318 Magnum rocker ratio?

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1968fish

1968fish

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I know all the LA motors from the factory were 1.5, I can't remember but I thought that I read at one time the Magnums were 1.6? Building a magnum and starting to look at cam choices.
Thanks
 
Magnums are 1.6 ratio. The stock heads won't allow much more lift. So be careful!

My dad has a .320 lift comp cam I believe and was rebuilding a 5.9 and thought he would use that cam for some extra grunt. That .320 lobe lift ends up being .512 with the 1.6 ratio and it was a no-go. I think he said the springs started binding up on it. Can't remember now. A spring swap might work?
 
70aarcuda said:
Hughes Engines

springs retainer and locks...bolt on no machining....620 lift
Click to expand...


I have those same springs on my Hughes EQ 2.02 heads. They're supposedly only good for .540 or so lift. What's the deal with that? I'm running a Hughes .539 (ironic) lift cam to try and stay under "the limit".
 
that is what the ad says....

  • Installed Height/Pressure: 1.660"--120#
  • Pressure @ .450" lift: 280#
  • Pressure @ .500" lift: 300#
  • Pressure @ .550" lift: 310# <-see note below
  • Coil Bind: .620" lift
  • Outer Spring ID/OD: 1.033"/1.440"
  • Type of Spring:Single w/ damper

    Our camshafts are not comparable to other manufactures and require special valve spring pressures to operate and live satisfactorily. ONLY USE springs meeting the specifications listed here or on the provided cam cards. Valve spring pressures and installed heights are supplied with each camshaft.



    Note: For cams with .540"+ lift, we recommend our double spring - Part number HUG 1129

 
watch for keepers hitting stem seals
watch for retainers hitting bottom of rocker esp with smaller base circle, increased height keepers/ retainers and you have not done the mid lift drill (yet)
stock rockers will take the lift if set up right
 
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