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will larger valves help top end bottom or both?

This is a discussion on will larger valves help top end bottom or both? within the Internal Engine forums, part of the LSx Technical Help Section category; I have a 77 camaro with vortec heads with 194/150 valves. with a 525 max lift. I have a 480/480 ...

  1. #1
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    pewter
    99 Trans Am

    will larger valves help top end bottom or both?

    I have a 77 camaro with vortec heads with 194/150 valves. with a 525 max lift. I have a 480/480 lift comp cam with 1.6 roller rockers which gives me a lift close to max.I have thought about getting 202/160 vortec heads.I already have a RPM intake, 750 vac holley,headers,accel Dist.B&M trans,B&M 2200-2400 stall,B&M quick silver shifter and 373 pos. rearend.2.5 exhaust with hooker mufflers. The car runs great but just like all of us I want more.I am not to worried about top end horsepower, but more bottom end torque.will the $800.00 be well spent or stay where I am and live with it.The bottom is good but I want even more.
    Last edited by Street Fighter; 01-06-2012 at 01:41 PM.

  2. #2
    cutting and welding mark21742's Avatar
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    hugger orange
    2004

    Most of the time bigger valves help all across the rpm range, but mostly up top....at any given rpm and lift a bigger valve will allow more air flow

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    Yellow
    2006 Z06 LSX 427 TT Corve

    I would agree, most of the time larger valves will help across the rpm range. There is such a thing of to large of valves and runners that cause the port velocity to slow down and you loss some flow numbers. My 427 TT has 2.250" and 1.625" and I flow 366cfm at 0.500" and 391cfm at 0.600", but at 0.700" lift the heads top out at 398cfm. I've seen guys with the same heads hit over 410 cfm at 0.600" but have 20 or 30 cfm less than me at 0.300"-0.500" lift due to them running smaller runners and diffrent port design. My point is a good ported for your heads can help you get more power down low vs at the top end. Also cam plays into this.

  4. #4
    cutting and welding mark21742's Avatar
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    hugger orange
    2004

    If you can feel the air and be the air you can port heads....if you can't, then it should be left to a professional...plus you need to watchout for the water jacket dips in the exhaust runners

  5. #5
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    Yellow
    2006 Z06 LSX 427 TT Corve

    If your not removing material and just polishing anyone can do that long as they read up on it before doing it. Meaning there is books on how to polish heads, with examples of correct and wrong ways. I've done a few sets

  6. #6
    cutting and welding mark21742's Avatar
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    hugger orange
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    Exactly what extremecorvette said...if your going to try it take some time to read about it and as long as your not going hog wild on them you should be fine...remember, don't get the runners too smooth, I wouldn't go any smoother than 80 grit... I have about 10 hours or so in mine and VERY happy with them.

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