Universal Fit, .502" O.D. Guides

Hardened Cast Iron Valve Guides, 5/16" X 2.281" Long, Sold in Quantities of one.

Order quantity required. Enter quantity 1 for 1 valve guide, etc.

Hardened Cast Iron guides have a spiraled ID which goes through the guide around 75% of the length.

Hardened guides require a few extra procedures during installation but once properly installed and when mated with hard stem valves, (chrome and nitrided [melonite]), their wear resistance is outstanding!

Hardened guides should be given a carbon cut out on all exhausts. This is done on the chamber side of the guide, it is needed only on the exhausts.

Intakes get a chamfer on both ends with the exhausts getting a chamfer on the top side only. Carbon cuts are commonly done using a guide liner cutter/reamer or a reamer for oversize valves. .015"-.030" over works fine.  Just cut into the guide around .150"-.225" deep.

Hardened guides should be cleaned with a spinning nylon brush and cleaning solvent before assembly. Proper cleaning is very important. Any hardened debris hiding in the spiral groove can lead to galling and other forms of guide failure.

Many years ago,  before hardened guides became more common, we had to learn the best ways to use hardened guides.

We're here to offer these tips to aid in your successful installation.

Once properly installed and prepped, hardened guides have a very high resistance to wear.

This type of guide is used in heads which have "integral" guides. This means the guides are part of the casting and are not removable.

Heads are set up in a "Seat and Guide Machine" and each guide is core drilled, then reamed to .500".

Guides are then pressed or "driven" into place. Any extra length is then spot faced to fit.

In our shop, after the guides are installed, we take a .500" valve seal cutter to clean up any old remaining original guide material from the seal side of the guides so .500" Positive seals could be installed.

If needed, guide inside diameters are then fitted by honing w/ Sunnen tooling.

     Specifications:

• .502" Outside Diameter
• 2.281" Overall Length
• .312" Inside Diameter
• Spiral ID: YES
• Plain ID: NO
• Material- Cast Iron, Hardened
• Manufacturer- Precision Engine Parts
  
• Sold in singles, enter quantity one for one valve guide.