Mecanical vs Hydraulic tensioner

[Xavier PJB]

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

Thank you will remember this guideline.
All the best

[tom1394racing]

Thank you will remember this guideline.
All the best

Xavier

Your kit includes the spacer to set the distance from the collar to the tensioner housing.

[911int]

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.

I think people do often forget why the hydraulic tensioner is developed. A normal spring tensioner has at any temperature nearly the same force of tensioning. A hydraulic tensioner lefts tensioningforce while becoming hotter, caused by a loss of viscosity of the hydraulic fluid.

So, the most tensioning force is necessary when the engine is cold and all the mechanical parts are not enlarged by heat. After becoming warm the mechanical elements enlarge and the distances from one element to the other “grows”.
If you have in that situation the same force tensioning the chain ( mechanical tensioner ) this force will be delegated to the different elements of the camshaftdrive, with the result of more wearing of the bushings, bearings, gearwheels and the chain itself.

So the hydraulic tensioner is developed and used to prevent wearing

Competition engines have their own rules. Wearing is no argument because these engines are constructed for highest performance and normally overhauled in little periods.

The backup system with the security collars is smart.

An interesting technical solution offers the Alfa Romeo V6 engine of the GTV6 which has a hydraulic tensioner intergrated in the normal oil circle. A theoretical top solution but with the problem of oil leakage – in that car the oil is leaking on the timing belt. Therefore it was replaced by an mechanical bi-metal tensioner.

Hope it helps a little

Best regards

[JT912]

These are the cup style which I found when I cracked open this engine a few days ago. Looks like the original owner went the route of retrofitting to a mechanical tensioning setup. There have been some interesting surprises on this car.

[NorthernThrux]

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.

Good eye. This was after a 150 mile drive, so full operating temperature. Maybe 15 minutes after parking at most. So I'd expect some sag, based on oil viscosity as was mentioned.