How To - Lapping Engine Block and Heads

Parts Needed, Tools Needed, Step-By-Step, Notes

Topic:                           Here's how you lap mating surfaces

Expertise Required:      Intermediate

Estimated Time:            About an hour for a block, 1/2 hour for a cylinder head

Parts Neeed:               You will need the following parts:

      • Glass Surface (old 1970's furniture had these)
      • Water-based Valve Grinding Compound
      • Lots of wiping cloths

Tools Needed:             You will need the following tools:

      • Screwdriver to open valve grinding compound can? Newer containers have a screw top

Step-By-Step:             If you are not going to have the block decked, then take the time and LAP it. This will ensure that you have a nice, clean and flat surface for the head gasket to seal against. Same goes for the cylinder head - if it's not headed off to the machinist. Here's some lapping pics.

Continue the lapping process until the surfaces have a completely dull finish. Any low spots will be immediately visible. Here's one here:


After a while you'll end up with a good finish like this:

Notes:                For a how-to guide on Motor Preparation - please see this article.  Motor Prep




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