How to adjust adjustable rockers?

-
b5cuda

b5cuda

Well-Known Member
Joined
Jun 30, 2007
Messages
224
Reaction score
33
Hi, I'm getting a little more clatter at idle on my adjustable lifters and wondered how to adjust them? I have the 273-type factory rockers on a 340 X-head engine. Running a hydraulic cam. Appreciate any tips - thanks!
 
Another try at the chart, you have to know what you are setting the lash at .028 ?
Valve adjustment chart NON PDF.jpg
 
Thanks for posting. I've only done this on a slant six before so before so appreciate all advice.
 
got a pic of your set up?i'm going to use the 273 rockers on my new engine.
 
b5cuda said:
Hi, I'm getting a little more clatter at idle on my adjustable lifters and wondered how to adjust them? I have the 273-type factory rockers on a 340 X-head engine. Running a hydraulic cam. Appreciate any tips - thanks!
Click to expand...
hydraulic cam use the chart and set to zero lash plus 3/4 turn
 
If you feel comfortable that the initial setting is correct you could just give them all a 1/4 turn.
 
May try that first, since it has been running pretty good.
I don't have any good pic's of the setup, will take some and report back once I get the chance to adjust. Thanks!
 
a while back Engine Masters did extensive tests on preload with hydraulic lifters...as much as .070 before issues developed.
what is a good setting...045? I bet standard stamped rockers are all over the place.
 
OP, is this just 1 lifter tapping?

Step 1: Try the 1/4 or even 1/2 added turn. (But I'd skip to step 2 just to be sure things are set correctly.)

Step 2: If the clatter does not subside, then you'll need to go through the process of backing off, then snugging up each rocker, and then add the 3/4 to 1 full turn on the adjuster. Use the chart in post 2 to determine which rockers to adjust at what crank angle.

If you are not familiar with valve and crank positions in that chart: Each line of that chart is with the crank rotated 90 degrees CW from the prior setting. Line 1 is with the timing marks at 0 and the valves on cylinder #6 are 'at overlap'... i.e., both valves on #6 will be slightly open about equally. If not, then rotate the engine a full turn 'til the 0 marks line up again and the #6 valves will be at overlap and you can start the process.

Step 3: If that does not do it, then you'll have to investigate the possibililty of a lifter(s) getting weak/collapsing and needing to be replaced. That problem seems to be getting more common these days.
 
Seems to be coming from passenger side, and it may be just one. Planning to get to it after work either late today or Monday. Will let you know - thanks for the reply!
 
b5cuda said:
Seems to be coming from passenger side, and it may be just one. Planning to get to it after work either late today or Monday. Will let you know - thanks for the reply!
Click to expand...
It may have got skipped initially, mis adjusted, or you have a adjuster that backed itself off. Original 273 rockers just had a interference fit between the rocker threads and the adjuster with no lock nut like the Crane and other aftermarket rockers had. If your loose adjuster doesn't have much resistance when you turn it you may need to try a new adjuster or remover the rocker from the shaft for replacement or repair.
 
b5cuda said:
Seems to be coming from passenger side, and it may be just one. Planning to get to it after work either late today or Monday. Will let you know - thanks for the reply!
Click to expand...
That would make me think of a particular lifter having issues, or an adjuster getting loose, or some other wear issue. The loose adjuster ought to be obvious. A weak lifter sometime can be found by first running the engine for about 5 minutes to get the oil warm and the lifters pumped/filled up. Then stop engine, remove valve covers, and press down on the pushrod end of each rocker; any soft lifter found at that time is a possible suspect. These are just some suggestions of what to look for and methods.
 
ir3333 said:
a while back Engine Masters did extensive tests on preload with hydraulic lifters...as much as .070 before issues developed.
what is a good setting...045? I bet standard stamped rockers are all over the place.
Click to expand...

I go for light preload. I'v run as little as .010" preload and IMO they run better that way.
 
I'm tight on time this weekend but got a few minutes to pop the passenger side valve cover and tighten down each rocker 1/4 turn. First impression, it seems to have helped. Will have to drive some more next week and see how it does. If it starts acting up more I'll do the full-on treatment. Thanks guys!

adjustable rockers.JPG
 
Has the surface been machined flat where the lock nut sit or is it a rough casting ?
 
Not really sure - I didn't take the lock nuts off, just loosened enough to tighten the screws 1/4 turn. I didn't find any loose ones and they locked down pretty tight.
 
Yeah you need to make sure the nuts don't come off! The factory arms are not set up for plain nuts and they will come loose sooner or later. And if they come off...... IDK what will happen but it might not be a good thing..............
I run my anti pump-up hydraulics at .020 preload, and don't readjust until it's worth my time to go in there; it seems to run best when it clatters a bit lol.
I'm just lazy that way. It's been clattering since about 2005, lol.......
 
b5cuda said:
I'm tight on time this weekend but got a few minutes to pop the passenger side valve cover and tighten down each rocker 1/4 turn. First impression, it seems to have helped. Will have to drive some more next week and see how it does. If it starts acting up more I'll do the full-on treatment. Thanks guys!
Click to expand...
If 'twer me, when time allowed, I'd still go back and look for soft lifters. It's possible that you
  • have a soft/collapsing lifter and tightening the adjuster just pushed the piston in that lifter further down in the lifter body, and it is changing the sound a bit when the pistons bangs into the bottom of the lifter body (which it should not be doing). You can tighten that up more and more 'til you take up all the piston travel and it will be quiet.... but you'll essentially have a solid lifter with no valve lash.... which will hang a valve open a hair and eventually burn it.
  • you had one or more excessively loose adjustments and you tightened it up, but not enough
Find the time to do it right, don't just guess it is OK. Doing the next step in the process will put the adjusters where they SHOULD be, and you will be able to really know if things are good or there is another problem. Right now, you don't really know where things are set relative to where they should be.
 
b5cuda said:
I'm tight on time this weekend but got a few minutes to pop the passenger side valve cover and tighten down each rocker 1/4 turn. First impression, it seems to have helped. Will have to drive some more next week and see how it does. If it starts acting up more I'll do the full-on treatment. Thanks guys!

View attachment 1715380494
Click to expand...
Looks like you have Crane style lifters with the lock nuts. That's a good thing. Good luck.
 
Hi again, finally going over the rockers to ensure proper adjustment this weekend. I pulled the driver's side shaft and noticed it has no banana groove and one set of holes (eight total) for oiling. Is this shaft OK to run?

rocker shaft.JPG
 
You must log in or register to reply here.
-

Back
Top