Chain tensioner update on a 71 2.2

[Gearbox]

Have been toying around the idea of up grading my 1971 911S for quite some time now to the carrera hydralic tensioners, and I think it's time to start accumulating the parts. Does anyone definitively know what other parts I need besides the kit? I've heard about the kit not being complete for a 71 so I'm looking for a list of parts and part numbers. Thanks Allan

[RTincher]

Allan, lots of good threads on this both here and Pelican, with split opinions on whether to do the pressure-feds or the 930's with guards. There does seem to be consensus on using the updated idler arms, which are not cheap at $375-400 the pair. I don't think they are usually included with the kits.

Good luck.

[Gearbox]

Yeah, been reading all the threads about the great tensioner debates and decided to go full boat with the pressure feds, ramps, idler arms, and the John Wood fix. Just wanted to know if anyone had all the part numbers I needed for the extra parts. I also understand that I would be missing some oil plumbing parts, etc. Figure someone had done this before and still had all the correct part numbers. Thanks Allan

[Jeff Higgins]

I used the kit available from Zim's. It was the most complete, and had everything necessary; all the plumbing, everything. The only thing not included is the double pivot bushing idler arm, so if you keep your old ones, you need to use the spacers provided behind the tensioners. No one includes the newer idler arms; that's considered a seperate issue (although it really shouldn't be).

There was a thread on the Jerry Woods fix on Pelican. It's pretty easy to do. The hardest part is finding the correct diameter brass tubing for the internal safety stop; it's a rather odd size (I can't rmember exactly what size right now). Anyway, I found the right size at a hobby shop that sells radio control airplane and model train equipment. A company called K&S makes all kinds of brass tubing that these folks use.

Just a couple of things I would like to add to the Pelican thread. Cutting the tube to the short length needed can be difficult. It's so short that normal tubing cutters have too much distance between the support rollers to hold it. I cut it long with a fine hobby exacto hacksaw and squared it up later. The other thing is to check clearnance on both sides, both tensioners. Left and right are probably different due to tolerance build-up in manufacturing and assembly. If you only go through the measurement process on one side of the motor, the other side will likely have too much or too little clearance. I don't think "too much" would be as big a deal as "too little", but you might as well check both sides anyway. Oh, and make sure you prime the tensioners before putting them in. I think they are full of air as delivered.

[t6dpilot]

Gearbox, I know you have made up your mind, but I am going to give you my $.01 FWIW. I recently went the tensioner update route in my 71T and am happy with the result. But... After I did that, I talked to two guys who are VERY knowledgeable and experienced with early 911's. Both of them have built and maintained numerous long hood vintage race and street cars for many years. The comments were, "yeah, I used to put the pressure fed tensioners in early cars, but I would not do that now. I know much more about the cars that I did when I first started building and maintaining them. I would install the mechanical tensioners with the collar guard and be done with it. If you are not racing the car, then it is probably not going to be an issue going that route. Besides, I do not believe that the early cars really have enough oil pressure to justify the use of the tensioner update."

Or some words to that effect. I trust these guys implicitly and they know these cars better than the back of their hands. I cannot backup their justifications, but it makes sense. If I had it to do over, I would probably go the mechanical tensioner route. Anyway, my $.01...

[Vic Elford]

I'm just curious, as I'm not very mechanically inclined, as to what an update should cost. My car is currently having the update performed (1971 911t coupe w/ original Zeniths and 115k original miles), my engine is very strong, and very dry, and I'm being quoted $1,500 (at a local Porsche specialist). Is this a fair price, or should I be looking elsewhere? Thanks everyone.

[911scfanatic]

Vic Elford should know the answer to that question.

[Paul Schooley]

I've been running mechanical tensioners in my street 2.7 car for years with no issues whatsoever. I'm sure there's a ton of arguements on this subject though. In the end I've saved a fortune and time using them with no ill effects.

[Jeff Higgins]

I have run all three possible set-ups at one time or another. Original hydraulic, straight mechanical, and pressure fed. They all work, and with the later double bushing idler arms, any one of them are pretty darn bullet-proof. Believe it or not, cost is about the same by the time you buy a pressure fed conversion kit, or buy the later 930 style narrow boss hydraulics that allow for the double bushing style idler arms. Please note, the most common failure mode on the pressure fed set-up has been addressed with the addition of the stand-offs to support the external lines. So, if you prime them, install the internal stops, and use the stand-offs, there isn't much that can go wrong. Anyway, I don't want to re-hash the great tensioner debate. You asked what you need; the simple answer is the Zim's kit. You won't have to buy anything else at all.

[Gearbox]

Thanks all, and Jeff, found the Zim kit. Very inexpensive compared to everyone else which makes the idler arm upgrade an under $1000 effort. Great news. So just to be absolutely clear, the Zim kit has the "stand offs" you mentioned, the idlers are a "have to have", and I need to perform the Jerry Wood mod, yes? Also, with this set up or the 930 Turbo upgrade, it is a highly recommended mod over the stock tensioners, even with the collars? I don't mind investing the $1000 but if $22 would cover it, what should I be doing here? Thanks Allan