Valve Covers '47 Knucklehead

[samsmc1]

I see on page 903 of Bruce Palmers second edition series of books that he states Parkerizing is the correct finish for the valve covers. I'm concerned that the modern day equivalent of what the early manufactures used is very different than todays version. Can anyone tell me what currently available finish is correct on these covers and other hardware on the late knuckleheads.
Thanks
Sam

[otis71]

Manganese phosphate is correct chemical for parkerizing. The best instructions I’ve found are on harleykmodel.com under the technical section.

[samsmc1]

OK - I see various methods of finishing the Parkerizing process. What was the original finish like, gray or more like flat black?
I thought black, but I'm not sure.
Thanks
Sam

[RichO]

More like olive drab.

[BillyBalcer]

No one else said it so I will save you some grief down the road... The bottom covers were actually painted black with the heads. Parkerized first. Parkerizing is actually a trade name for Parker Rust Proof Inc. It is Manganese phosphate and is typically flat Blackish/ dark gray. Sometimes post solution, temp, and prep of the metal can dictate the end color result.

[otis71]

The longer it’s left in the darker and blacker it gets. Instructions say 5 minutes but usually a watchful eye is needed. Cleanliness is essential or it will get splotchy. I usually dip parts prior to parkerizing in muriatic acid then glass bead thoroughly.