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Anthony
Join Date: Jul 2019
Location: Anchorage, AK
Posts: 63
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Last Minute Checks... Concern?
Rebuilding '81 911sc for first time. Installing 964 cams in the new rebuild. I just finished timing the cams and re-installed the chain tensioners.
Feeling pretty good, but preparing to seal up the chain housings led me to do one final check on the cam timing and sprocket alignment, which then led to a couple questions/concerns... 1) The left side camshaft is at 1.27mm at TDC (recommendation is 1.26mm), the right side is at ~1.24mm at TDC. I figured that's close enough - or is it necessary to get them closer together? 2) I got the sprocket alignment set to left side being ~0.25mm off, and the right side is ~0.05mm off. (Couldn't get the left side any closer, because I'm using 0.5mm shims.) Anyways, re-checked with all the rockers, idler arms, chain tensioners, etc installed... Right side still looks good... but now the left side appears to be off by ~0.40mm... Re-checked several times and get around that same number. Should I be concerned about this? Does it warrant taking everything out and starting over with the shims to get within +/- 0.25mm? Any advice is appreciated, Thanks! -Anthony |
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04-15-2020, 04:26 PM
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Anthony
Join Date: Jul 2019
Location: Anchorage, AK
Posts: 63
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In the very, very short time since I posted this, I decided to work my way back to the cam shaft shims and start over the sprocket alignment... It's really more the sprocket alignment that had me worried... I kinda rushed through that stage the first go around, only measuring a couple times before moving on.
Feel I should spend a bit more time on it, do the due diligence, and have better peace of mind in the end. Plus, it just makes for more practice! |
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04-15-2020, 06:56 PM
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Registered
Join Date: May 2003
Posts: 3,346
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Good idea. Misalignment results in rapid wear on the sprockets.
-Andy
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72 Carrera RS replica, Spec 911 racer |
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04-15-2020, 07:49 PM
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