Jump to content
HybridZ

Shaved & Shimmed P79 - use 300zx springs? No Spring shim needed?


turbogrill

Recommended Posts

Hi,

 

The 300zx outer vavle springs are about 0.1" taller than the L28 valve springs. Could I use them in 0.080" shimmed P79 and not have to deal with with adding shims for the springs?

 

The will be installed at slightly different installed height but this is good since it would add some extra pressure for a mild afermarket cam?

 

Thanks

Link to comment
Share on other sites

I believe what is meant is the idea of shave the head, shim the towers and use n47 valves. the valves are between .080 and .100 longer (depending who you ask) and thus people say to shim the springs that same amount to keep the pressure and installed height the same. I'm also curious about this, could one get away without shimming the springs by using stiffer valve springs they were going to use anyway? This will give pressures slightly below advertised specs, but I don't think it'll make a huge difference. Theoretically this could also give another .080-.100 of clearance for additional lift (unless the inner spring binds first)

Link to comment
Share on other sites

I believe what is meant is the idea of shave the head, shim the towers and use n47 valves. the valves are between .080 and .100 longer (depending who you ask) and thus people say to shim the springs that same amount to keep the pressure and installed height the same. I'm also curious about this, could one get away without shimming the springs by using stiffer valve springs they were going to use anyway? This will give pressures slightly below advertised specs, but I don't think it'll make a huge difference. Theoretically this could also give another .080-.100 of clearance for additional lift (unless the inner spring binds first)

 

Yes and getting slightly lower seat pressure might not be too bad, specially if you have a cam with a ramp that is not too agressive.

 

Goot point with the coil bind, it should buy you some margin.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...