Crinkle Paint removal on valve covers...best method

[Miranthis]

Redoing my commando Valve covers. i have been using a mild wire wheel to get the paint off in the bulk of it, BUT i am now getting near the aluminum fins that are are bonded on the steel cover. Doing the refurb without removing the fins. is it ok to use chemicals, or am i just masking the crap out of the aluminum and being very careful. What is the best method to get that last bit off?

Jeff

 

[413]

Stripper will work, do not get it on the aluminum. Not a drop, it may stain it and it won't come back out.

 

[4spdragtop]

Ive redone Commando vc's a few times, I always tape off the fins. Worth every second you invest into masking.

 

[toolmanmike]

Leanna would remove the fins and blast the covers. She said the fins are attached with silicone adhesive. Heat will soften it so they can be removed.

 

[slantsixdan]

Hats off to Leanna, RIP

 

[RustyRatRod]

Hats off to Leanna, RIP

I know that's right. May she rest in peace. That was a loss to the entire hobby and a loss of a great friend.

 

[Miranthis]

Leanna would remove the fins and blast the covers. She said the fins are attached with silicone adhesive. Heat will soften it so they can be removed.

Without her, or someone of her caliber to fix a mistake, I am not removing the fins. Too risky. The mastic is rock hard and I cant be sure I can accurately reproduce the factory hold even if a jig will let me do position.

I have them masked, but just wondering if the paint removal should be mechanical or chemical that close. Sounds like mechanical and hand powered, not power tool.

 

[RustyRatRod]

Without her, or someone of her caliber to fix a mistake, I am not removing the fins. Too risky. The mastic is rock hard and I cant be sure I can accurately reproduce the factory hold even if a jig will let me do position.

I have them masked, but just wondering if the paint removal should be mechanical or chemical that close. Sounds like mechanical and hand powered, not power tool.

Take them somewhere and have them soda blasted. Or do it yourself.

Soda Blaster

 

[RustyRatRod]

Without her, or someone of her caliber to fix a mistake, I am not removing the fins. Too risky. The mastic is rock hard and I cant be sure I can accurately reproduce the factory hold even if a jig will let me do position.

I have them masked, but just wondering if the paint removal should be mechanical or chemical that close. Sounds like mechanical and hand powered, not power tool.

What's the fear? Whatever the bonding agent is, is sixty years old. It doesn't last forever. I'd ease a long gasket scraper under them carefully and get them off, blast the covers and replace them using a high temp RTV. They'll still be there 60 more years from now and you don't have to worry about the old stuff letting loose. Dang man. People who put their pants on one leg at a time just like you and me glued those things on. It's not some alien magic no one else knows how to do.

 

[Miranthis]

What's the fear? Whatever the bonding agent is, is sixty years old. It doesn't last forever. I'd ease a long gasket scraper under them carefully and get them off, blast the covers and replace them using a high temp RTV. They'll still be there 60 more years from now and you don't have to worry about the old stuff letting loose. Dang man. People who put their pants on one leg at a time just like you and me glued those things on. It's not some alien magic no one else knows how to do.

I get (and respect) what you are saying, but from a material analysis standpoint that original mastic does not behave like any RTV that was available in the 60s and not even much like a modern one. Not wanting to fight over it, but there is no evidence I've found that Chrysler used black RTV silicone to bond the 273 Commando valve cover fins in 1965–66. While RTV silicones existed industrially by then, they were not yet the common black, oil-resistant automotive gasket makers that appeared years later. More importantly, the original adhesive found on unrestored covers is, by all the reports i can find,a hard, brittle black mastic that chips and fractures rather than remaining rubbery like cured RTV.

Chrysler also serviced these valve covers only as complete assemblies, so no service literature that I can find identifies the adhesive, and the fins were almost certainly bonded by the supplier before the covers reached the assembly plant. Without a surviving vendor specification or laboratory analysis, no one can honestly identify the exact chemistry, but the physical characteristics are far more consistent with a thermosetting structural adhesive (epoxy/resin mastic) than with silicone RTV. I mean, most folks cant get them apart with making a blood sacrifice to Jobu.

Modern black RTV may work as a restoration adhesive once yiu get them off, but that does not make it the material the factory originally used, or even the best replacement. I am just not comfortable with relying on off the shelf black RTV, at least when the actual expert, who would stand by her work if it went wrong, is sadly no longer with us. I just am not taking the risk when my originals are still solidly attached.

That was my thought process in asking about how best to strip the black around them without damage.

 

[RustyRatRod]

I get (and respect) what you are saying, but from a material analysis standpoint that original mastic does not behave like any RTV that was available in the 60s and not even much like a modern one. Not wanting to fight over it, but there is no evidence I've found that Chrysler used black RTV silicone to bond the 273 Commando valve cover fins in 1965–66. While RTV silicones existed industrially by then, they were not yet the common black, oil-resistant automotive gasket makers that appeared years later. More importantly, the original adhesive found on unrestored covers is, by all the reports i can find,a hard, brittle black mastic that chips and fractures rather than remaining rubbery like cured RTV.

Chrysler also serviced these valve covers only as complete assemblies, so no service literature that I can find identifies the adhesive, and the fins were almost certainly bonded by the supplier before the covers reached the assembly plant. Without a surviving vendor specification or laboratory analysis, no one can honestly identify the exact chemistry, but the physical characteristics are far more consistent with a thermosetting structural adhesive (epoxy/resin mastic) than with silicone RTV. I mean, most folks cant get them apart with making a blood sacrifice to Jobu.

Modern black RTV may work as a restoration adhesive once yiu get them off, but that does not make it the material the factory originally used, or even the best replacement. I am just not comfortable with relying on off the shelf black RTV, at least when the actual expert, who would stand by her work if it went wrong, is sadly no longer with us. I just am not taking the risk when my originals are still solidly attached.

That was my thought process in asking about how best to strip the black around them without damage.

Who's fighting? Do it your way. Just remember you did ask for help.

 

[mopowers]

Why not just mask them up and use stripper?

 

[Firstblood]

I've refurbished 2 sets in the last year, removing the aluminum fins before paint.
Since you don't want to remove the fins, I would use the chemicals and try a small wire brush to remove the paint.

 

[Miranthis]

I've refurbished 2 sets in the last year, removing the aluminum fins before paint.
Since you don't want to remove the fins, I would use the chemicals and try a small wire brush to remove the paint.

View attachment 1716572916

When you removed them, what did the original mastic look like? Hard and brittle, or still somewhat flexible? Two big dollops each side or one? Centered. Bonded to thr bare steel or over thr crinkle paint. Did you make a jig for reattaching them correctly? For avoiding damage did you use regular blue masking tape or something else on the perimeter of the fins?