Fixing the Head
Daniel Dempsey
A precision scraper
This page describes a tool a made to fix the coined head damaged by detonation.
I thought I could fix my damaged header quicker with a home made tool than the time it would take to get it to a qualified machine shop and get it back. The tool I designed is a scraper. The concept is that the flat area of the head is a good enough reference surface to guide a fixture. The tool I had in mind would scrape the metal which requires very little power and could therefore be done by hand, plus I only needed to remove about 20 thousandths of material. I started with the parts of a joggling tool pictured here.

The wheels from the joggling tool would keep the blade located laterally.
A small cold chissel was sharpened to use for the scraping blade.

Here's the tool in position. The scrapers depth is adustable. A tiny amount at a time the scraping edge was lowered then many turns were made to scrape away the metal at that depth. Then another slight adjust was made and the steps repeated again and again. It took about an hour to do the one cylinder.

Here's the cylinder after scraping. The coined indentation is gone. Now I'll use either 2 gaskets or a thicker gasket on this cylinder.

By moving the tool from cylinder bore to cylinder bore the same amount of material could be removed from each cylinder.
Checking with a depth guage when I was done showed no more than 1 thousandth between any of the bores.
I wound up taking 0.030". The beginning measurement was 0.575. The end measurement was 0.605.
Using (2) 0.032" head gaskets should put the chambers back in their original position within a couple of thou.