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| 7MM Head https://slantsix.org/forum/viewtopic.php?t=56342 |
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| Author: | CNC-Dude [ Wed Oct 08, 2014 2:48 pm ] |
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Quote: Personally regarding exhaust seat inserts I wish that idea would go away. It is completely unnecessary now. However I realize I am wasting my breath despite many years of experience doing it without. don As for my 7MM combo, i'm using racing valve blanks that are swirl polished and backcut. I'll be using bronze guides. Many aftermarket companies have springs, retainers and locks for 7MM valves nowadays, so it's not hard to find what you need. |
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| Author: | ProCycle [ Wed Oct 08, 2014 2:59 pm ] |
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Quote: Personally regarding exhaust seat inserts I wish that idea would go away. It is completely unnecessary now. Can you elaborate on this? What idea? That oversize valves need larger seats installed? Or that the exhaust seats need to be something special?
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| Author: | Dart270 [ Wed Oct 08, 2014 3:18 pm ] |
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They are saying that the inserts are not needed at all. I have stopped putting them in my engines, and Mike Jeffrey and many others say the same. Just bore the seat to whatever size you want and run it. Actually, the only head I have seen with significant seat recession had the "hardened" seats installed. Unless you like to ping the crap outta your motor or run really hot (220+F all the time), then you should not see recession. I am not saying this will work in all cases, but it seems to be fine for many of us here. Lou |
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| Author: | the_engineers [ Wed Oct 08, 2014 3:32 pm ] |
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The 3.8 Ford valve springs are beehives from the factory. 1.3 at the bottom. 1.1 at the top. Or close to. |
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| Author: | ProCycle [ Wed Oct 08, 2014 3:50 pm ] |
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Quote: Just bore the seat to whatever size you want and run it. Would you do this if you were planning a 350 hp turbo+FI build? Or would you say it only applied to a typical daily driver with a moderate performance increase?
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| Author: | CNC-Dude [ Wed Oct 08, 2014 4:34 pm ] |
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Quote: Quote: Just bore the seat to whatever size you want and run it. Would you do this if you were planning a 350 hp turbo+FI build? Or would you say it only applied to a typical daily driver with a moderate performance increase?As Lou said, you would just cut the seat to the valve size you wanted or needed and run it without seats, regardless of your intended use, street, race or otherwise. |
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| Author: | ProCycle [ Wed Oct 08, 2014 5:20 pm ] |
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It was my understanding that the factory case hardening of the seat area wasn't all that large or deep into the head casting and installing larger valves meant you would go beyond the case hardening. So are you guys saying the hardened area is plenty large enough for big valves? Or is there really no case hardening and the base iron of the head is plenty durable to serve as the valve seat? |
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| Author: | CNC-Dude [ Wed Oct 08, 2014 6:05 pm ] |
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The base metal is plenty durable enough to serve as a valve seat. |
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| Author: | DKD [ Wed Oct 08, 2014 7:15 pm ] |
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Not all that deep ... Stop for a minute and think that over. The seat isn't deep. Mine are always nice and narrow at about .060" on a 45 deg which makes it only about .030" deep eve with a top dress maybe 040" or so. I did my first modified slant in around 1976 for a altered race car. I did one for my wife in 77 for her 1966 cuda which she drove daily in non winter weather and the other two I already mentioned . All of these had oversize valves the first two were modified 360 valves and the last two I already described. I don't know where the cuda is or if it is still going but nothing went wrong with the other three heads. They are still around and still good. what more can one say? don |
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| Author: | the_engineers [ Wed Oct 08, 2014 7:41 pm ] |
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So what's to be made of all the pics and stories of severely recessed exhaust valves? I'm not saying you're wrong, just curious about the conflicting info. |
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| Author: | CNC-Dude [ Wed Oct 08, 2014 8:35 pm ] |
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At some point in time hardened seat may have been necessary like back when lead was first taken out of our gasoline back in the early 70's. But like many things, these issues are corrected, but yet people still can't seem to see past those earlier times when hardened seat were required. One of the more plausible causes of pounded out seats that contributed more than anything is the person sitting in the drivers seat and not keeping their engine properly tuned and maintained. Just sayin', many other things caused sunken seats than just poor quality gas. |
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| Author: | emsvitil [ Thu Oct 09, 2014 4:15 am ] |
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Interesting: http://www.castheads.com/blog/2013/12/v ... w-testing/ Playing with the valve stems might be a waste of time........ |
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| Author: | the_engineers [ Thu Oct 09, 2014 6:04 am ] |
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Keep in mind that's an aftermarket pair of $2500 cylinder heads with sufficient port volume and a performance-optimized port shape. If we had sufficient port volume OR an optimized port shape, half of the discussions on this forum wouldn't exist. That said, the proof will be in the flowbench results. I won't lie, I'll be disappointed if there aren't decent gains to be had. |
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| Author: | the_engineers [ Thu Oct 09, 2014 6:18 am ] |
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I read up on hardened seats after this came up... It's all over the board with no clear direction. Definitely there are examples on each side of the fence. One thing I never saw addressed was oversized valves. Yes, touching up the factory induction-hardened seats is pretty much considered OK, but I can't find any discussions on what should be done when the hardened area is removed.. Here's where I'm at...the factory valve was 1.36". Induction hardening is 0.090" deep. I'm planning to go to a 1.50" valve, leaving 0.020 of induction hardened depth. I will have lost 78% of the hardened area. Chrysler did very few things without research and proof. They had too much money at stake. Given that they went to a minimum depth of 0.090" with their hardening process, I'm inclined to do the same. Unfortunately, it'll mean inserts. |
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| Author: | sandy in BC [ Thu Oct 09, 2014 6:38 am ] |
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Inserts are for those who need a belt with their suspenders..... You risk more than you gain. |
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