General
Information
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Timing Chain Sets
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Harmonic Balancers
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Driveline
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Wheel Studs
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Tech
Support
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| Tunnel Bore Sizes |
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How to Determine Tunnel Bore Sizes
After fitting your standard Rollmaster Timing Chain Set to the engine
you need to pinch the chain with two fingers halfway between the crank
and the cam sprocket on the right hand side. Without forcing or pushing
hard move the chain back and forth and note the amount of movement.
Use this formula:
1/4" = .002" to .004"
5/16" = .004" to .006"
3/8" = .006" to .008"
1/2" = .008" to .010"
These sizes are the amount of the oversize you need to order to obtain
the best possible results for chain fitment.
How to order an
oversize or line
bore timing set
Add to the standard part number the oversize that you determined from
the deflection measurement.
For example, CS1000-006. This informs Rollmaster that you need a small
block Chev set that is .006" larger on the cam sprocket.
Rollmaster suggests that you keep one standard timing set for
referencing each engine type you use.
The sizing of our standard timing sets with an Iwis chain will not vary
as each set is paired for exact centre to centre distance.
This will allow you to maintain a constant relationship between
standard centre to centre distances and line bores blocks.
How does it
work?
When you machine the engines main
bearing tunnel the
distance between the camshaft and the crankshafr can become closer
causing a standard timing set to fot with slack in the chain.
Rollmaster solves this problem by manufacturing sprockets slightly
larger in thou increments. The larger sprockets are similar to engine
bearings being thicker for cranks that have been ground. The result is
the larger sprocket takes up the slack in the distance between the
crank and the cam after machining.
Do not use chains that claim to have smaller pitches as these soon wear
and reult in a poor fitting timing set soon after.
Do not mix and match Rollmaster timing sprockets as these are match
paired. Rollmaster lists factory centre to centre distances for most
popular engines (follow
this link for this
information).
The information supplied here is a guide only. User discretion is
required. |
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