cam chain tensioner

[Iowa Mark]

I have two different engines ( a '75 and a '79) and, it would seem, two different cam chain tensioners. One of these engines came without the acorn cover nut. Up until today I didn't think too much about it. I decided to adjust the chain tension and had already stolen the acorn nut and lock nut from the other engine to use when I was done. The first engine doesn't have enough threads exposed to allow for a lock nut when adjusted. When I pull the rod out of the second engine to compare, I find that it is longer than the first adjuster rod.
In the tech section I see there was a set that looks to not require a lock nut, but everywhere I look in the manuals on adjustment, it is reminding me to lock the jamb nut to keep the adjustment in place.
Is there any differences in the parts between the two different sets, besides the rod? Am I missing something not shown in the pictures? Also, on a related matter with the adjustment, Is it normal to have the rod pulse as I rotate the engine over. I thought this would be a smooth constant preasure against the cam chain?

 

[jd750ace]

There's several iterations of the adjuster, look in the tech section. The oscillation of the rod is normal. The valve springs will variably back-load the chain, unless the chain is too tight.

 

[gggGary]

5twins has a great comparison of all the various adjusters through the years (somewhere...) and I like retiredgentleman's the adjust while idling
I don't look at mine with the engine off and cold. I only check mine after the engine is hot and the engine is idling. With it hot and idling I adjust for about 1 to 2 mm of rod in/out motion. If the camchain rattles too much, then I tighten up adjustment slightly.

Yes some motion of the rod is normal AND essential to the life or your chain and guides.