Most folks agree that swivel foot adjusters are a worthwhile upgrade, particularly when compared to the poor quality of new aftermarket adjusters that tend to wear or mushroom at the tip over time. The swivel foot also reduces side loading on the valve stem and lessens valve guide wear significantly.
There are two types of swivel foot adjusters: Pinto style and Porsche style. The Porsche style are also called 'Elephant Foot' adjusters. The reason why is obvious in the photo below. Pintos on the left and Porsches on the right.
Pinto swivel foot adjusters are much less expensive than the Porsche style, plus they have that nifty oiling hole in the shaft, so you may be tempted to use them. Don't. That little swiveling ball is known to occasionally dislodge from its socket and, as you can imagine, may cause major problems.
Unfortunately, changing to swivel foot adjusters is not a direct swap in for the stock style. The adjuster thread is only 8mm, so it must be used with rocker arms that are 8mm (from the 72-74 bus engine, I think). Additionally, the swivel foot requires significantly more space between the rocker arm and the valve stem. To get this space you need to do two things:
First, you have to grind off a little bit of the rocker arm. This photo shows the stock rocker arm on the left and the ground rocker arm on the right. Although it is hard to tell, only the surface facing the valve stem is ground down enough to be level with the shoulder of the arm. Sorry the photo is a little blurry.
The other thing you need to do to gain more clearance is elevate the rocker shaft. This can be done with an appropriate sized washer under the rocker shaft stands. I can't tell you how thick the washer should be. You will decide how thick it should be as you reset your rocker arm geometry.
The appropriate sized washer will lead to perfect alignment (a straight line) from the valve stem through the adjuster screw when the valve is at half lift. The following photo shows the swivel foot adjusters in place (ignore the rusty nut - it was temporary). The adjuster furthest away shows proper geometry with good alignment of the adjuster and valve stem at half lift position.
Valve adjustment is a little more difficult after you make the change since there are two fairly large flat surfaces on each side of the feeler blade, but you get used to it. In fact. I think valve adjustment becomes more precise because of the larger surface areas.
Tim
