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| 11/2/08 Track times. https://www.slantsix.org/forum/viewtopic.php?t=32063 |
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| Author: | Shaker223 [ Mon Nov 03, 2008 2:03 pm ] |
| Post subject: | 11/2/08 Track times. |
I was only able to make 3 passes and they were not even full passes. Each time I had a back fire in the top of 2nd or the top of third....not sure why. I can only speculate. AFR was 11.7:1 on 2 of the passes. Not sure on the other temp was 48*f outside no wind 100% 110 octane fuel timing 20* locked 100% meth starting @ 4psi new plugs = rn9yc @ .024" (maybe to wide...didn't have time to regap at the track) to many track delays. A newer Corvette exploded the rear and put gear lube down. They were kicking parts to the side of the track. Old head from last year and old springs ( to weak for 25psi?) 2nd-darys to lean? I have an 87 jet in there now. Best pass was: 1.934 60' 1/8=8.362 1/8mph=89.14 1/4=13.43 1/4mph=84.04 Nice 1/4 mile speed vs 1/8mile speed After thinking about this more. The "backfire" I'm experiencing may just be the intercooler hose blowing off at high boost conditions and making it sound like a backfire. I'm going to scuff the smooth (painted) intercooler pipes and double clamp them as well. I'm also going to put the 340 springs on this head too. Everything else seemed fine. Retooling for maybe 11/23 or 11/30 |
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| Author: | Shaker223 [ Tue Nov 04, 2008 6:54 pm ] |
| Post subject: | |
I did some investigation and the issue is probably the slant six valve springs. On an inefficient setup the pressure ratio can be as great as 3:1.....meaning the exhaust may have as much as 75psi of back pressure (vs my 25 on the intake)on a spring that has maybe 65psi on the seat. |
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| Author: | Dart270 [ Wed Nov 05, 2008 5:47 am ] |
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I have had valve springs go bad on an NA motor and kill perf over 3500 RPM. Nice times and progress anyway! Lou |
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| Author: | slantzilla [ Wed Nov 05, 2008 5:23 pm ] |
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Looks like you're making good steam at the 1/8th. Should be fun when you can get it all the way to the end under power. |
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| Author: | Shaker223 [ Wed Nov 05, 2008 6:20 pm ] |
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Should be interesting if I can get it down the track. Anyone have any small block heavy duty valve springs? Used is fine. I'll have 2 more chances if the weather holds. 11/23 & 11/30 |
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