351W head question
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351W head question
I posted this question on the 351w forum and received a couple of good responses, but I wanted to repost here to see what more people have done. Here's the 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.
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.
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From: south louisiana
Those holes you're referring to are in the port roof, not the floor. And as Torque1st said, just grind the bump flush with the port and forget about the holes. Just make sure you plug the other end of this passage at the end of the head. It's open at one end and has a threaded insert in the other. The open end was to the rear of the engine, the threaded end was up front. You can use either head on either side of the engine, just as long as the front end has the threaded insert and the opposite end is plugged.
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Why is this post in the 351w forum? I had posted this question here earlier, and only received a couple of responses, so I posted it in the performance forum to get additional advice, and now I find it moved. Since when can't I ask a question about a 351w in the performance forum? Please put it back where I posted it. Thanks. Mark.
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From: Bend,OR
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Did they still have the emissions holes? Do they flow better? What makes them better?
Also, for a build like I described, what sort of work should I do to the heads? If I grind on the runners, how much material should I remove? I have been considering going to 1.94/1.60 valve sizes. Should I do that or stay stock size? Thanks. Mark.
Also, for a build like I described, what sort of work should I do to the heads? If I grind on the runners, how much material should I remove? I have been considering going to 1.94/1.60 valve sizes. Should I do that or stay stock size? Thanks. Mark.
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From: Bend,OR
yes the e7's flow better then your current heads stock. add a little port work and some polish on the exhaust side with a 3angle valve job and your set. is this your first time doing this type of work?
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From: Fleming Ga
Look on my web site for a howto on porting the windsor heads. http://www.armstrong.edu/ron/auto/e7.html