So I finished up with replacing the valve springs and rebuilding rocker arm ***emblies on the Y block, all new rockers and rocker shafts, pushrods &c. Lash is set .019" Have read all screws should be about the same height. What is the issue when they are not. Can't be anything good - cam lobe/lifter getting lunched?
Looks like the adjusting screw has been screwed down quite a ways and then backed off. Maybe accidentally screwed down really tight, wiping a lobe off? Also might check to see of the rocker arm has worn into the rocker shaft or maybe a pushrod is bending?
It's a new rocker, never been installed. They are all new rockers. New rocker shafts, etc. I backed 'em all off a bit before installing the rocker ***emblies. The screw might have looked like that when I got it. Maybe somebody dinked with it in the last 50 years, but the ball and rocker are definitely NOS. Pushrods, rocker shafts, rockers all new hardware. Everything. I've since ran it up for about 20 minutes to break in the new valve springs and drove it about a half hour cruising and it runs better than ever. Wouldn't a bad lobe or lifter cause it to run real bad? Runs real smooth now. Pulls steady high vacuum, etc.
Here's what the plugs looked like, removed them to replace valve springs. The low screw is #6 exhaust if I'm thinking right.
A bad cam lobe would cause it to run bad. If it gets bad enough it will spit back through the carb when you get on it. I would put a dial indicator on it at the valve itself, roll it through by hand, and compare it to a couple of others. That will show you if the cam lobe is worn. What you might be seeing is just the manufacturing tolerance stack of that combination of parts. I remember reading where Smokey built a checking fixture and went through a pile of rocker arms to find 16 best ones. Good luck
The rockers were purchased in three lots, a mish mash of NOS on that auction site. They are getting kind of spendy otherwise, my avg. price ended up at $7 per, which I thought was pretty good. These are all 1.43 ratio rockers, regardless of markings. 5751066 is OEM markings, service replacements didn't have markings. The 1.54 ratio rockers are shorter on one side and marked different, ECG 6564. Any valve work itself would have been done long ago. The springs needed shimming, but the valve stem tips were even with a steel rule placed across? Checking valve lift against the others sounds like a good plan.
Not trying to be a wise *** but the rockers can't all be in the same position at the same time, unless there's something very wrong! Admittedly however there does seem to be more adjustment 'used' on one of them. I'd be rechecking the lash first and then measuring the lift. Pics from a better angle might help too - hard to see if the pushrod to the one in question is raised or not. Chris
True, might be all 1.43 but the threaded boss on the 575 looks thicker than the others( no step at threaded boss? )
See, that's why you guys get paid the big bucks, for pointing stuff like that out. 7 of the rockers were different in finish and might have been OEM, three looked to have some sort of coating. Some looked almost as if they'd been honed and rocker tips resurfaced. So I put all of one kind on the intakes and the others on exhaust, or that was the plan anyway. Y blocks are weird in that it's EIIEEIIE iirc.
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