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| Whats your valve combo? https://www.slantsix.org/forum/viewtopic.php?t=50564 |
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| Author: | Turbo Toad [ Thu Dec 13, 2012 11:14 pm ] |
| Post subject: | Whats your valve combo? |
I'm getting ready to start building a back up motor which will ultimately be my main turbo motor. And I'm going to build and port and polish and install larger valves on a spare head. The head I have now is hoged out good with a set of ss 1.70 intake and 1.44 exhaust valves and im curious to see what is the largest size valve combination I can put on a long rod motor bored..80 to.100 over This is a low compression motor that won't have any mill work done to the surface expect being cleaned up. Any and all comments are welcome and appreciated Aaron |
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| Author: | Dart270 [ Fri Dec 14, 2012 3:00 am ] |
| Post subject: | |
For that bore, you probably do not want to go above 1.76/1.50 - valve shrouding. Some folks have gone a bit above 1.80/1.50, though. For economy and availability, 1.72/1.50 SB Chev valves or 1.78/1.46 SB Ford valves are good choices. Lou |
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| Author: | Rug_Trucker [ Fri Dec 14, 2012 4:13 am ] |
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I was looking at some Mopar valves from a set of #302 SB head. Stainless in a turbo motor would be nice! |
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| Author: | robertob [ Fri Dec 14, 2012 8:40 am ] |
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Man after looking at the combustion chamber I can't imagine you get much additional breathing out of larger valves, there's so much shrouding. I would like to see flow numbers of a head bolted down with larger valves. |
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| Author: | robertob [ Fri Dec 14, 2012 8:41 am ] |
| Post subject: | |
Just realized Lou said the same thing, and if he says it I am sure it is true! Has anyone tried offsetting the intake guide inward to squeeze in a larger valve with a stock-ish exhaust? Something like 1.80 with a 1.45 exhaust valve? Then use a non-dual-pattern cam, instead of the commonly used longer-duration intake. |
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| Author: | Reed [ Fri Dec 14, 2012 8:49 am ] |
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I believe the absolute largest valves you can put in a slant head without modifying the combustion chamber are Ford 300 valves. |
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| Author: | Dart270 [ Fri Dec 14, 2012 11:23 am ] |
| Post subject: | |
A few people have moved the intake valve over, and flow does improve. I have been meaning to try this. IIRC, Cameron Tilley had a head that was 1.84/1.40 or something in that neighborhood that flowed ~ 230 CFM intake. That motor made 350 HP @ crank on race gas, 12:1 NA motor. Lou |
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| Author: | slantzilla [ Fri Dec 14, 2012 3:46 pm ] |
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To unshroud the intake you relieve the chamber next to it. Pictures of that have been posted here before. I have seen claims that people have put 1.88 intakes in, and they make tremendous flow numbers on a bench, but I have never seen one of those motors ever run worth a crap. The LS-1 uses a 2.02 intake and a 1.50 exhaust. I have been thinking of following that ratio on the next head Mike does for me. 
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| Author: | Turbo Toad [ Fri Dec 14, 2012 5:21 pm ] |
| Post subject: | |
Has anyone tried some 7mm valve stems also I'd kind of like to go with a 1.55 or 1.6 on the exhaust side it seems to me that's were a turbo motor would benefit from please correct me if I'm wrong. |
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| Author: | Turbo Toad [ Fri Dec 14, 2012 5:23 pm ] |
| Post subject: | |
I'm also interested in moving the intake side does anyone have a link? This is the first I heard of this Aaron |
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| Author: | WagonsRcool [ Sat Dec 15, 2012 6:01 pm ] |
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For my last build I went with the SB Ford valves - you get 11/32" stems. |
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| Author: | Will [ Sun Dec 16, 2012 4:02 am ] |
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Like Lou said, 1.80 1.50 11/32. Easy to get. Will |
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| Author: | Turbo Toad [ Mon Dec 17, 2012 6:12 pm ] |
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So I've been looking at some different valves what's a standard I/E measure from end to end? Also I started to work on the head if anyone is interested ill get some pics up Aaron |
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| Author: | Turbo Toad [ Fri Jan 11, 2013 8:54 pm ] |
| Post subject: | |
OK so I believe I've decided to try and run some 7mm titanium valves, there's a shop here locally that will cut some down to my desired size. Which means I'm going to have to change out my guides what's recommend stainless or bronze? Also I read in a different post that there is a certain thickness of hardened valve seat that's needed when installing larger valves? I'm almost done with my port work but I want to get thehead into the machine shop and have the guides installed and the seats cut before I finish the port work. One last question when getting a head flow tested do you do that before final assembly? Thanks all Aaron |
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