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Discussion Starter · #1 ·
how fine a finish can a person put on the inside of an intake manifold? I know they should be left kinda rough to create some turbulence in the air fuel mixture but how far can you go with them? I have an S&S intake manifold that has some pretty substantial casting flash, should I just remove it and call it good or can the actual runners be smoothed alittle.
Also, the intake is marked 158, what does that part # signify?? thanks-
 

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I took the casting crap out of my Super E intake. I left it rough but just took down the "lumps" that altured the flow.
Dan said:
how fine a finish can a person put on the inside of an intake manifold? I know they should be left kinda rough to create some turbulence in the air fuel mixture but how far can you go with them? I have an S&S intake manifold that has some pretty substantial casting flash, should I just remove it and call it good or can the actual runners be smoothed alittle.
Also, the intake is marked 158, what does that part # signify?? thanks-
 

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You can take it out about as far as you want & still have a smooth transition where it meets the head.

As far as polishing, Look at the way the gas goes into the head & how it hits the valve head.

For a even gas charge into the cylinder I always rough up the bottom to slow down the gas (gas would get there first it's closer) and polish the top of the manifold to help it speed up (gas would get there last it's farther), If you can do the same to the head port even better.

 

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Generally, on a "polished" intake or head, it's sanded down to an 80 or 120 grit finish.
 

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Discussion Starter · #5 ·
Bugman - thanks, that is what I was looking for, just didnt know how to ask it correctly. think I'll knock the flash off and hit it with 80 grit.
 
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