Supertech cam followers/valve lash

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revolutionz_s13
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Supertech cam followers/valve lash

Post by revolutionz_s13 »

So I have supertech cam followers, which are a shim under bucket design. When I got the buckets, there were no shims in them. So now I'm trying to set the valve lash. I have Jim Wolf cams, spec for cold valve lash is .010-.012"(.25-.30mm) My problem is, I cant get to within those specs with the supertech shims, the smallest they make is 1.45mm. For example, my #1 intake valve measures right now 1.677mm. Using a 1.45mm shim, I would be .227mm off. I have BC stock size valves installed, with BC springs/retainers. Does this sound right? the only way I can think to correct this is I have to take the entire head apart and have the valves ground down....hopefully someone can chime in on if this is what needs to be done, or am I measuing something wrong, or even would i be alright running slightly tighter clearances? Im learning here, just need some input...first motor I have built :D
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KoukiKAT
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Post by KoukiKAT »

Get a decent honing stone and fluid and hone down the shims if they're too tall.
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revolutionz_s13
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Post by revolutionz_s13 »

I think what Im going to do is run a tighter clearance, like a .20mm. Being the motor has yet to run, I think some stuff will settle down a bit after the first couple heat cycles. I just need to get it to something close so I can get the motor put together so its ready to go in and run. Once I do the heat cycles, I'll re-measure the valve lash and see where I sit, get the valves to within spec, and then i'll degree the cams.
92 240sx SE KA-T project
95 240sx SR20DET Daily
92 integra - winter beater
KoukiKAT
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Post by KoukiKAT »

Do a compression and leak down test as well if you decide to run those tighter tolerances, just to be sure valves aren't being cracked open when the motor is up to temp.
The 240SX is dead. Long live the 240SX!
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smracing
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Post by smracing »

It will just get tighter after running a while
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Kfred
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Post by Kfred »

If your tolerance is too tight your risk burning an exhaust valve. Also, as smracing said, the lash gets tighter with wear.

Do it right and take your head/cams/"lifters" to a competent machine shop and tell them what clearances you want to run. They will hit the top of the valves and everything will be great.
RIP Nate(480sx)...
revolutionz_s13
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Post by revolutionz_s13 »

so what shims should I order? just the smallest ones supertech has, put those in, and then bring the whole head to the machine shop? Or just take the valves out and bring the valves themselves to the machine shop? Im just trying to have to assemble and disassemble the head as few times as possible. I wish I would have known the valves needed to be ground down prior to putting everything together....noob engine building ftw hahaha
92 240sx SE KA-T project
95 240sx SR20DET Daily
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Kfred
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Post by Kfred »

Measure all the clearances with no shims. Then use this formula to figure out which shims you need:

Current clearance - desired clearance = shim size.

Get shims that are as close to the calculated shim sizes as you can. If the shim size falls between two, get the bigger shim.

Then put all the shims (in there correct location based on your calculations/measurements) in the head and put the cams in. Measure all the clearances and make sure no clearances are too big. Then bring the head to the machine shop and they will do the rest.
RIP Nate(480sx)...
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