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Least LSA before PTV clearance issues.

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Old May 18, 2006 | 06:15 AM
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Default Least LSA before PTV clearance issues.

What’s the least LSA anybody has run with stock heads and short block before facing ptv clearance issues. I want to get a cam with 108-110 LSA and with 2-4 degree advance on the stock heads and short block that I have.
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Old May 18, 2006 | 06:51 AM
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P to V clearance issues come more from duration than they do from LSA alone. You could run a 224/228 105LSA cam and have no issue, but you might with a 245/255 116LSA cam. You will get intake valve contact at a specific opening or closing degree number. Same with exhaust. Once you know that number, you can back into the narrow LSA cam you want without worry of valve clearance issues.
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Old May 18, 2006 | 06:55 AM
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well I am running a 232/240 .579/.579 110LSA with stage 2 heads (2.02/1.57 valves) and have no PTV issues and I did not flycut, BUT I live on the edge.
with stock heads you should be ok as long as the duration is not too big
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Old May 18, 2006 | 06:59 AM
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I only had .042" Intake clearance with a 224/224 .568" on a 110 LSA +4 (HEADS MILLED .030). So even with stock heads you would be borderline on what seemed like a mild cam! Checked with dial indicator/checker spring/and with my 55 year old mechanic/racer/engineer.
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Old May 18, 2006 | 07:02 AM
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depends on your duration and how agressive the lobes are.

going 108+2 will be really snug on the intake side. 108+4...I doubt that'll happen at 22x or bigger
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Old May 18, 2006 | 07:02 AM
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As stated, it depends on your duration as well. You really need to measure, as there's no accurate way to calculate it.
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Old May 18, 2006 | 07:06 AM
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Trial and error my man, trial and error.
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Old May 18, 2006 | 02:17 PM
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Yeah I know the best way is to measure, but at $400 a trial....I thought I could benefit from other people exprience on this. I would want to run in the mid 23x, and don't want to loose DCR with the stock chambers that's why I want to run a tight LSA that should help the heads breath and lower ICL.
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