spring question

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Feb 3, 2007 | 04:30 PM
  #1  
does anyone know what the maxumum lift the stock valve springs can take?
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Feb 3, 2007 | 07:50 PM
  #2  
This may help:

Vin 8 and 7, Valve Spring Dimensions
Free Length 1st step 2.03 in
Damper Spring 1.86 in
Installed Height Intake 1.7187 in
Exhaust 1.5937 in
Seated Pressuure 76-84 lbf at 1.7 in
Compression Pressure 194-206 lbf at 1.25 in

I'de say they are good for .470"-.480" lift.
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Feb 3, 2007 | 08:48 PM
  #3  
In most cases they'll actually take about .500" becuase they use a rather small diameter wire (ususally more than the stock head itself will take before retainer-to-guide interference happens). Unfortunately, that also means they don't have enough tension to control a performance cam that would lift them anywhere near that high.
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Feb 4, 2007 | 11:35 AM
  #4  
thanks for all the help, i thought it was somewhere around .480-.5. that will be more than enough for my new cam. its the TPIS flat tappet cam.

@.05 lift 221/230 and .454/.454 lift. it should be a good match for my stock headed motor. that along with my new runners and ported base should make this thing haul aZZ. iam hoping for mid to high 13s, i think she should get there.
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Feb 4, 2007 | 11:55 AM
  #5  
Quote: In most cases they'll actually take about .500" becuase they use a rather small diameter wire (ususally more than the stock head itself will take before retainer-to-guide interference happens). Unfortunately, that also means they don't have enough tension to control a performance cam that would lift them anywhere near that high.

have you ever heard of anyone haveing problems wiyh a cam that big with the stock springs? by the way their from a 85 L98 there still preaty new so i dont need to replace them if i dont have to. i was also looking at a crane Z cam it has 218/230 and .459/486 lift (both cams have 112lsa) both will give very similar resualts, but i think that the lift on the Z cam maybe too much.
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Feb 4, 2007 | 11:57 AM
  #6  
most i have head ppl running on stock heads is .480 and i think some one has stated they are using the Lt4 hotcam on stock heads/springs with the 1.5 rockers...which is .492 lift.

i wouldnt recommend that
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Feb 4, 2007 | 12:20 PM
  #7  
Quote: most i have head ppl running on stock heads is .480 and i think some one has stated they are using the Lt4 hotcam on stock heads/springs with the 1.5 rockers...which is .492 lift.

i wouldnt recommend that
what about the Z cam i talked about in the post above. iam thinking that i should just go with the TPIS cam and keep it safe.
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Feb 4, 2007 | 05:29 PM
  #8  
They'll physically take the lift, but valve float can occur at frighteningly low RPMs. Stock springs were barely adequate for the stock cam up to 5000 RPMs.

A set of Comp 981 springs are true drop-in replacements for stock and will control a mild performance cam MUCH better than stock springs will. A set of cheap "Z-28" springs off the internet will work, too, for less money.
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Feb 4, 2007 | 10:00 PM
  #9  
sweet, thanks for the help. i might get those springs.
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Feb 4, 2007 | 10:43 PM
  #10  
Don't forget the valve seals. Check them for clearance.
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