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YOUR RESEARCHRebuild: Timing chain too tight
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Install single row pro imsb
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Performed · outcome unconfirmed · Original poster
I�m not sure that it matters, but I also installed a single row pro IMSB from LN before trying to time�engine also rotated smoothly after that.
Leading evidence: 'Install single row pro imsb' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'easier way' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Install single row pro imsb' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suspected cause · Original poster
THIS is probably the easier way to have done this�thanks so much
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Tighten large bolt and the four exhaust cam shaft bolts
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Suggestion
Tighten large bolt and the four exhaust cam shaft bolts on just enough so that the chain does not fall off, and both pulleys can still rotate and not move the cams.
Tighten large bolt and the four exhaust cam shaft bolts
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Suggestion
Tighten large bolt and the four exhaust cam shaft bolts on just enough so that the chain does not fall off, and both pulleys can still rotate and not move the cams.
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I could really use some advice. After having a bore scored 3.6 engine (C4S, three chain) machined, I�m following Jake Raby�s rebuild video series to put everything back together. I�ve gotten to timing bank 1, but after fitting the intake cam (with sprocket) and exhaust cam, I have no slack whatsoever to slide in the exhaust cam sprocket. The chain will not give me any room, and the cams are sitting nicely on the lifters and journals.
I�ve never had this issue on timing. I�ve checked that the timing chains aren�t bunched up, the engine rotated incredibly smoothly before this point, and the ends of the cams and cam lobes are all lined up perfectly.
I�m not sure that it matters, but I also installed a single row pro IMSB from LN before trying to time�engine also rotated smoothly after that.
Any ideas on what I�m missing? I�ve watched this portion of Jake�s DVD over and over.
thanks in advance
C4S (model in the OP), which (you know what) all have the same 3-chain m96.03 for 996. But 2003 MY, in case this helps you.
I�ll get pictures�really looking forward to your input.
Did you MATCH the length of each new chain with the preexisting chains that were removed?
Jake Raby has mentioned this many times over the years. He's said, when ordered the chains from Porsche, it's not uncommon to get chains of the wrong length. You must trust BUT verify.
I did, yes, laid out all chains and they were exact same length. I�ve been following the video religiously so very confused at this point. Also, I removed the cams and put a bore scope through the timing wells to make sure the timing chains are both seated on the IMS.
3-chain model.
OK, Install the cam shafts, lock them down so they stay down, and lock the ends so they don't rotate accidentally.
1. Loosen the big center bolt for the intake manifold sprocket so it can rotate freely on the the cam shaft. You need a tool to do this, buy it from ebay. You also need to BUY a new bolt. (I did this with the cam OFF the engine and using an Impact driver)
2. Leave the exhaust sprocket OFF the exhaust cam shaft.
3. Pin the crankshaft pulley so it does not move.
4. Leave the tensioner OFF
5. Loop the chain over the intake sprocket, fit the big bolt on to the intake cam shaft loosely
6. Pull the chain tight (between the intake pulley and below), fit the exhaust cam pulley on the chain, take up the slack again and fit it on to the exhaust cam shaft. Use only one or two M6 bolts to loosely keep it in place
7. Tighten large bolt and the four exhaust cam shaft bolts on just enough so that the chain does not fall off, and both pulleys can still rotate and not move the cams.
8. Install the chain tensioner. Tighten it to spec. This will keep the chain tight.
9. Tighten the intake sprocket large bolt to spec.
10. Tighten the four M6 bolts to spec. Apply blue loctite if you are reusing the bolts.
Get on the 997 forum, search for "my borescoring adventures" and somewhere in there is how to do this with some pictures.
Thank you all for the helpful comments. Figured it out. In case this helps someone in the future, here�s what I did:
place the exhaust sprocket in first (not on exhaust cam), then tilt in the intake cam and sprocket. Roll the intake cam backwards to take up the slack in the timing well (you have to plan this out, so you get close to correct positioning), then slide in your exhaust cam and mate it up to the exhaust sprocket. Essentially, this makes sure you aren�t losing helpful chain length in the timing well BEFORE your stuck with the chain engaged on the teeth of any sprocket.
again, thanks for the quick replies
