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Old 02-17-2011, 01:42 PM   #1
Bdeliman
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Default Maximum lift for stock LT1 valve springs

What is the maximum lift for the LT1 valve springs. In the Chevy Power manual, it specifies that these valve springs are 135 lbs at 1.72 inches, and 290 lbs at .5 lift. I'm looing to go right around .5 inches of lift.

Bill Deliman
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Old 02-17-2011, 01:58 PM   #2
TheSkunkWorks
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As actual installed heights may vary from spec, you should check how much coil bind clearance you have at a known lift, and add the difference to that lift less 0.060" (typical suggested minimum coil bind clearance). The resulting total should be pretty close to the max lift possible. Yep, I'd check all 16 if you're cutting it close.


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Old 02-17-2011, 04:21 PM   #3
LT1driver
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springs are cheap and if changing cam you NEED TO change springs...good advice, good insurance against problems..in long run it is your choice and follow advice about checking coil bind if you are buying new chevy springs.
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Old 02-17-2011, 04:25 PM   #4
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Why would anybody buy crappy springs? It's not like it is a major cash outlay for aftermarket springs for flat lifters.

If you have .500 lift cam Just buy .580 - .600 max lift springs in the aproximate range required for your cam lobe type. In the first year most springs loose @10% of their seat pressure. Just a general rule.

So I always recommend another 10 or so pounds on seat new and allow for losses.

Also not running near the max lift makes springs run cooler and last longer. Valve float is very destructive. Is it worth screwing yourself for just another $30 dollars?

You can very the installed height with things like +.050 retainers. It lowers the seat pressure and get more possible lift.
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Old 02-17-2011, 09:23 PM   #5
TheSkunkWorks
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Not sure if you're looking to re-use or buy the LT1 springs in question, but agree if the springs are old I'd replace them anyway. The easiest way for most people to get it right is to just (correctly) install the springs suggested for the new cam.

I also agree it's better to err on the side of a tad more rate and seat pressure than to fall below requirements, whether or not you decide to follow gkull's advice to use springs which allow higher lift. In any event, make sure your retainers and springs are compatible.
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Old 02-19-2011, 02:05 AM   #6
Solid LT1
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Since the LT-1 springs are the same as a 307 2bbl carb SBC max lift is NOT MUCH (about 0.480") Buy some real springs, good ones can be found for as little as $2 each from Melling engine parts. The "off road" Z/28 spring is still less than 0.500" lift (commonly called the #140 spring based on it's part number from the 1960's) that was the spring used in the 67 Trans-Am service package "off road" cam for the Z/28.
Many people think there was a special LT-1/Z28 spring but, the springs in all SBC were the same rates.

Check out Competition Products for decent USA springs in a generic label box.

Link: http://www.competitionproducts.com/C.../products/419/

Last edited by Solid LT1; 02-19-2011 at 02:07 AM.
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Old 02-19-2011, 02:05 AM
 
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