Cam Chain Tensioner

[MikeSimon]

I put my original cam chain tensioner back together, and when I compare it to the replacement one I bought, I find the force required to compress it is much higher in my original tensioner than for that replacement one. Were there different spring rates? I did not measure the spring length and probably should do that and compare. Which one would you use?

[Shvegel]

I would use the one that came with the car as it has worked for the life of the car.   I don't know the exact history of our tensioners but I assume there are many variants with single and double chains and even perhaps V8 versions (?).   Sometimes when fashioning a replacement in order to cover the entire range things like springs will be uprated to cover the entire range.  NEW means Never Ever Worked. 

[Pawel66]

Not to refer to what Shvegel wrote, although it supports it, but just as a caution, although you probably know this already: it is not this spring, really, that provides tension to the chain. That is why it is so important to prime the tensioner and pump it initially by hand (or rather by a large screwdriver) before you finish the assembly.

The spring, I think, is more like a return spring to keep sprocket on/in the chain, allowing the pumping action of sprocket+lever to take place all the time the chain is moving. That is at least how I understand it.

Just read about it a lot when did my timing last winter (shaft, chain, sprocket, rockers, tappets), fellow Members explained it to me and I followed the advise.

[Tyler S]

Yes, the spring is there to supply preload to the tensioner pin, arm, and sprocket when the car is not running. The piston bore of the tensioner is only a machined surface and has no seals. Without the spring, the tensioner would bleed down its oil over time.

[MikeSimon]

I understand that the hydraulic pressure is key to the proper function. I was just curious how much of a role the spring load plays to overall performance. It is a substantial difference in force required to compress the tensioner.

[MikeSimon]

This all depends on which publication of the BBB you are referencing. Since the M127-129 existed before 1968, a majority of the info on the 6 cylinder motors is in the August 1959- edition.

I was able to obtain a copy of the 1959- passenger car manual. Still, no particular info in there either about removing and installing the inline-6 cylinder head. I know, in principle it is the same procedure as for the L-4, but is there any info anywhere specifically about the 127 to 130 engine heads?

[Tyler S]

Everything you should need is in the manual. Unfortunately they are not set up like Haynes or Chiltons manuals. The easiset way is to put post it notes bookmarks in the various sections related to the removal. Such as “job 05-1 removal of rocker arms”. Or “job 05-15 removal of twin roller chain”. Then you can easily flip to the sections during removal.