I have a 1981 Targa that was built in 1980. When I took my timing chain covers off I found that I had the early style cams that need the 46mm crows foot. Wayne from Pelican wrote of finding these in an 82 911 so I suppose others have had the same issue.

What have others done about the required tools to remove the nut? It seems that a crows foot is neccessary but a 1-13/16" (46.0375mm) tool should work and be cheaper. Snap-on has it for ~$50 and McMaster-Carr.com has one for $30. The cam itself requires a 17mm width tool but I do not see why a 17mm open ended wrench or a 17mm open ended crowsfoot with a breaker bar would not do the trick.

The latest issue of Panorama has an interesting read on the Carrera Pressure fed tensioners in the tech section. The writer does not speak praise of the standard practice of replacing the mechanical tensioners. He says the tensioners do not just fail catastophically and they can easilly be monitored for trouble. I see good reason in buying the upgrade for $600 instead of $400 to replace with the original bits but I may consider just reusing my stock tensioners especially since they already have the safety collars on them.

 

Why are you loosening the cam sprokets anyway ? do oyu have some type of oil leak that you are trying to fix ? just wondering because I have an oil leak that will require this also. I have a 78 so I definitely need the tools so am also inyterested in responses.
I have the updated tensioners and although either could fail , I would not risk my engine on hoping i could hear an old tensioner failing.

PS are you going to retime your cams with the engine still in the car ?

 

The tool to hold the cam is P 202. Because cam nut torque is fairly high I find it helpful to put a 3' long piece of pipe over the P 202 to help hold the cam in position during timing/torquing (once you have the timing correct and the nut snugged down you don't want the cam to move during tightening). Replacing cam o-rings and re-timing the cams can all be done with the engine in the car, but I would recommend removal if you're going to replace the cams.

I highly recommend tensioner replacement using Carrera oil-fed units - they're the only way to go. Also, at the same time, be sure to replace the (6) chain guides.

Keep in mind that when you buy a crowsfoot, if it's not the factory tool, it will probably be too weak for the job. To fix it so that it can't "spread" open you will probably have to weld a support of some kind across its open end...

 

I have my engine out to replace the head studs which 6 or 7 of are broken and one cylinder leaks under load.

Here is the snap-on tool: http://buy1.snapon.com/catalog/item....re&dir=catalog I wouldn't worry too much about it not being able to handle it but I do see that the Porsche tool is reinforced. The Snap-on tool also mentions 1200 in.lb. working torque but I don't know which part of the tool that is measured at.

Can all the chain guides be replaced without splitting the case? The chain would have to be replaced though.

 

The cam nut crowsfoot looks like I remember it, and you will have to reinforce it with a piece of steel welded over the open end. 1200 lb/in = 100 lb/ft, and the torque spec for the cam nut is 108 lb/ft. In addition, you have no way to know how much force will be needed to get the nuts loose.

Replacing the chain guides is straight forward, and is very easy when the chain boxes are removed. You can do the guides with the engine in the car, but you have to remove the engine mount center pylon in order to get the pins out of the two inboard guides on the right side.

Before you loosen the cams check how much of the tensioner is showing where it engages the idler arm - if the chains are not stretched they should be OK. If they are stretched you can buy chains with a master link, and install them with the lower end assembled.

If you need a machine shop recommendation for your head work let me know...

 

Since you asked, I have used the P202 for removal and retiming, but I also experimented removing the nut with a 46mm impact wrench and this worked nicely, but only for removal. The reason I tried this is because at the time my P202 broke. (It was defective and Pelican replaced it.) I was desperate to keep my momentum going at the time, so a trip to the local specialty tool store and I had a huge 46mm impact socket ready to go. Maybe Pete will tell me this wasn't such a good idea...

 

Actually, that's fine - it even saves wear & tear on the shoulders and arms! I think that the stress from the "impact" of the impact wrench is probably considerably less than what goes on inside the engine...

 

I do believe I have found some engine tools that I will be able to borrow. That leaves me with money to spend on the transmission tools I will have to buy.

I would not worry about the 108 ft*lb being to far outside of the 100 ft*lb "working" torque. Where is 108 ft*lb measured at? The factory crowsfoot acts as a torque multiplier does it not? So is that torque at the nut or torque at the tool?

I see how the chain rails come out now. Very simple! I was thinking they would go in like the outer rails and the case would have to be disassembled.

"Before you loosen the cams check how much of the tensioner is showing where it engages the idler arm - if the chains are not stretched they should be OK."
What do you mean by this? If the chain is stretched then the tensioners will not show tension on them?

 

take a pic and post it .. as the chains stretch the tensioner will plunger will become elongated as it takes up more and more slack. Someone of Petes experience will probably to look at the pic and tell you if your chains need replacing.

 

I did not have a camera to take a photo of the timing chain before I removed it. It would supprise me if Pete could actually make that diagnosis with a photo. Especially since he has not spoken up about what you said yet. How much does the chain actually stretch? How often do they need replacing as oppose to are they changed as simply part of a rebuild?

I borrowed the tools for the job and was able to get the nut off by myself. I am disappointed with the quality of the Porsche tool. The metal seems a little too soft and the tool was deforming on some of the working surface. It was also difficult to keep the tool properly positioned on the nut. The crowsfoot can be slid on or placed on the nut so that it grabs an extra corner. I found that putting the tool on so that it holds an extra corner was more stable. I also though that the crowsfoot should have been tighter fitting but it is possible that this is a result of the working surfaces being deformed and increasing the free movement. The tool slid off on me one time and rounded the point of one of the corners on a nut. The tool came off because of the difficulty of holding the tool on correctly. The cause for the difficulty was from the free movement of the tool on the nut and this allowed the crows foot to rock forward when force was applied decreasing the tools hold on the nut. It may be possible that this tool was a rare occurence of not beng manufactured up to standard but considering that one rennlisted already stated that his was replaced because it was defective, I would presume that there is a low level of quality. I would not expect such a problem from a Snap-on tool and if I were to buy one, I would purchase the snap-on crows foot and try it. The benefits of the snap-on tool are also that it is a flare nut type and will wrap further around the nut and hold it better and be thus less likely to slip off. It also has a life time warranty but may require a ~1 inch extension to clear the chain housing with the breaker bar. It is also cheaper.

Pete, you mentioned needing to weld the crows feet closed. What type of experience with this can you share? What brand was it?

I used the other special socket and I thought that a 17 mm crowsfoot may work better since it would stick out less far. It would certainly be worth a try.

 

A chain diagnosis for "stretch" would have been very easy to do with a straight-on photo. For example, if you refer to the picture on page 87 of my book, the 8th edition, you can see the distance between the top of the left side idler arm and the chain housing, directly above the tensioner. That distance is the important dimension, I've disassembled 911 engines where the idler was almost touching the housing - those chains had to be replaced!

Please find a crowsfoot with homemade support pictured. This can be done with any quality socket - you don't want to modify it and then have the square drive break off!

FYI: My P 202 pictured is a factory tool, and I've been using it for 30+ years... You might want to try Baum Tools, or even the P-car dealer, for one that's better quality. Note the wall thickness of the socket end, I couldn't even guess at how many cams that tool held in place!