Darkening original engine bolts...

Special Coupe Frank

Special Coupe Frank

Well-known member
I searched the Forum earlier today, looking for info about recreating the blackish, "Raven" finish on original engine bolts.

Let me say that I am NOT building a "points car", but would like to come close to correct appearance.

I saw some comments about cleaning the bolts ( de-grease, wire-brush ), heating with a torch, then dunking in used motor-oil.

Can someone suggest a temperature to heat the bolts to if I were to heat the bolts in a pan, say in the oven or gas-grille (don't tell my wife!) ?

It would be a lot more expedient ( and controlled ) to heat a batch of bolts in a controlled manner than for me to do one at time in a flame... ;)

Thanks !

Frank
 
I use G-96 gun blueing to darken mine. It does a great job, and as soon as I finish with the blueing I use ATF to oil them and keep the rust away.

I never had luck with Birchwood-Casey, but a guy in our club has made some nice specialty Model A tooling and used BC to darken the parts, and they came out perfect. I must have had a bad jar of the liquid.
 
Special Coupe Frank said:
I searched the Forum earlier today, looking for info about recreating the blackish, "Raven" finish on original engine bolts.

Let me say that I am NOT building a "points car", but would like to come close to correct appearance.

I saw some comments about cleaning the bolts ( de-grease, wire-brush ), heating with a torch, then dunking in used motor-oil.

Can someone suggest a temperature to heat the bolts to if I were to heat the bolts in a pan, say in the oven or gas-grille (don't tell my wife!) ?

It would be a lot more expedient ( and controlled ) to heat a batch of bolts in a controlled manner than for me to do one at time in a flame... ;)

Thanks !

Frank
Click to expand...

Just before red hot.
 
here is the best to use
 

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The raven finish you are looking for is technically called black oxide. If you have a shop nearby that does heat treating and various types of metal plating and finishing they usual have the black oxide process. If you have a sizeable amount they might reprocess them for you. I have tried using naval jelly rust inhibitor which will turn bare steel to a matt black finish. I applied some to my antique tractor splined axle about 10 years ago and it still hasn't rusted.
 
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