Using timing chains with master links on a 964
09-07-2018, 09:09 AM
#1
Rennlist Member
Thread Starter
Using timing chains with master links on a 964
In the past year, I have read of two 964 owners finding timing chain circlips on their magnetic sump plugs.
The latest case brought a response from a Porsche trained mechanic that I thought was worth repeating. The 964 and 993 were not designed to fit timing chains with master links as the chain ramps on those models interfere with the circlips, dislodging them. I did a search on Pelican and noted that only continuous chains featured in the 964 search.
If you must fit a chain with a master link (because you don’t want to split he case), then you have to modify the chain ramps to allow room for the circlip to pass. If this saves one engine it’s worth it.
The latest case brought a response from a Porsche trained mechanic that I thought was worth repeating. The 964 and 993 were not designed to fit timing chains with master links as the chain ramps on those models interfere with the circlips, dislodging them. I did a search on Pelican and noted that only continuous chains featured in the 964 search.
If you must fit a chain with a master link (because you don’t want to split he case), then you have to modify the chain ramps to allow room for the circlip to pass. If this saves one engine it’s worth it.
09-07-2018, 01:20 PM
#2
Burning Brakes
Jack.pe mentioned finding a link in one of his video's. The information you state is correct, my Indy said exactly the same when I asked the question but it would seem not all engine builders are aware of the issue. I'm not even sure the guides can be modified tbh.
09-07-2018, 05:03 PM
#3
Rennlist Member
Thread Starter
This excerpt is from a 2007 Pelican forum post
I replaced my continuous with master links while engine was disassembled. However, be very careful about the chain ramps. In my 964 the ramps/rails, whatever you call them, have raised ridges on the outer edges, presumably to help "guide" the chain along the ramp and control lateral slop. These raised ridges will pop the little E clip right off the master link post. I had to dremel (actually a razor blade works best as they are just plastic) the ridges off my brand new set of ramps to prevent this from happening when the motor is running. I'm pretty sure a timing chain coming loose would grenade the motor. Moral of the story - don't try this with 3.6 motors "in situ". Now that I've "butchered" my ramps, however, I could do it in situ - though I don't think I'll ever really need to replace the chains without removing the motor. If it's a pre 3.6 motor I don't think the ramps have these ridges on the outsides but worth a check - I know the chain itself will wear a groove into the ramps. Just be sure to check the clearance between the E clip and any part of the ramp it might touch. Oh and the ramps tend to get quite brittle over time.”
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I replaced my continuous with master links while engine was disassembled. However, be very careful about the chain ramps. In my 964 the ramps/rails, whatever you call them, have raised ridges on the outer edges, presumably to help "guide" the chain along the ramp and control lateral slop. These raised ridges will pop the little E clip right off the master link post. I had to dremel (actually a razor blade works best as they are just plastic) the ridges off my brand new set of ramps to prevent this from happening when the motor is running. I'm pretty sure a timing chain coming loose would grenade the motor. Moral of the story - don't try this with 3.6 motors "in situ". Now that I've "butchered" my ramps, however, I could do it in situ - though I don't think I'll ever really need to replace the chains without removing the motor. If it's a pre 3.6 motor I don't think the ramps have these ridges on the outsides but worth a check - I know the chain itself will wear a groove into the ramps. Just be sure to check the clearance between the E clip and any part of the ramp it might touch. Oh and the ramps tend to get quite brittle over time.”
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09-07-2018, 05:10 PM
#4
Rennlist Member
Thread Starter
The purpose of my post is not to start an oil type thread. It’s just as someone who has rebuilt his own engine, I know how deep in the process the chain installation is. It would be a major disappointment to me as an Amateur DIY to learn that this possibility existed after months and $$$ rebuilding my engine and the Information wasn’t widely known. At least now, builders can research more. As shown by the two public incidents, it happens.
09-08-2018, 03:51 AM
#5
Burning Brakes
I know my Indy would not use a split link chain, do it properly or not at all. As you say there is a lot of work involved in getting the chains to run parallel and making sure the guides are installed centrally. Given that fact I would not be comfortable altering the guides. Good info for anyone thinking of a rebuild for sure.
09-08-2018, 08:49 AM
#6
Rennlist Member
If the case is split why would you use a chain with a master link? The chains without master link are only $33-50 each. I am currently rebuilding a 993 engine and although the chains are in excellent condition for $66 I didn't think twice about replacing them with new.
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09-08-2018, 09:23 AM
#8
Rennlist Member
I agree Anthony. Here is the thread http://forums.pelicanparts.com/911-e...ster-link.html
Some people???
09-08-2018, 01:48 PM
#9
RL Technical Advisor
FWIW,.....we never,. ever use a master link chain.
If an engine needs new ones, there are a whole host of other components that need replacement as well and its not that much additional effort to split the case to the job properly.
If an engine needs new ones, there are a whole host of other components that need replacement as well and its not that much additional effort to split the case to the job properly.
