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Author Topic:   File fit rings, and ring end gap???
Speed Racer X
Dirt Full Roller

Total posts: 61
posted November 14, 2002 09:44 PM
We are getting to build a .030 over 350 block with a 3.750 stroke crank and domed hypereutectic pistons. The piston require 1/16, 1/16, 3/16 rings. My question is are the file fit rings worth the extra money and time? What ring end gap should we run on a 4.030 bore with the hypereutectic pistons? Thanks!!!

Dirt Freak

Total posts: 273
posted November 15, 2002 06:04 PM
Hey racer X, BE SURE to follow the manufacturers instructions! I run Speed Pro's which are gapped about half what Kieth Blacks are. A lot of guys around here would gap the KB's the same as any othe piston and when the motor would warm up, the ring would expand and jerk the top off the piston! I kept hearing that they were junk until I learned that they were improperly fitted. FOR SURE call the mfg. and take their advice!

Dirt Maniac

Total posts: 128
posted November 18, 2002 06:45 PM
You can also get piston to wall clearance and ring gaps for the KBs here:

Dirt Freak

Total posts: 353
posted November 19, 2002 12:27 PM
If you had a fresh bore on your block and it was honed exactly for your pistons then you prob would not notice much difference between the file fit and standard gap rings. If you have a block that has some wear then the file fit rings give you some room to adjust to the oversized cylinder and still be able to keep the recommended ring gap.

Like the others said though make sure you check with pistons suppliers about what they recommend for gaps before deciding. Just like the case with KB you have to open up the top gap so you would have to file standard gap rings too.

Dirt Maniac

Total posts: 122
posted November 20, 2002 12:56 PM
Should be between 16 and 18 thousandths.

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