four engine in the Norton frame? My buddy thought it wouldn’t fit,” says Jerry. He even consulted a knowledgeable motorcycle journalist who told him it couldn’t be done without cutting the frame.

“I measured it and it looked like there was enough room,” Jerry says, “so I assembled a set of empty cases and got them into place without any trouble. I put the engine as far forward as possible and moved the swingarm mounts. I used the stock Ariel primary case and found it was an inch bigger than it needed to be, so I took half an inch out of it.” Jerry suspects the same primary case was used for Ariel’s twins and big singles, which may well have used a larger clutch sprocket.

And while it’s true he didn’t have to drastically cut into the frame to fit the Ariel lump, he did have to modify the frame a bit to make it all work, adding extra engine mounts, trimming the transmission plates and “easing” the frame tubes to allow the engine to be shoehorned into place.

“There was no room for the Manx oil tank, so I mocked one up out of cardboard to fit,” says Jerry. The result is a tank that looks like a Manx oil tank and holds the requisite four quarts of oil. The rear wheel and drum brake came from a conical-hub Triumph, while the front forks, front brake and front wheel came from a 1949 “Garden Gate” (plunger rear suspension) Norton International. A Manx short-circuit gas tank and Manx seat added to the period Norton look.

The Healey Connection
The engine is a 4-pipe 4G MkII dating from 1954. A friend of Jerry’s had acquired a number of Square Four frames and engines, which eventually became part of an estate sale; Jerry acquired a complete Square Four from this same batch, together with a spare engine.

The Ariel Square Four engine dates back to 1928, when Edward Turner, then a motorcycle dealer, showed his innovative design to Ariel boss Jack Sangster. The design, a sophisticated 500cc overhead cam engine, became the Ariel Square Four and was launched at the Earls Court motorcycle show in London in 1930. The original 4F Square Four used two crankshafts connected by helical gears with the overhead cams driven by a shaft and bevel gears. Over the years, the Square Four became 600cc, then a full 998cc with the OHC being dropped in 1937 for more conventional (i.e., cheaper) OHV gear. The first post-WWII machines used an iron cylinder block and head (4G MkI, distinguishable by the 2-pipe exhaust header), but with wider availability of aluminum, the cylinder head became light alloy with four header pipes (4G MkII).

When parent company BSA Group pulled the plug on Square Four production in 1958, Ariel tuner and sprint racer Tim Healey accumulated a huge collection of spare parts. He planned to go into production with the Healey 1000/4, using the Square Four engine in an oil-bearing spine frame designed by Fritz Egli. Later versions were fitted with Ceriani or Spanish Betor forks and a 230mm double-sided Lockheed disc brake on the front. At just 355 pounds dry, the Healey 1000/4 was good for 126mph. Performance was better than sales, however, and Healey abandoned the project after selling just 28 machines.

When Jerry got his Square Four engine it was locked up. That meant he was looking at a complete rebuild, so he went to work dismantling it. At the front of the engine it was stamped “HEA 16.” That mark follows Healey’s identification strategy, indicating it was a Healey engine. Another clue was the Lucas 4-cylinder magneto, which Jerry believes is similar to those fitted on MG car engines in the 1950s. Healey engines also had a special camshaft and benefited from an improved oil pump, filter and cooler. Other than shaving the cylinder head for increased compression (the Healey used a lowly 7.5:1), Jerry has left the engine alone, which should mean it’s making a little more than the 52hp of a regular Healey engine. By comparison, a standard Square Four was rated at a modest 42hp. After consultation with U.K. Ariel specialists Draganfly Motorcycles, Jerry decided to retain the stock SU carburetor, which the folks at Draganfly say is the best option for the Ariel engine.

The finished product
Aside from figuring out how to shoehorn the Square Four into the Featherbed frame, “everything else flowed,” Jerry says. The rear wheel came from an oil-in-frame Triumph, Jerry found a set of aluminum blade fenders and fabricated braces to fit, added a Smiths Chronometric speedometer, and the rest seems to have come together naturally. In fact, what’s most impressive about Jerry’s special is that it looks like everything was supposed to go together. The frame could almost have been made for just this bike, to wrap around the big 4-cylinder lump and its Burman transmission. Jerry’s bike weighs just 410 pounds complete with a tank of gas, so it makes the most of the big engine’s torque. “Rolling on the throttle in first gear will break the rear tire loose,” Jerry says.

The part of the project Jerry found most satisfying was the work he did to the frame to make the engine fit — without cutting it apart. “The work I had to do to the frame was really neat,” he says. “I like a challenge. I didn’t want to cut the frame and change the dimensions.”

But what Jerry finds most gratifying about the finished project is the reaction of people who see it for the first time. “I never knew Norton made a 4-cylinder” is a common response, he says. “Even the guys with newer bikes and Harleys say ‘that’s cool.’ The president of our local Norton owners club was going to pay my dues and make me an honorary member!”

Coming up with the name was a challenge. Jerry considered Noriel, but rejected it. “It was a toss up,” he says. “I settled on Square Norton because everyone who’s into old bikes knows what a Square Four is.” Would Jerry build another Square Norton? “I’ve got another Square Four engine [and he also has more Featherbed frames], so I could make another one, but there’s no challenge in that.”

Thinking of building one yourself? Jerry has some advice: “If you’re mechanically inclined, and have access to a lathe and mill — have at it! But you’re going to have to make a lot of parts!” MC

Resources
Draganfly Motorcycles
www.draganfly.co.uk 


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