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I am going to have a 5 angle valve job done soon and I was looking at the exhaust ports. I don't need a full port job but just a little to clean up right inside the opening. What I need to know is if I can grind some of the bump off that is reinforcing the spark plug threads and the ridge on roof of the port where the casting was made for the emissions. If anyone can tell me if this is safe, I would well appreciate it. Just want to clean it up a little better than it is now. Thanks for looking
Bud
 

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Go to a book store. You can find a book on hopping up the Mustang. It will have a section on the heads. It will walk you through the whole deal on cleaning up the heads. Worth every penny.Roger
 

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There isn't much to be gained at the plug bump, I would avoid it, where the heads can use so work is around the bottom of the valve guides, and then a slight opening of the throat when you have your valve job done. In fact, a good valve job and blend to the bowl, and some clean up of the guide bosses will get you significant gains with little risk

Be sure you "match" the roof and floor of the exhaust port to your headers, and realize, if you run early or CJ ports, you won't be able to get there. It doesn't have to match the exhaust perfectly, in fact, I like to leave a little step, in theory it may help reversion. If you are going to run stock manifolds, I wouldn't even worry about it, because they will steal more flow than you can gain.

You didn't ask about the intake, but, if running a medium riser intake (RPM, etc) gasket match the intake side to a 1247 or Mr Gasket 202A, if running a low riser intake, match the roof and sides to a low riser gasket and roll back the floor lightly just so it isn't a sharp edge, don't gasket match the bottom, all the flow should stay on top of the port
 
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