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Supreme Being
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| John, I did not in any way take offence. I value your knowledge which is far more extensive than mine. I certainly do not intend to offend you or anyone else. I have a certain set of personal criteria for this engine. It is certainly not what others will want. I just want to build the best product I can that fits these guidelines. My application is a very mild street application. The thought process I am going through may be applicable to others that have a different set of parameters. Ted has obviously has pushed the limits on extreme performance with his EMC entry and the dragster engine. My main thrust is to explore the limits of the camshaft/lifter interface. Since John has adresses the airflow issues this appears to be the next problem in building an exceptional Y.
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Supreme Being
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John Mummert 5/22/2010 A lot of people would argue that building aluminum heads for a Y-Block is not a wise thing to do. I chose not to listen to them. There was/is a certain amount of insanity involved in this project. I can tell you that the only SpeedSmith left in the project is the name on the sales receipt. Everything else is Mummert. I have personally seen flow bench results that are pretty impressive. And you can carry one around the garage in ONE hand. The amount of work time and investment John (and son Jeff) have put forth is tremendous. We're talking two guys in a small shop, NOT a large corporation with limitless capital and resources. Congrats are in order, the finished product will be worth the wait, I hope that we all apreciate this effort.
Frank/RebopBristol, In ( by Elkhart) 
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Supreme Being
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| John deserves a huge amount of credit, both for his heads and intake. The old heads and intake were corks in the Y performance bottle. I doff my hat to John and his son for the effort and heart ache this project has caused. He is on the edge of sucess here, and I hope he sells all he can produce. Just from the bits I have seen in print There has been a tremendous amount of thought done for accomodating the future with these heads. They will be the rock on which the future of the Y will be built.
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Forum Newbie
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| I don't see any problem with exploring the limits of camshaft right up until the point where you do more harm than good. The Y-block does have a large lifter for a domestic V-8. Things you will want to keep in mind when trying to push the limits of lobe velocity are. 1. Chamfer on the edge of the lifter. More chamfer less useable lifter face. 2. Lifter bore centering over the lobe. The farther off center it is the less useable the lifter face becomes. 3. Acheivable nose radius on the cam. Short duration, high lift cams will have a small nose radius. Making them RPM limited. They almost always get pitting on the nose of the lobe. Not neccesarily going flat but just but just tramatized do to high spring rates with high velocity lobes and small contact area, nose to lifter. 4. Spring rate, rate in a spring is stored available return energy. Two spring set ups can have the same open pressure but one can have considerably less return energy. Example. 120# on the seat and 320# open @.500" 200# gain over .500 lift is a 400# rate per inch. This will have more nose control than a lower rate setup. Say 145# on the seat and 320# open is a 175# of stored energy over the nose. 350# rate per inch 5. Lobe dynamics are the biggy on the list. The main reason is that these harmonics get transfered through whole valvetrain. Especially your pushrods. Pushrods have been one the biggest culprates to unstable valvetrain and many times the springs get the blame. Don't get me wrong you can be under sprung. Like I said earlier pushing the limits of the lifter face can done safely as long you are looking at everything much closer. In the end it all call comes down to valve events. More modern attempts have been tamer lobes and more rocker ratio to acheive the desirable valve events When done right they both work well.
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Supreme Being
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| There is no problem exploring this area, except the discussion is about the heads. We should probably get Ted to move this to TECH or Racing. The valve events and geometry can be discussed there. It is an area that can be explored now, there wasn't much point prior to the new heads since the port airflow stalled at relatively low lifts and rates with the iron heads. The Mummert head changes the ball game. I think it's safe to say the limits of the iron heads have been explored to death by John Ted and others. None of the cam timing, profile or lift theorys help much without ports that carry increased airflow.
Frank/RebopBristol, In ( by Elkhart)
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