The valve train in the 250 six in my '76 Comet has been making noise for a while now and it seems to be getting a little worse so I thought I'd better get after it and check the adjustment. Imagine my surprise when I pulled the valve cover and found this: Non-adjustable rockers! So now what? How do I adjust these? What other way is there to quiet down valve train noise?
Is oil getting to the arms?? Looks dry... If that's the case you need to find out where the blockage is... That problem settled(if there is one), you'll probably need another rocker arm assembly, as noisy usually means worn out... With assembly removed check for looseness in the arms, if they rock side to side you're holding junk, as only the stands and separator springs will be reuseable... The early 144 & 170 used adjustable rockers but unless there are longer pushrods available that match, you can't just "plop" a set of those in place... Adj arms use a cup on top end of pushrod, while non adj have a ball on either end...
The other problem is, I don't really want to put any time or money in to this engine because it will be coming out over next winter to be replaced by a V8. I'd like to keep this thing running through the summer with as little effort and $$$$ as possible. If an old school temporary "remedy" like dumping in a can or two of STP or something like that will quiet things down and get it through the summer, I'm all for it.
I'd inspect the rockers for wear... If they have no obvious issues the lifters may be failing or cam is excessively worn... Sometimes "miracles in a can" will fix such issues as sticking lifters but nothing fixes worn out parts... The best redneck fix I can think of would be to have bottoms of ALL the stands machined down .020 maybe .025 inch... That should be enough to compensate for wear in valve train... If valves were too tight after machine work you could always put some hardened washers under the assembly... I basically did same on a POS AMC 6cyl years ago, quieted right down...
Try 30 wt. oil if you're not already. Aftermarket longer pushrods can be purchase .10-.60 oversize/undersize.
The slack could come from a combination of wear in the rocker arms, wear in the cam and/or lifter faces, defective lifters, or pushrod ends worn.
