Plug weld valve guide hole

admin

Hi.Re Harley cast alluminun cyl.heads,mostly shovel & painheads.Heads are cleaned real good. .Using 300amp tig with Argon. Heads are preheated to 400 degrees.Always seem to have difficultty with penetration at center of weld.I open guide hole (vee)to approx.double dia.both ends of hole to help with access.First weld is done from rocker side as is easy to get at.Finish weld with tig torch in seat hole and filler fed from ex. port.Makes for nice weld except at center,very hard to get filler to crawl to sides of center when starting.Any tricks or sugestions? Will appreciate any help. I am 75 yrs old and NOT a pro.welder. Have welded many of theses but most end up with a few small voids in center that i would like to eliminate. Am using P&H 300 amp watercooled,very very smooth welder and LOTS of power, Yours,Ben.  PS- The machine work is easy compared to doing a good weld-.- [email protected]
Reply:Ben - first I would like to welcome you to Weldingweb! Secondly, as you found out, cast aluminum is very difficult to weld. What is your preparation/cleaning process? Are you cleaning with a wire brush, die grinder and then using Acetone? Welding cast aluminum is, most of the time, a multi-step/multi-pass process. Make a small root pass, like on a pipe or other thick material, clean and re-grind then brush the area, then re-weld. Cast will contain many impurities and mutiple passes will help. Let us know if that helps.John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:Thanks for reply.I die grind all alum. casting with carbide,finish clean with stainless brush.I have better results with dish soap or gunk and hot water than with acetone???.I preheat to 400.Seldom have any problems with Harley castings. Only ocassionaly have to stop and regrind & reclean. On valve guide hole, hole is approx 1 inch deep,shape is hourglass,5/8 at center,tapered to 7/8-1 inch at outer ends.Hard to get that nice clean flow when starting weld just past center.More argon any help? I can borrow a friends argon and make up a backer (Dam)at other end???? Any other suggestions?? Yours,Ben.