Finishing valve seats on today’s multi-valve heads

Use a more gentle approach when grinding valve seats
One of the most frequently asked questions on our tech line today is: “What is happening to my valve seats? I’ve tried everything! A new stone, stone holder, pilot and even a new dressing diamond but I can’t achieve seat alignment.”

The problem lies more on technique and the power source than in the tooling. Although it’s probably not time for a complete “overhaul” of your equipment and technique, you may need to re-evaluate and make a few changes in the way you’re used to doing things. This is probably one of the easiest and least costly changes you can make to your shop.

The techniques we have used over the years have worked great on older, large-valved engines. However, some of today’s newer engines with the tiny valves require new techniques and new equipment. For years we have been able to “bully” our way through, but now we must learn to hold back and provide a more gentle touch.

Today’s new heads are “dimensionally challenged.” Smaller valves require smaller pilots. The pilot area that aligns the newer heads are almost always one half to one third the diameter of its predecessors. This small pilot size allows more deflection, throwing our work off-center. In the past, we have unknowingly relied on our large diameter pilots for support but pilots are meant for alignment only.

Remember…

  1. Be gentle! Don’t push or crowd the valve seats. These smaller seats cannot be bullied like we’re used to doing on their larger counterparts. Work must be kept closer to your body, do not work at arm’s length. You’ll have much more control over tooling while reducing deflection and fatigue.
  2. Eliminate side pressure. Use a sturdy head stand like our HH-200 (see pg. 65 in our catalog), an ultralight air hose and light-weight, straight grinder such as our AG-4500 (pictured). 100% of its weight is evenly distributed over the seat. Using an angle grinder motor for your power source is cumbersome and off-center. Since we are grinding valve seats on-center, we should drive our seat grinding tooling on-center as well.
  3. Use a free-cutting stone. We recommend our Nickel-Chrome valve seat wheels for small valves. These stones virtually eliminate the need to push or crowd the valve seat.
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