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Discussion Starter #1
Question.

If a spring is rated for say .550 inch lift, what would a safe cam lift be for that spring. I am assuming I shouldn't go for a cam lift right at the spring rating. Or any spring rate, is there a percentage I should leave as a safety factor?

I don't want to totally waste the spring lift either. Obviously I could go WAY under, but would like to go as close as possible without having to worry about it breaking.

Avoiding breakage would be really good. :)

Thanks,
Russ
 

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As a builder you should be looking for a spring bind spec of .050 to .080". You should pull a few springs and check the install height to verify what you have anyway as well.
 

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Discussion Starter #3
Uh, thanks, but what are you telling me?
Sorry, no clue.
Russ
 

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What he is saying is , if you have a cam with NET lift ( not gross , before lash) of .550 , you look for a spring that "coil binds" ( goes solid) at .600-.630 compression from the installed height. For example if a spring coil binds at 1.200 you would want an installed height of 1.800-1.830 so that you have .050-.080 more than the net cam lift. Having more spring "travel" is mot necessary and can have a negative affect . Then you have to select a spring that has pressures compatible with your cam at those specific heights. Add to that the fact that there will be "some" pressure variation in a set of 16 that can only be found with a spring pressure tester. Preparing a set of heads for a performance application can take hours.
Randy
 

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Discussion Starter #6
Thanks.
Not a true performance build, but sounds like something I can do.
Main reason for the question is I am looking at different cheaper aluminum heads that come with the springs installed. Most have 0.550 springs installed.
So quick take I am getting is in this case I would be wanting to stay below 0.500 on the cam just to be safe without needing to worry?
Putting better springs in is always an option.
Not going anywhere radical, don't want to get into piston to valve clearance issues.

If this engine is even usable. That's a different can of worms.

Thanks
Russ
 

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If a spring is rated for say .550 inch lift, what would a safe cam lift be for that spring.

I would assume that if a company says their springs are rated for .550" lift then that's exactly what they mean- you can safely use a camshaft and rocker arm that provides up to .550" lift. In other words the safety factor before reaching coil bind is included in their number.
 
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