I am bringing a set of rams horn manifolds to be ceramic coated tomorrow morning. I was contemplating smoothing out the parting lines, so they have a cleaner look. I had originally thought about it because one has a strange line that looked like a crack but had to have been a flaw in the casting. I wanted to take off some material to make it look better, but I didn’t want to take off too much. Should I leave the lines for originality, or just do what I want to improve the appearance? Should the mounting surfaces be coated also? I have tried them up already.

Thanks,
Soffian

Soffian Adam
Jamestown, NY
59 F100, 55 Club sedan

Grinding the parting lines so they are smooth for appearance purposes will not be an issue.  I have had several cast iron exhaust manifolds ceramic coated over the years and did not specify either way about coating the flanges but the firm doing the coating did not coat the flanges.  I suspect coating the flanges would make them irregular and harder to seal if the ceramic is laid on too heavy.  This would be a good question for whoever is doing your coating.

On the flip side of this, whenever I have headers coated, the flanges are also coated as well as the insides of the tubes.  These are on race cars and while some leakage might be expected, with gaskets or a thin film of hi-temp RTV all has been well.

Lorena, Texas (South of Waco)

Thanks Ted. I figured since the manifolds are fairly short, they should have no problem coating the insides. I’ll ask about the flanges and will clean up the parting lines.

Soffian Adam
Jamestown, NY
59 F100, 55 Club sedan