01-31-2021, 12:33 AM
...and watching + filming yachts around Auckland waters.
If I was committed to a shim change because I was out of range and I had a choice of the looser end rather than tighter I think I would go the looser. The theory that the clearance always closes up doesn't ring true for many either.
Based on my trade experience with variety of valve jobs that includes adjustments, I would also choose a thinner shim to have a greater clearance/lash.
The rule of a thumb is: as the valve's face or seat wears, its clearance reduces as well.
Too loose valve is a better and safer option than too tight, which if neglected, will burnt out, resulting in lower compression and misfire that produces HC = unburnt fuel, if ignored, will be plugging up vehicle's cat, not to mention about pollution.
(01-30-2021, 05:33 AM)Tev62_imp Wrote:(01-30-2021, 05:18 AM)bflint_imp Wrote: Getting ready to re-shim my valves after 52K miles. Recommended shim sizes (per calc) either put new clearance on low side or high side of spec (IN 0.006, EX 0.011). I noticed, via calcs, that I could deviate from the recommended shim size to push new clearance from low side to high side or vice versa, while still staying within spec range of +/- 0.001. WHY? Because I noticed that the measured clearances historically show the EXHAUST getting tighter (or staying the same) and the INTAKE getting looser.
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The recommended shim size for EXHAUST is fine, but I have two choices for INTAKE. For INTAKE I have choice of 0.065 (recommended) or 0.051 new clearance. I was thinking I should pick 0.051 with the assumption that they will loosen over time.
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General mech theory states that looser is safer. Am i crazy to go to the tight side? Thoughts?
If I was committed to a shim change because I was out of range and I had a choice of the looser end rather than tighter I think I would go the looser. The theory that the clearance always closes up doesn't ring true for many either.
If I was committed to a shim change because I was out of range and I had a choice of the looser end rather than tighter I think I would go the looser. The theory that the clearance always closes up doesn't ring true for many either.
Based on my trade experience with variety of valve jobs that includes adjustments, I would also choose a thinner shim to have a greater clearance/lash.
The rule of a thumb is: as the valve's face or seat wears, its clearance reduces as well.
Too loose valve is a better and safer option than too tight, which if neglected, will burnt out, resulting in lower compression and misfire that produces HC = unburnt fuel, if ignored, will be plugging up vehicle's cat, not to mention about pollution.