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Author Topic:   max valve lift
ChevyRules69
Member
posted September 21, 2004 06:03 PM
I am trying to figure the maximum valve lift you can get with a set of vortec heads and flat top pistons. Any help would be greatly appreciated.

Thanks

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If it has wheels drive it till they fall off


BrianW
Member
posted September 21, 2004 09:10 PM
max lift will probably be limited by head modifications as stock heads can't handle much lift - also vortec's don't flow much past .480-.500 or so, anything more than that is almost wasted valve motion and stress on the components.

piston to valve clearance shouldn't be an issue with flat-tops and any 'realistic' racing cam - but a quick check of clearance with clay before final assembly will guarantee clearances are OK.

ChevyRules69
Member
posted September 22, 2004 12:18 PM
Ok. Rules state no more then .390 int and .410 exa lift on cam. But if i canhge rocker arm ratios and longer push rods and longer valves should still be alright?

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If it has wheels drive it till they fall off


dirtbuster
Member
posted September 22, 2004 12:57 PM
stock vortec with stock valves etc will only take about .450 lift before interference with the top of the vavle guides.


rrrrick
Member
posted September 24, 2004 10:40 AM
[QUOTE]Originally posted by ChevyRules69:
[B]Ok. Rules state no more then .390 int and .410 exa lift on cam. But if i canhge rocker arm ratios and longer push rods and longer valves should still be alright?

Are they measuring lift at the cam or at the Valve?
a cam with .390 lift would be a .585 lift with Stock rockers ( minus the valve lash)
or .624 lift with 1.6 ratio rockers. Those cool Rhodes bleed off lifters will give you more lift when the engine is running, but will measure less without oil pressure ( I wouldn't know how much, I would never resort to such tactics myself