Technical Information

Timing Chain Sets

How to Determine Tunnel Bore Sizes

After fitting your standard Rollmaster timing ghain 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 result in a poor fitting timing set soon after. Do not mix and match Rollmaster timing sprockets as these are match paired. Rollmaster lists factory center to centre distances for most popular engines
Follow this Link for suggested Sprocket Data
The information supplied here is a guide only. User discretion is required.