351w head port question
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Junior User
Joined: Dec 2003
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351w head port question
I am building a 351w on a budget that I hope to make around 350hp. I have access to an engine machine shop so I can do any machine work I want, but I need to keep parts costs to a minimum (ie. no buying high dollar heads). The heads I have are from a 1986 engine, and there are smog holes on the floor of the exhaust ports that I want to get rid of. How is the best way to handle these? I have considered driving (or threading) pins into the holes before grinding the runner smooth, but I am concerned that the pins might come out during use. If this is an option, can I use steel pins, or should I make cast iron pins so expansion rates would be similar? Also, I have seen some epoxy material that is made specifically for reshaping exhaust runners when porting, but I also wonder if it would stay put for prolonged street use. How are others doing this? Thanks. Mark.
Senior User
Joined: Jun 2003
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Mark, I preformed this operation once by way of a low tech furnace brazing procedure that was not at all worth the hassle. I set up my heads on a gas grill and after giving the head time to reach about 400F degrees, brazed the air injection ports shut with my oxy/acetylene torch. Although the procedure worked very well and looked like something that cost a small fortune to have done, there was no measurable improvement in performance. Needless to say I was very dissappointed after having sweat profusely for several hours standing over my grill with welding gloves and goggles on while my buddy stood by laughing at me and drinking beer the whole time. I have ported many 5.0 and 5.8 heads since and left the air injection holes just as they are knowing that they aren't going to affect performance. Good luck with the build. 
