Moving Up to a Hydraulic Roller Cam - Engine Builder Magazine
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Moving Up to a Hydraulic Roller Cam

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The advantages of a roller cam include: no need to
break-in the cam on initial startup, the lifters can be reused if you
change cams, the open and close ramps of the lobes are faster, giving
you more torque and horsepower for any given grind, roller cams wear at
a fraction of the rate of standard cams, and roller cams can use the
latest blends of motor oil with out the zinc, so no additives are
needed.

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A few things are different about a roller cam
installation. A standard cam is ground in a way that causes the lifters
to rotate during operation to minimize wear. This design causes the cam
stay in place by itself as the engine turns. The roller cam design does
not need to rotate the lifters, so it will “float” in place during
operation.

To keep the roller cam from moving too much, you need to use
a cam button between the cam cover and the cam gear to hold it in
place, and a Torrington bearing behind the cam gear to keep the cam
gear from damaging the block. You will need to set a camshaft end play
by using shim washers (similar to setting crankshaft end play). Lastly,
you need to make sure that your distributor drive gear on the cam, and
the drive gear on your distributor are compatible.

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Roller cams are
hardened steel, and if mated to a soft iron distributor gear, it would
wear out the distributor gear quickly. Most cam makers press on a soft
iron gear on the camshaft at the factory, so in many cases you need to
do nothing. However, if your roller cam has a hardened gear, the cam
manufacturer usually sells a matching hardened steel distributor gear
for you to use.

If you are retrofitting an older engine that
did not use a roller cam from the factory, you will need to use a retro
fit roller cam and retro fit roller cam lifters. These parts have the
correct geometry to go into an older engine and have their own unique
part numbers. Also, you will need to use shorter pushrods for a roller
cam, and the manufacturer will have the correct length ready for you.
If your engine is newer and has a roller cam from the factory, you will
use a roller cam and lifters that are designed as direct replacements.
Roller cams will work with any rocker arm design.

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Going to a
roller cam upgrade is one of those few times where you can really tell
the difference it makes when you drive. Roller cams are more expensive,
but if you can convince your customer to come up with a few extra bucks, it will really be worth
the investment.

 – Tech Tip courtesy of Summit Racing

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