I am about to reinstall the timing chain on my V-12 and have all the dampers in the proper positions and a new tensioner. The ROM takes about jackshaft positioning, but prior threads seem to confirm that jackshaft position is unimportant with the distributor out. I will appreciate a little help on the following:
Can you confirm that I don’t need to worry about holding the jackshaft in position when installing the chain or, alternatively, tell me how to do it?
Are there any special tricks to installing the chain and getting proper chain tension around the whole length of the chain, or does the tensioner deal with everything?
1/ the sole purpose of maintaining the jackshaft position is to make sure the distributor rotor points to the same place as before and thus maintain unchanged ignition timing when working on cylinder heads in isolation;
2/ chain tension and/or camshaft position is not something you have to worry about if you break the chain at the A bank and attach the new chain there (usually using a masterlink from old chain to new). You then advance the crank, which directly pulls the Bbank, which rotates the jackshaft sprocket, which directly pulls the Abank. Thus the whole chain goes on and rolls itself round at full tension and the excess (old chain) is removed and extracted at the top of the Abank once the masterlink is again visible and accessible. You then use the masterlink to complete the new chain. Then the tensioner can be restored and hence continue to maintain the relationship between the sprockets going forwards.
You mustn’t rotate the engine backwards during the process because there is no tensioner to “deal with everything”.
Since there are no heads on it either, all you can do is feed chain into the gap under the crank sprocket and turn the crank.
You can only determine how much chain wear there is by comparing it against a new one directly or by fitting it and looking at how far across the tensioner sits. Search for the pics I posted some time ago on another chain tensioner thread.
Sorry to try your patience, but “feeding the chain in” assumes a broken chain with a master link. The OEM chain and the replacement I am buying are both continuous, with no master link. Since I can pull out the sprockets easily to fit the chain, can’t I just install it in one piece? I assume this takes some effort to fit it right - Is there a step by step process for that that anyone can share? Or do you recommend putting a master link into the chain even if it comes in one piece?
Thanks for your patience and help. I am finding this topic kind of confusing.
You are starting with a much more disassembled engine than any of the manuals anticipate, so you can more or less just invent the procedure as you like.
Take out the crank sprocket, loop the chain onto it and put the crank sprocket back onto the front of the crank. There isn’t space under the crank sprocket to do it any other way than by feeding an end in and rotating and usually no one has disassembled the engine so completely beforehand. Most people have the starting point of a complete engine and so do this by taking just the minimum number of parts off of the engine - i.e. just the Abank cam cover and nothing more.