Chain sprocket holder

[Vincent 911]

Hello,

I am upgrading my tensioners with Carrera chain tensionners on my 78 911 SC.

Everything is ready (exhaust removed, oil drain, covers removed, oil hoses removed). To make sure I won't have to re-time camshafts I bought a chain sprocket holder. But I don't know how and where to use it.
Any idea? Upgrading chain tensionners is a common upgrade on our early 911 engines thus I am pretty sure some you guys know where to put this thing (on which sprocket).

Thanks.

[Dennis Kalma]

Uhhh....is your camshaft nut removed as well or are my eyes playing tricks on me?

My first thought is you have the tensioner in already, pull the pin and you'll be set....except for the loose sprocket.

Dennis

[Vincent 911]

Originally Posted by Dennis Kalma

Uhhh....is your camshaft nut removed as well or are my eyes playing tricks on me?

My first thought is you have the tensioner in already, pull the pin and you'll be set....except for the loose sprocket.

Dennis

Sorry, the picture does not correspond to my engine. I took this picture from Pelican tech articles...

So I still have the old chain tensioner and the camshaft nut on my engine.

Any idea where this thing goes?

[Mo_Gearhead]

I believe the tool in question is put in place (of the hyd. tensioner) to keep the chain taut while replacing said parts. If you allow the chain/gear/cam to turn AT ALL during this process, you will need to re-time your cam(s).

And unless you loosen all your valve lash, (allow all valves to close), valve spring tension will TRY and turn the camshaft.

Caution is the byword.

Edit: Sorry, I re-read and may have scared you. I should have said as long as the cam does not move, the chain remains taut and you can insert the new tensioner without the cam/chain/gear relationship changing, you will be ok. You may need an additional set of hands to hold camshaft socket in place while doing this.

[911pcars]

I would not suggest using any human hands or fingers to hold the cam sprocket in place. Avoid personal injury. You can use all manner of wire, wooden blocks and such to limit the travel of the idler gear to maintain tension on the chain so it doesn't skip a tooth.

Sherwood

[KTL]

When I do the right side chain box as pictured above, I use a large socket or some other item placed in the bottom of the chain box alongside the left side of the pressure-fed tensioner. The large socket acts as a spacer/lengthener for the cool little tensioning tool you have pictured (I have one too). You then place the cupped end of the tensioning tool onto the pivot shaft for the timing chain idler arm. The flat end of the tensioning tool goes on the surface of the socket. Orient the flat end of the tensioning tool such that it leans against the socket, pressing the socket into a position that does not allow the socket to move. This is obviously the bottom left corner of the chain box. Then lengthen the tensioning tool to put tension on the idler arm, which pushes the arm up and to the right. Put plenty of tension on the chain to allow you to remove the pressure-fed tensioner.

This arrangement may sound like it is unstable, but it is not. I used this method to time my cams over, and over, and over, and over, as well as to check my piston-to-valve clearance during my top end rebuild. Not once did the contraption come loose. I actually used an aluminum soft socket and that worked well since the flat end of the tensioning tool would slightly bite into the socket. You could accomplish the same thing with a short length of 1 inch diameter wood dowel.

[aigel]

The tool you show is for setting up cam timing. As others say, it goes in place of the tensioner. If you just swap tensioners, a couple of sturdy zip ties in / around the chains will suffice. Remember, all you need to assure is that the chain does not come off the sprockets or jump a tooth. It actually is not that hard to avoid that. To make sure you keep your sanity, you can mark the chain and sprocket with a pen before you begin.

George

[Walt Fricke]

Vincent

This is designed so that the rounded end of the tool fits onto the round shaft that holds the idler sprocket. This is the shaft you install with the cutout upward, so it can catch falling oil and oil the idler gear. It has a roll pin sticking out of it.

The flat end of the tool, on this side, goes just above the lower of the two 13mm nuts you can see in the picture, which hold the chain housing to the case, and the 6mm stud boss just above it. Its end is flat and skinny so it can fit there, horizontally.

You then turn it to make it extend until you have plenty of pressure forcing the idler to the right, and therefore upward, keeping the chain taught. This pressure keeps the tool in place also.

At that point you can just pull the old tensioner off, plop the new one on, pull its pin, and you are in business. You don't really need to futz around with tie wraps or wires or whatnot - your chain is not going to skip a tooth.

Glad you included a picture - where to put this for me is a kind of "I know it when I see it" deal.

Walt Fricke

[Vincent 911]

Is that the correct position?

[Walt Fricke]

Close

Turn the flat end 90 degrees, and slide it in just above the nut, but below the casting protruberance which holds the 6mm stud, so it presses against the housing close to its sealing lip.

Ah - but you knew that, you just couldn't manipulate the images in that fine a detail. Well, I couldn't have superimposed anything, so you are ahead of me in that department.

Walt

[Mo_Gearhead]

I believe it is.

[Vincent 911]

Thanks all. I have changed my chain tensionners without any issue.

I did use this specific yesterday evening. It worked pretty good. it was a little bit tricky on the right side but very easy on the left side.

I did nnot use any piece of wood a steel wire or whatever strange stuff.

Thank you and see you soon on the road.

[hcoles]

I found the keeping tension part all easy... getting the new tensioners bled and compressed and then slid in without slipping and letting go... not that easy... also I made and installed Jerry Woods "slugs" to limit travel in case of tensioner failure