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train. A worse problem is that excessive lash leads to accelerated wear and here again,
the bigger the gap, the faster the rate of rate. A loose fit of your cam gear also means
the engine is going be noisier than it should.
CASE #2 - TOO TIGHT... MAYBE?
When you can't feel any lash at all it does NOT automatically mean the thing is too tight.
You could have lucked out and gotten a cam gear that is a perfect fit. Here's how to find
out.
Press lightly on the #2 bearing of the camshaft while rotating the crankshaft COUNTERclockwise. If the gears are jammed the reverse rotation of the crankshaft will lift the
cam shaft up, right out of its bearings. Be careful here. There will be some lift even with
a loose fit which is why we put finger pressure on the center bearing. But if the thing is
truly jammed the effect is unmistakable. It will toss the cam right out of there.
So... is it too tight? You're the Mechanic in Charge. It's your decision. If you need more
data, go ahead and try the next smaller size of gear. Now repeat the counter-clockwise
test. You should feel some lift. Compare it to the amount of lift you felt with the first
gear. This should give you enough information to decide if the first gear was really too
tight.
CASE #1 - YOU FELT SOME LASH
How much did you feel?
The sensitivity and precision of our sense of touch varies from person to person. All we
know at this point is that the gears were not jammed AND they were not loose enough
to make a clacking noise as we rocked them back and forth.
To find out how much lash you're dealing with you'll need to set up your dial indicator.
You want to measure the lash directly opposite the point where the cam's gear engages
the driver gear, that is, over near the bottom of the crankcase. Rig your clock with a
pointed pallet so as to make contact with the middle of one of the gear teeth. You need
to take the angle of the helical cut into account when you mount the dial indicator; just
cant it at an angle so as to be perpendicular to the plane of the tooth.
When you've got your clock set up, rocking the gear with finger pressure should give you
a repeatable indication on the scale. Anything up to four thou (.004) is pure gold.
Anything over .006 sez you can do better by trying the next larger size.
THAT'S IT?
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