Exhaust manifold surfaces smoothness question

[rebars1]

I am getting ready to install new manifolds, spacers and risers in my Chriscraft Scopion 230. I have removed the paint from the mating surfaces where the gaskets go, but there are some mill or machining lines remaining in the steel from the manufacturer. Do those need to be smoothed/honed out as well? I plan to install them dry.

 

[NW Redneck]

Re: Exhaust manifold surfaces smoothness question

They should be fine. Generally, unless they're deep enough to catch with a finger nail you're ok. They're not under alot of pressure like cylinder heads. When I re-did my gaskets I just made sure the surfaces were clean (no old gasket material) and dry (no oils) and they seal fine.

 

[Boomyal]

Re: Exhaust manifold surfaces smoothness question

I always take a good flat file and run it around on several of the port surfaces at the same time.

 

[bruceb58]

Re: Exhaust manifold surfaces smoothness question

According to the instructions that come with Volvo riser gaskets, you should use 80 grit sand paper with a sanding block to smooth the two surfaces.