Painting / blasting valve covers question
04-18-2013, 11:04 PM
#16
Three Wheelin'
I blasted and painted mine with gold engine paint. Came out pretty good. I just spray painted the inside with a quick coat of clear.
Last edited by greg1990964; 11-03-2013 at 01:27 PM.
04-19-2013, 08:54 AM
#18
Burning Brakes
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EDIT: come to think of it I don't think I have ever seen unpainted cam covers on a 964, other than replacement billet covers. Do they look the same, other than the paint thing?
08-30-2018, 11:59 AM
#19
The only media to use would be soda, dry ice, plastic or walnut shells. My friend and go to engine builder has done a few rebuilds of ruined engines as a result of glass beading the inside of valve covers. The media embeds in the (softer and more porous) alloy, and releases after time and heat.
08-31-2018, 09:47 AM
#20
Rennlist Member
Another very old thread. I think your mechanic is mistaken. Read my response to your other post.
08-31-2018, 01:37 PM
#22
Rennlist Member
Don't know Pat I do know many others.
What I do know as a third generation foundry man who's grandfather headed Bendix Eclipse pioneer program from 1930 to the 70's and pioneered Dow metal AZ92 and AZ91 the primary magnesium alloys used for the defense industry and my 30 years or personal experience manufacturing magnesium and aluminum sand castings for most all of your helicopters and aircraft far more complicated than these valve covers, that he might want to rethink his assumption.
What I do know as a third generation foundry man who's grandfather headed Bendix Eclipse pioneer program from 1930 to the 70's and pioneered Dow metal AZ92 and AZ91 the primary magnesium alloys used for the defense industry and my 30 years or personal experience manufacturing magnesium and aluminum sand castings for most all of your helicopters and aircraft far more complicated than these valve covers, that he might want to rethink his assumption.
09-01-2018, 03:33 PM
#23
Don't get me wrong Cobalt, I'm not trying to start a fight over this. I had heard this from more than one source, and considering the surface of cast alloy (porosity??), it seemed plausible to me. That coupled with my tendency to err on the side of caution.
09-02-2018, 08:52 AM
#24
Rennlist Member
It might seem plausible and I agree glass bead, Coal slag (black beauty) or any contaminant in your engine is something you definitely don't want.
Improperly cast magnesium will suffer from Micro porosity also known as micro shrinkage. In general it is not porous as you can see in improperly cast Aluminum. Not the case here. I spent years inspecting both radiographically and fluorescent dye penetrant methods ASNT certified and supplied parts for all sorts of applications and I don't want to get into why they are making assumptions. So please believe what you want.
Glass bead might be the cause of the damage they are seeing, how it got there is debatable.
Improperly cast magnesium will suffer from Micro porosity also known as micro shrinkage. In general it is not porous as you can see in improperly cast Aluminum. Not the case here. I spent years inspecting both radiographically and fluorescent dye penetrant methods ASNT certified and supplied parts for all sorts of applications and I don't want to get into why they are making assumptions. So please believe what you want.
Glass bead might be the cause of the damage they are seeing, how it got there is debatable.