1967 911S Chain Tensioner

[magahey]

Hi- should I put 930 chain tensioners on my 67S or leave them stock if I want to keep it original or does that detract from the car????

[preS]

If you want to keep it original you would have to leave in the 901 tensioners. However from the outside no one can see that the original tensioners are not in, and for that reason I would put the better 930 chain tensioners in.

BTW either tensioner can be used w/ the safe guard.

My $.02

RIchard

[66S]

the 67 tensioners had the cup to catch oil and the tensioner guards might block the cup if they fit at all. I think the original tensioners had no ball check valve but the rebuild kits include a check valve. I rebuilt my 67 tensioners in 1977 with the check valves and they worked fine but Ive used solid tensioners ever since.

[Silverbullit]

Hi- should I put 930 chain tensioners on my 67S or leave them stock if I want to keep it original or does that detract from the car????

IMHO, it does not detract from the "value" ($$$) of the car, unless it was otherwise a truly original (paint, sheet metal, etc.) time capsule. Most of these cars have had some work done on them in the past, and I think the 930 tensioners w/ guards has proven to be reliable and original appearing otherwise. I plan on using this setup in my motor as it goes back together.

[Christophe Penard]

I rebuild my 67S engine. I've put some rebuilt 930 tensionner too (+ guards) and 930 idle arm with DU bushing and new shaft.

[Neil '67 911S]

My rebuilt '67 S also has 930 tensioners but the later SC idler arms but tensioner safeguards were also added. Evidently the original cam chain sprocket idler arms would bind and that was the reason the tensioners failed so often back in the day. No one will know but you.

[VA_alfa]

Can this modification take place in situ or is this procedure major surgery?

[304065]

Can this modification take place in situ or is this procedure major surgery?

It takes an experienced operator about 45 minutes to drop a 911 motor. If it's your first time, maybe three hours. Follow this list and do not hurt yourself, others, your car, the environment, or the feelings of anyone:



Anyway, if you just wanted to do the bare minimum job, you would:

Remove rear engine tin. Note whether you have original KAMAX hardware or modern crap, save original hardware.

Remove M6 nuts holding chain box covers- save original hardware, wave washers, get replacement gaskets

Find a way to apply tension to the chains. Conventionally this is done with a big vise-grip between the idler and the top (bottom) of the chainbox. However, you will not have room to do this with the motor in the car. So you have to find another way, maybe some monster safety wire.

Remove old cup-type tensioners, clean with brake cleaner and place on mantelpiece above fireplace for guests to admire and consider yourself lucky that they did not relax tension and stroke the motor out

Now-- there are two kinds of 930 spring-loaded tensioners-- those with a thick boss for the idler arm stud, and those with a thin one for the later type.

The ones you purchase new are the later thin type. But your engine has the older, unbushed idler arms.

So again, you need to find a way to deal with the old-style idler arms without having the cams jump time. You can either purchase NEW idler arms (big dollars), find used ones (hard to locate and not cheap) or have Henry Schmidt re-bush your ancient ones, looks cool, never tried it.



All right so you deal with the idler arms. While you are in there, check to be sure the studs haven't worked loose from the case- they are an interference fit with a steel shaft into the aluminum chainbox, covered with epoxy on the back so they don't leak. If they are loose, you have to pull off the chainboxes to fix this.

Next: put the tensioner on the shaft, check that it's a good fit with the idler arm, then pull the tensioner pin. You're done, button it back up and don't forget new gaskets.

If it were me, there's no way I would do this mod without checking the cam timing-- if you read the above carefully there are at least three opportunities to lose cam timing-- and it may have slipped anyway.

Also note "while you are in there"

do you have original cam sprockets? these have pointy teeth vs. the blunt teeth of the later type.

How much slack in the chains? When you apply pressure to the idlers to tension the chains, are they bottoming out against the chainbox? If they are, you may want to replace: chains; idler shafts (a 30mm or so steel pin that the idler sprocket rides on), idler sprockets, chain sprockets.

Are there any aluminum chips in the chainbox or ANY evidence of the moving assembly chainsawing against the non-moving bits? This must be immediately fixed.

Anyway, these things are a lot easier if you have the engine out. Good luck!

[Bill Simmeth]

Follow this list and do not hurt yourself, others, your car, the environment, or the feelings of anyone

That last one seems to be the hardest of all these days. Thanks for the chuckle.