Stock Rocker arms clearances and fit

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scott mattingly

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Guys,
I am running stock rocker arm assemblies and have a persistent lifter "tick" that seems to be getting worse on my mid-70s 360LA in a 74 duster. Engine was "rebuilt" by P.O. and everything looks really clean under the valve covers. Tick is only on Driver side and I have previously pulled/inspected/measured all the lifters and push-rods on that head. They look "nearly new" and the push-rods are all the same length w ~zero wear. So,....not being familiar with these stock rocker arm assemblies, I am entertaining just purchasing a replacement set (probably fm Mancini) and swapping them out since I can find no other "smoking gun" reasons for the "tick."
My QUESTION: Is there any spec on the max amount of cold clearance that should exist btwn the intake & exhaust rocker arms & valve ends on these stamped rockers? OR...Is there any sort of rule of thumb as to how loose the rockers should fit/rotate on the shaft? A few of mine are loose enough be able to grab and rock back and forth a little when they are unloaded. What I mean is that, a few "feel" like there is about .010-.020" of gap between the shaft and the holes through the rocker arms. At the same time, others have a much closer (by feel) tolerance fit on the shaft. (The surface condition of the rocker arms and shaft looks really good with no signs of any previous rust damage etc....)
NOTE: I plan to pull the heads over the winter or next Spring and have them inspected/ "re-worked" or maybe upgrade to Aluminum, so I don't want to invest in a full set of rollers/adjustable rockers at this time. I really just want to get rid of the tick while I drive the car for the next few months.

THX-Scott
 
There should not be any clearance or free play on rockers. When rocker assy bolts are tightened the rockers should preload the hyd lifters. Do you have any shims under rocker shafts. Or you have wrong length on pushrods.
 
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Check the lifters on the side and yes you should only be able to spin the push rods when valves are closed but not be able to move them up and down.
 
Guys,
I am running stock rocker arm assemblies and have a persistent lifter "tick" that seems to be getting worse on my mid-70s 360LA


images?q=tbn%3AANd9GcSQMKH28_zDd3eesve9pv-eI5PORk33DOXWLA&usqp=CAU.jpg

wiped cam ???!!!!
 
I'd figure out which valve or valves are making the noise. Bring the engine up to normal operating temp so it will idle at a low RPM, pull the valve cover, fire it up, and see which valve is making the noise. You can run a .010-.020 feeler gauge between each rocker tip and valve stem to determine that. With the feeler gauge in between the rocker and valve, the noisy one should quiet down. Once you find the offending one, pull the rocker assembly and check it's individual rocker and push rod for wear. If you're lucky it might be one where you can also pull the lifter out with a magnet. If the rocker, push rod, and lifter don't have any wear, maybe the valving in the lifter is bad. Push the center cup of the lifter with a push rod and see if it moves easily. If it does, I'd replace it. If everything looks good, it may be the wrong length push rod. As mentioned, when the lifter is pumped up, there should be no free clearance between the rocker tip and the valve stem with the cam on it's heal for that cylinder.
 
In addition to the suggestions above (all good), I'd ask, do you have an aftermarket cam? Hotter cams have a smaller base circle and the OEM pushrods can end up too short.
 
If you're talking about the stock paddle type rockers, they have all kinda clearance. But if something's ticking and getting worse, something's going on. First, you should verify the rockers and shafts are installed correctly. They have orientations and if they are not installed correctly, they can make noise and worse.
 
You would think that would affect all of them, not just one or two. Anything can happen though.
 
Guys,
I can't believe all this feedback! THX. A few comments:
1) I will check for shims under the shaft. (I had someone helping me when we removed the shafts last year, but I can't recall for sure if shims were in-place.)
2) Car does have a "mild" cam but not sure of exact grind.
3) When cold, there is definitely NO PRE-LOAD on any of the valves/push-rods. Some have more gaps/play than others and I will measure them all cold to get details.
4) Also plan to check operation at idle. (How much oil splashing should I expect at idle? Do I need to rig a shield to keep oil fm running down onto headers?)
5) I do not recall exact push-rod length from when I removed them last year. I simply compared them all to each other and their length was consistent; tips looked nearly new.

--I will provide feedback in the next day or 2 on my progress.
THX
-Scott
 
65 Cuda 340 said:
In addition to the suggestions above (all good), I'd ask, do you have an aftermarket cam? Hotter cams have a smaller base circle and the OEM pushrods can end up too short.
Click to expand...
Reground cams have a smaller base circle. Chevies need a smaller base circle with a higher lift cam in some cases.

Mopar cams are higher in the block so you seldom see small base circle cams.
 
All,
my updates are below...THX much for the assist...
1) No shims were/are present under the rocker shaft
2) Checked for the noisiest rockers while idling(Got very oily/messy real quick...Used a cardboard shield to keep oil off headers)
3) Order 3 replacement LH and 3 replacement RH rockers and installed them.
4) All of the new rockers had much closer fit on the shaft than what was in-place.(expect one of the RHs for some reason was about the same as the older ones.)
5) running valve noise is MUCHO reduced "except" for the one RH "loose" rocker. (Plan to order another couple replacements and install the best/closest fit RH.)
-Scott
 
Just reviving an old thread because I had the same ticking problem. I built my engine over the summer, installed in November. Had a tick from the beginning. Assumed it was an exhaust leak, but didn’t get around to fixing it. Then this happened:

22BF364D-1EF8-4E46-8BB9-6B0A920B2B6C.jpeg
 
If anyone is interested, I have a complete set of the rocker arms only that I'll never use. They are in excellent shaper, & cheap.
 
mopardude318, PM me your email address & I'll send pictures.
 
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