I have some heads that a buddy of mine tried to clean with throttle body cleaner and now they are almost white. What can I use to clean them and get them back to the bright aluminum color. He only did one before we caught it. Not his fault as I didn't know it would do it either.
I used scrub pads and soap and water. It will take some elbow grease to get them looking like new. For the valves I just ran them under my wire wheel on the bench grinder. I spun them in the direction of the swirl polish and it didnt effect it at all. If you can, fill the sink or tank with hot hot water and let them sit in it for a while.
1989 Mustang LX/Dart 428w/Turbonetics 88mm/AFR 225's/Solid Roller/Glide/FAST XFI -Nearing Retirement!
2011 FFR Type 65 Coupe (build in progress)- Dart 428Twin Turbo, Fast XFI, T56 - Just a street car!
2012 STI - Cobb stage 1 tune daily driver
If you're having a hard time with the cast parts of the head, you can use a fine, small wire brush chucked into a drill. I use this on intakes and it works surprisingly well. It doesn't leave scratch marks, but gets the aluminum looking like new. I wouldn't use it on machined surfaces or inside the valve cover area, though.
'84 LTD LX - Whippled 365 SBF with a glide and 3.08 gears. Driven to and from the track without even changing tires. 10.19 at 136 on 93 octane and still tuning...
I have used paste type paint remover to get some of the varnish and carbon off of aluminum heads. It won't effect the metal and you can leave it on as long as it takes to loosen all the grundge.
On cast iron I would use oven cleaner. You can use it on aluminum too but you will stain the aluminum so I don't recommend it. I also have a blast cabinet that I then glass bead in to get the heads to that new cast look back.
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DD '12 VW Jetta TDI, Race car '87 ITA 16V Scriocco
Cars owned: '86 Mustang GT, '92 Mustang LX, '93 Mustang Cobra "R" #58