These specially impregnated forged stainless valves have proven to have superior wear resistance than hard chrome or electrololysis nickel plating. When used with C630 bronze guides and properly installed and finished, much tighter tolerances than factory can be used successfully for quieter operation, less friction, and much longer service life.
These guides are not finish sized, and must be honed to size after installation to provide correct clearance. Recommended clearance in aluminum heads are as follows:
Intake valve to guide clearance: .0010"
Exhaust valve to guide clearance .0015"
These clearances can be easily obtained by finish sizing both intake and exhaust guides to .3115" as the exhaust valve stem diameter is .0005" smaller than the intake. Because C630 bronze guides are very hard, it is recommended that they are finished with a rigid mandrel type hone such as a Sunnen® P190. These recommended clearances are offered in conjunction with a thin film of moly type assembly lube on the stem on installation, the assumption that the guide is finished straight and true, and that the SEAT IS RECUT TO BE CONCENTRIC WITH THE GUIDE CENTERLINE.
If you find that you need an oversize guide PLEASE STOP and contact the shop. We will exchange for the oversize you need at no additional cost.
Machinists note: Our method of sizing these guides is using a P-180 Sunnen Honall with PK-10 adapter, BL10-308AS mandrel, with L10J69 stone.