I copied the E-tool idea from one of David Vizard's books; it's accurate and works well.
Used 5/16 diameter steel rod. Vertical leg of "E" is 10 inches, each horizontal leg of "E" is 5 inches. The center horizontal leg is 5 1/2 from one end. The free-swing leg is 10 3/4 inches, with a 3/8-16 NC coupler x 1 3/4 long welded at one end. The adjuster nut/bolt is 5/16-24 NF, the bolt is 3/4 inch long. I put a drop of blue loctite on the adjuster threads so it will maintain a setting. Not much welding to do, keep the "E" flat so it lays flat on a table.
Can be used to check port wall casting thickness. The 360 head in the photo had 0.20 thick casting at the pushrod pinch hole.
To set a pushrod pinch wall thickness, place a feeler gage at one end as in the photo, turn the adjuster bolt so gage has proper 'drag', then use carbide cutter or such to remove a little metal at a time from the push pinch, checking with E-tool between cuts until adjuster bolt contacts middle leg of the "E". The wall thickness is now what ever your feeler gage setting was.
Also works well for reducing head bolt bump-outs in the intake port walls like on Edy magnum heads. I reduced the bump to 0.10 thick on my heads.
