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80% leakage - where is it going? - should be obvious. Should be able to hear it. If it is out the exhaust then ex valves would be suspicious.
80% leakage on all cylinders tested?
Skipped a tooth? You can check this with the engine in place. A visual check would be close enough for this purpose - you are looking for 1.5+mm deflection on the I valve at TDC #1 and the corresponding same on Z4. You can guesstimate that much by observation. Saves the hassle of rigging a dial gauge in there (but it is do-able).
If you have bent valves, the clearances should be well off.
Edit . Are you sure you are doing the leakdown right? Z1 (#1 firing, not #1 timing). If you are on the timing #1 you will get something like 80% leakage - both ends-valve overlap.
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Last edited by Alan L; 05-09-2024 at 05:04 PM..
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