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January 2003 Mail Box

Posted in Features on January 1, 2003
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Small-Block Roller RockersI'm building a high-performance small-block Chevy engine for my '74 C10 two-wheel-drive truck. The engine uses a balanced crank, forged JE pistons, a 268H Comp Cams camshaft, and a high-volume Moroso oil pump. The iron heads were ported and I installed thread-in rocker arm studs. I'm trying to button up the engine, but I was wondering if I should install roller rocker arms or just go with the stock stamped arms. Are the roller rocker arms worth the expense?Tom PaineUtica, Ohio

That certainly sounds like a stout small-block, Tom. True roller rocker arms use needle bearings at their fulcrum (pivot) as well as a roller on the tip that actuates the valve, and in many applications, they're worth as much as 10 total horsepower. Mostly, roller rocker arms show increased power at mid- and upper-rpm levels, and that 268H Comp Cam, with its 218 degrees of duration and 0.485-inch lift, is certainly intended for mid-rpm operation in a small-block. Even if an engine isn't going to see a lot of low-rpm action, roller rockers are worth the expense because they reduce friction at the rocker arm pivot at the area where the valve tip meets the rocker arms' tip. Roller rocker arms also reduce side loading of the valves, making for longer valve guide life, and, because of the low-friction bearings, roller rocker arms reduce engine and oil heat. Additionally, almost all true roller rocker arms are available in stock or increased ratios, which are an easy way to add lift to a cam. Finally, when selecting a set of roller rocker arms, choose wisely. There are economical stamped steel rocker arms with a roller tip but a standard ball fulcrum; the high-performance roller rockers are made of stainless steel or billet aluminum, use a true roller design, and are fairly pricey, but may be worth the cost, depending on the level of performance you're looking for.

Fair-Weather NissanI own an '87 Nissan 2WD prerunner truck that runs great until the weather turns cold or when it rains. The problem is a severe stumble when the manual five-speed transmission is shifted. The engine acts like it isn't getting enough fuel. Once the engine warms to normal temperature, the truck runs fine. I've replaced the fuel filter, the air filter, and the PCV valve, but there's no improvement. Can you offer any help?Henry LyleFlagstaff, Arizona

It sounds like you've checked the obvious, Henry, and because replacing the filters and the PCV valve didn't do the trick, you'll probably have to take the truck to a Nissan dealer or a Nissan-savvy independent repair shop. Ask the service manager to check the engine's cold-start system, which provides additional fuel when the engine is cold. There's a thermostat-controlled switch that operates a cold-start valve and keeps it open until the engine reaches full operating temperature. After the engine is warm, the switch closes the valve. We think you'll find the valve is stuck or burned out and nonfunctional; either way, it needs to be replaced. While checking the engine, make sure to inspect the function of the exhaust gas recirculation (EGR) valve; the EGR valve shouldn't open until after the engine is at operating temperature.

Goodbye Ford Auto Hubs; Hello Manual HubsI've owned an '87 Ford Bronco for a few years and I simply don't like the factory automatic locking front hubs. I considered replacing the auto hubs with manual locking hubs from Warn or another aftermarket source. However, I then found out that Warn doesn't manufacture manual hubs for the Bronco because it is equipped with flange-style hubs. Is there a company that makes manual hubs for my Bronco?Dennis StarkOgden, Utah

As you've found, Dennis, Warn doesn't manufacture manual front hubs for your Bronco - at least not in aftermarket form. Interestingly, Warn was the manual hub supplier to Ford on '87 Broncos, so a swap to manual hubs is possible. You can try calling a few Ford dealers to see if they still have the parts in stock. If you can find a set, they're a direct replacement for the automatic locking hubs. An alternative is available from Superwinch. Its aftermarket manual hubs for your Bronco are readily available through any off-road accessory store that carries Superwinch products.

Brake Caliper Boot CampI recently replaced the front disc brake pads on my '93 Ford F-250 4x4 and I noticed the rubber boots on the outside of the caliper pistons were cracked and one was torn. Is this a problem or is it just cosmetic? Should I replace the boots or leave them alone?Clancy Thortonvia e-mail

Those caliper piston boots are indeed important, Clancy, because they prevent dirt, water, mud, and other contaminants from entering the caliper piston and the caliper piston's bore. We seem to remember a Ford service bulletin issued during the mid-'80s that dealt with the boot wear problem. Apparently, the OE boots were manufactured from a compound that wasn't durable enough to withstand the heat generated by the calipers under heavy braking. Ford has long since upgraded the OE replacement boots to a high grade of silicon rubber; the better boots are still available from your Ford dealer, or you can get a new set of boots from a local auto parts store that carries brake parts.

Editor's Note: If you have any questions, comments, rants, or raves, please feel free to contact us at OFF-ROAD magazine, Mailbox, 774 S. Placentia Ave., Placentia, CA 92870. You can e-mail us at joe.mollis.@primedia.com.

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