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Old 04-29-2013, 03:45 PM   #1
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Default Shim under Bucket setup

Hey all,

Just wondering, how does one go about setting lash on a SUB setup? A friend of mine posed that question to me and I really didn't know how to answer.
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Old 04-29-2013, 04:13 PM   #2
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  • Install your lifters without the shims.
  • Reinstall camshafts and torque down to spec.
  • Take a lash measurement with cam lobe pointing straight up from lifter. Take careful notes, and do not mix up the lifters to cam lobes. It is best to leave it together until you have your shims.
  • Subtract the amount of lash needed from your measurement.
  • Order the correct sized lash caps from the measurements taken. There will be different sizes.
  • Remove camshafts.
  • Install the proper lash caps that you have determined from measurement on all lifters.
  • Reinstall camshafts and torque to spec.
  • Double check all measurements.
  • It is possible to grind down the lash caps with sandpaper on a very flat surface if your measurements comes up too tight.
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Old 04-29-2013, 04:38 PM   #3
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re: the last bullet-
I never did mine with cams torqued. I did one valve assembly at a time with the cam laid in position. Just got the shim close but over and wet ground to fit by sticking it on the end of a valve and using a standard machinist's wet stone grinder. This process was per the engine builder and I never had a problem.
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Old 04-29-2013, 04:52 PM   #4
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This is excellent information, thanks guys. Is there any suggested range to keep it within?
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Old 04-29-2013, 06:22 PM   #5
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Quote:
Originally Posted by m2cupcar View Post
re: the last bullet-
I never did mine with cams torqued. I did one valve assembly at a time with the cam laid in position. Just got the shim close but over and wet ground to fit by sticking it on the end of a valve and using a standard machinist's wet stone grinder. This process was per the engine builder and I never had a problem.
Am I to assume you did not have your valve springs in place during this process?

I had my cylinder head assembled. The other cylinder's valve springs would have lifted the camshaft off the head if I did not have the caps torqued down.
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Old 04-29-2013, 06:33 PM   #6
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Quote:
Originally Posted by Der_Idiot View Post
This is excellent information, thanks guys. Is there any suggested range to keep it within?
If stock cam, go to the tightest side of the factory valve lash spec on the 99 or later head. The exhaust side is a tad looser than the intake side.

I actually went a tad tighter than factory spec to get a little more lift and duration. It has been a while since I had a stock cam with my SUBs, so I do not recall exactly what it was. I had gotten this advice from the folks at Mazda Motorsports. You need to be real confident that the measurements are right.

If aftermarket cam, go by what is stated on the cam spec sheet.
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Old 04-30-2013, 09:42 AM   #7
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Quote:
Originally Posted by miata2fast View Post
Am I to assume you did not have your valve springs in place during this process?
Yes- springs are in, bucket/shims are not, except for the bucket/shim assembly being checked.

1. Remove all the shims/buckets
2. Install shim/bucket assembly
3. Check/set lash
4. Remove and install next assembly
5. Rinse and repeat

Removing all the other shims/bucket assemblies allow you to roll the cam into the position you need it to check that valve assembly without interference from the others.
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Old 04-30-2013, 10:14 AM   #8
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Of coarse, it all makes sense now.

I guess either way will work. I think on a bench your method might be better, but if doing the operation with the motor in the car, my method would at least keep you from bending over so many times.
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