Late '60s BB hydraulic valves adjust rocker nut down (full turn, 1/2 or 1/4 ?)

[Ronald L.]

Re: Late '60s BB hydraulic valves adjust rocker nut down (full turn, 1/2 or 1/4 ?)

Chuck same book, Started at 6-16 dog-eared as the important point and through 6-25 with that was disappointed that there was not more, now I see that in the next section.

The other method outlined by Duke & others above gets to the same point. If you see the intake go down, up and then the exhaust starts, the intake is full up, you can do this cylinder by cylinder. Then hot with the cover off, you can do the same thing, as described, loosen until there is noise and then tighten.

#5 intake done cold twice and cranked to 1 turn still clatters. To me the rocker has a wiggle that the others don't have. The rocker itself appears the same as the others, the tip is polished but no wear at all on any of them.

[Chuck S.]

Re: Late '60s BB hydraulic valves adjust rocker nut down (full turn, 1/2 or 1/4 ?)

...#5 intake done cold twice and cranked to 1 turn still clatters.

Now, you know the clatter is not resulting from improper adjustment.

If you do the hot adjustment, you should notice a change in the noise as you back out the one turn preload adjustment on the #5 intake lifter. As I said before, I would expect the noise to change to a hollow knock different from the existing "clatter" or "ticking". I wouldn't leave it there long; the lifter is telling you there's freeplay in the valve train.

[Ronald L.]

Re: Late '60s BB hydraulic valves adjust rocker nut down (full turn, 1/2 or 1/4 ?)

I did that - hot back out and then re tighten, no change in tick.

So what I mean is that while the lifter is tight to the push rod, it can rock slightly on the stud. If you grab it - it can wobble a very little bit. Others not at all perhaps #5 intake a very slight amount.

[Timothy B.]

Re: Late '60s BB hydraulic valves adjust rocker nut down (full turn, 1/2 or 1/4 ?)

If the engine has press in rocker studs is there any chance the stud is coming up.

[Joe C.]

Re: Late '60s BB hydraulic valves adjust rocker nut down (full turn, 1/2 or 1/4 ?)

If the engine has press in rocker studs is there any chance the stud is coming up.

Timothy,

I think that all Mark IV engines originally came with screw in studs and pushrod guides.

[Chuck S.]

Re: Late '60s BB hydraulic valves adjust rocker nut down (full turn, 1/2 or 1/4 ?)

I did that - hot back out and then re tighten, no change in tick...

During the hot adjustment, did ANY of your valves get noiser as you backed out the preload? (The point of the question is make sure you have actually experienced the sound of a hydraulic lifter with free play in the valve train.)

Typically, noise increases as you just begin to get free play in the valve train. HOWEVER... if you don't back the preload out completely, there won't be any change in noise because nothing changed re valve train clearance.

If you haven't observed any change in noise on ANY of the valves, as you backed out the preload, I believe I would confirm I was actually removing all the preload by backing out (ONLY) the one turn on the #5 intake, then shutting the engine off and trying to move the push rod with my fingers. If you still have preload on the lifter, you will not be able to move the push rod up/down between the lifter and rocker arm. Rocker movement does not count.

My experience with hydraulic lifter adjustment is on a 327 small block. The noise of freeplay in the valve train MIGHT sound quite different on a big block, but I would be surprised.

But, I have to tell ya, it's causing me a little pucker advising you on hot adjustment of your big block valves without you knowing what a hydraulic lifter sounds like when there's freeplay. I should have emphasized what the manual says...make all adjustment changes 1/4 turn at a time, and allow the engine to re-stabilize between adjustments.

My opinion is your problem is not adjustment; I would look elsewhere, and barring better big block advice, I would suspect the rocker has too much wear. Polish does not indicate lack of wear; it simply means the wear has occurred at a VERY slow rate with lubrication.

[Ronald L.]

Re: Late '60s BB hydraulic valves adjust rocker nut down (full turn, 1/2 or 1/4 ?)

Chuck, My experiece with worn rocker comes from low or poor case hardening, something done in-house in the 70's and due to the age of the furnaces, from the beginning of time. I will try and get a different rocker and see what happens. Does any one know if the 427 rockers all had a "M" stamped in the inner side?

[Ronald L.]

Re: Late '60s BB hydraulic valves adjust rocker nut down (full turn, 1/2 or 1/4 ?)

427 rocker arms - what is stamped inside the originals, M? L? or?

I have seen M and L but I don't know if they are original. I expect the L is the SHP long slot rocker. That slot looks to be 3/4" and the slot on the M rocker 5/8".

What were the 66 427/390's originally built with? M, L, or???

Back to this noise thing, it is a clicking, and I attribute the noise to the ability to rock these rockers side to side - very slightly.

The noisy rocker #3 intake I replaced with a used, clean L-slot rocker, turned after push rod is tight, to 1 full turn.

At the same time I noticed that the other suspects on that same bank, #5 and #7 which I could get to rock slightly - but less that #3 intake, also had that same rock. A quarter turn on all those make them stiff.

I did this with the motor parts very warm, after 15 minutes of warm up where I started to notice #3 intake tick. It was not doing it cold. The rockers do not show any abnormal wear, in fact seem rather new, and like I said in an earlier post, I have seen worn off center rockers with slots all worn out. None of these show that.
All the guide plates and studs are firmly screwed in place; push rods clean and perfectly straight. Studs do not show any shank wear indicative when you have a rocker sliding around cutting into it...

Could this be slight lifter collapse that just keeps getting worse?

Oil pressure on stock pump is 40 or higher.

Or rocker arm nuts backing off?

The last time I did this I am sure I started at 1/2 and then ended up tightening the rocking ones to 1 turn, now I am at 1 1/4 turns.

How far can you crank them down before you create a problem?

[Chuck S.]

Re: Late '60s BB hydraulic valves adjust rocker nut down (full turn, 1/2 or 1/4 ?)

427 rocker arms - what is stamped inside the originals, M? L? or?

I have seen M and L but I don't know if they are original. I expect the L is the SHP long slot rocker. That slot looks to be 3/4" and the slot on the M rocker 5/8".

What were the 66 427/390's originally built with? M, L, or???...?

I have no detailed mechanical knowledge of big block engines. The letters "M" or "L" are probably a stamp identifying the supplier. IN MY OPINION, that stamp does not specifically identify a rocker design. There is unlikely to be any correlation of specific supplier with specification, such as "slot length"...UNLESS...the specification just happened to be a running change that was made WHEN a given supplier began manufacturing the rocker arms.

...The last time I did this I am sure I started at 1/2 and then ended up tightening the rocking ones to 1 turn, now I am at 1 1/4 turns.

How far can you crank them down before you create a problem?

I was afraid this might happen when you said there was no change in the sound as you made the adjustment.

Ron, you should NEVER make ANY valve adjustments without knowing your starting point with certainty. I recommend you do not drive the car or run the engine until you have adjusted all the valves cold following the service manual procedure.

I tried to scan the service manual procedure for you without success...our TDB software requires the user jump through hoops, resizing documents and reducing file size, until it is happy and satisfied. Such is beyond my technical capability.

[Ronald L.]

Re: Late '60s BB hydraulic valves adjust rocker nut down (full turn, 1/2 or 1/4 ?)

Chuck,
I have the CSM, and found the details on the page you mentioned. I did do that, and adjusted all to 1/2 turn beyond the loose point.

The issue is at that point the rockers are tight, do not have any possible rock.

When I run it for more than a half hour, gets really hot, then we pick up on this tick. on going up and down in revolutions.

At that point I added 1/2 turn, and then yesterday, another 1/4 turn.

After the run, the rockers, some, not all can be grabbed and have a slight rock. Note - this is subtle and in all cases no wear is detectable on the studs.


On the L, I recall from buying them in the late 70's that the L stood for Long slot rocker. Chevrolet special perf parts had these and they might not have been a RPO. All mine have an M FWIW and the slotted ball studs are barely worn, they just look broke in on the contact surfaces.

Lifters or springs or rockers...

[Chuck S.]

Re: Late '60s BB hydraulic valves adjust rocker nut down (full turn, 1/2 or 1/4 ?)

Chuck,
I have the CSM, and found the details on the page you mentioned. I did do that, and adjusted all to 1/2 turn beyond the loose point...

When I run it for more than a half hour, gets really hot, then we pick up on this tick. on going up and down in revolutions.

At that point I added 1/2 turn, and then yesterday, another 1/4 turn...

I disagree that you have adjusted your valves as the CSM describes.

Hydraulic valves are adjusted in two crankshaft positions...At TDC, Number 1 firing position (Adjust exhaust valves on 1, 3, 4, 8; Intake valves on 1, 2, 5, 7), and in TDC Number 6 firing position (Adjust exhaust valves 2, 5, 6, 7; Intake valves 3, 4, 6, 8). Number 6 firing position is ONE crankshaft revolution from Number 1 firing position.

From the CSM: "Valve adjustment is made by backing off the adjusting nut (rocker arm stud nut) until there is play in the push rod. This may be determined by rotating push rod with fingers as the nut is tightened (fig. 4V). When push rod does not readily move in relation to the rocker arm, the clearance has been eliminated. The adjusting nut should then be tightened AN ADDITIONAL 1 TURN to place the hydraulic lifter plunger in the center of its travel. No other adjustment is required."

...The issue is at that point the rockers are tight, do not have any possible rock...

As expected on those valves being adjusted at that firing position...if the rockers are loose on the valves being adjusted at that firing position, valve adjustment has not been done properly (see above).

...After the run, the rockers, some, NOT ALL can be grabbed and have a slight rock. Note - this is subtle and in all cases no wear is detectable on the studs...

I believe this is normal, but others with more experience than I will have to confirm. For those valves with the lifter on the cam base circle, there is no actuation force up the push rod and the valve is in the closed position...there is no load to force the rocker tight against the adjustment nut and some slight clearance should be expected.

Lifters or springs or rockers...

Have you compared your valve noise with other big blocks? Is it possible this is completely normal for engines built within allowable tolerances? You may be able to eliminate that tick by replacing parts, but is it worth it? Unless your friends are noting the noise, I would say forget it...I've found as you age, everything begins to get quieter, even wives.

[Ronald L.]

Re: Late '60s BB hydraulic valves adjust rocker nut down (full turn, 1/2 or 1/4 ?)

Chuck, no the wives don't get any quieter

I have not heard any good 427's recently, the only ones I have seen had a hard time staying running and or were fake big blocks with 65 396 heads and more. Focus was elsewhere at that time on those and I was not so tuned into this, a good suggestion. I have to find a local one that has not been put away for the winter...

[Ronald L.]

Re: Late '60s BB hydraulic valves adjust rocker nut down (full turn, 1/2 or 1/4 ?)

Its getting pretty close to spring time so I have opened up this motor a bit (intake off as well as the valve covers).

This time an answer to an observation from two years ago is finally found, that is the left bank exhaust valves looked different - the left bank have had aftermarket push rods installed.

These aftermarket push rods I'd not expect to be a source of this issue???

Was there a cracking issue with the early 427 OEM rods?

Reason I say that is I have seen this same week a whole bunch of used originals and nearly half have radial cracks and even one a vertical crack.

This is what these 4 AM push rods look like:

http://cgi.ebay.com/ebaymotors/CHEVY-366-427-HIGH-BLOCK-EXHAUST-PUSH-RODS-215-4097-_W0QQcmdZViewItemQQhashZitem483dbc95c7QQitemZ310273414599QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

Is there a potential the lifters are the issue?

Can these been reliably cleaned?

Here is one next to a NOS lifter...[IMG]file:///Users/ronaldlovelace/Desktop/lifters.jpg[/IMG]

[Jack P.]

Re: Late '60s BB hydraulic valves adjust rocker nut down (full turn, 1/2 or 1/4 ?)

Chuck,
I have the CSM, and found the details on the page you mentioned. I did do that, and adjusted all to 1/2 turn beyond the loose point.

The issue is at that point the rockers are tight, do not have any possible rock.

When I run it for more than a half hour, gets really hot, then we pick up on this tick. on going up and down in revolutions.

At that point I added 1/2 turn, and then yesterday, another 1/4 turn.

After the run, the rockers, some, not all can be grabbed and have a slight rock. Note - this is subtle and in all cases no wear is detectable on the studs.


On the L, I recall from buying them in the late 70's that the L stood for Long slot rocker. Chevrolet special perf parts had these and they might not have been a RPO. All mine have an M FWIW and the slotted ball studs are barely worn, they just look broke in on the contact surfaces.

Lifters or springs or rockers...

Hi Ron,

could the tick be lack of valve cover clearance, I had it in my motor just back from rebuild, and I notice the marks on inside of cover. , nut just touches cover. new Hydro lifters and arms , thought they needed adjustment. I replaced standard gasket with thick one, tick gone.

Just a thought

Jack

[Ronald L.]

Re: Late '60s BB hydraulic valves adjust rocker nut down (full turn, 1/2 or 1/4 ?)

Jack, Appreciate any ideas, at the time it had a high clearance valve cover.