I like the real bulletproof feeling with solid chain tensioners, no hydraulic tensioner can be called bulletproof, reliable yes IMHO. Sometimes you have to wait for the chains to stretch on a newly rebuilt motor before the collars can be installed. Your 68 motor can use pressure fed tensioners. New hydraulic tensioners are not inexpensive these days, solids are.
Last edited by 66S; 05-10-2021 at 01:49 PM.
Solid tensioners have their own issues. Great for a race engine where you inspect frequently and can adjust to take up the slack each time. Not so great for a motor which you might not tear down for 100,000 miles.
Early 911S Registry # 2395
1973 Porsche 911S in ivory white 5sp MT
2015 Porsche Macan S in agate grey 7sp PDK
You don’t have to tear down an engine to adjust chain tensioners, as easy as valve lash adjustment, just remove the rear shroud and chain covers, no big deal. I’ve used them in most engines I have built and like them, somebody has to stand up for them because they are demonized. The only bad thing about them is they may stretch a chain more than hydraulics which have a dampening effect. If I noticed unusually fast chain stretch I wouldn’t use them. Fail proof as you can get.
Last edited by 66S; 05-11-2021 at 03:21 AM.
I guess it depends on how often one wants to pull those covers. Not at all hard like you say, but just one more thing to do. Modern cars spoil us for maintenance. That being said, I have no idea how often one should be checking the hydraulic ones for failure (I know you can hear it) or chain stretch.
TBH, I'm not sure why someone didn't make a purely mechanical spring loaded one, which would be elegant, bulletproof and not require frequent inspection. Something like a valve spring has the right diameter and compression force to be easily adaptable. But I've never seen anything like that for the air cooled cars.
Early 911S Registry # 2395
1973 Porsche 911S in ivory white 5sp MT
2015 Porsche Macan S in agate grey 7sp PDK
There was such a tensioner, made by Hoeptner. Sadly he stopped when the pressure fed came out.
Early S Registry member #90
R Gruppe member #138
Fort Worth Tx.
You have an encyclopaedic knowledge Ed. After you mentioned that, I remembered reading something about this on Rennlist I think.
I've often wondered whether you ever cast eyes or worked on my car, which was purchased new at Forest Lane in the summer of '73. It lived in the Dallas area till 1988, so who knows?
Ravi
Early 911S Registry # 2395
1973 Porsche 911S in ivory white 5sp MT
2015 Porsche Macan S in agate grey 7sp PDK
I drop the engine once a year - hence checking and cleaning everything - so that works for me
Safety collars ordered from Tom.
Chain tensioners are the same debate as tires or engine oils I guess. Thanks to everyone on that wonderful forum for he contribution. I wish I were in the USA to meet few of the cool cats here.
O-G 26 - Early911S 2407
Xavier, as you can see your tensioners were already upgraded to the 930 type, and you did not have the original 68 versions.
Also your chain ramps have been upgraded, and from one large bronze bushing I see it's likely the idler arms have been too.
The safety collars should have 3.5 mm of clearance from the tensioner housing, and if that's not possible then it's recommended not to install them.
Ravi's safety collar looks quite close to the tensioner housing, for a presumably cold engine. For reference, the hex in the collar's screw heads is roughly 3 mm.
Jon B.
Vista, CA