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Discussion Starter #1 (Edited)
Hello all - I have a conundrum here. My new complete rebuilt motor for 68' GTO, 400 MT came back with ticking noise I attributed to a loose rocker arm or bad lifter. After numerous consults, I adjusted all the rocker arms per the "twist push rod until tension and snug down 180deg. - NOT the 20lb torques method, even though I had factory 3/8" bottleneck studs. Probably not the best idea - I know that now but with the heads being milled a bit, thought that was likely best. Since the rocker nuts didn't have lock nuts, one came loose after bouncing off the rev limiter (5600rpm) a couple times testing the car out one day through 1st and 2nd gear.
Motor starting clacking again in few miles, then running rough, then belching white and grey smoke, Needless to say - my heart rate skyrocketed and I got her home to garage. When I opened up valve covers to check, I found what is in the picture. I purchased set of ARP 7/16" BB Chev rocker Arm studs, set of #SSR-846RS Rocker Arm kit - Stainless roller for 68 Pontiac GTO from Elgin Industries and installed using this method here.
Pontiac Rocker Arm Adjustment

It does produce a bit of noise at idle clicking wise but I've heard that could be because of roller rocker setup. what I CANNOT figure out is the chugging, stumbling way she runs. timing is fine at 34deg, plug wires all plugged in and tight. when I get on the secondaries, I hear clacking noise and it is definitely not right, so I've put her away. New rocker arms installed are in 2nd photo.

I mean, it runs like I'm down a cylinder - you can feel it.

My question is WTH? Do I have a collapsed lifter from when the #3 intake rocker came loose? Oil pressure never went away, temp never went up during any of these aforementioned scenarios so internally (short block wise) I figure all is well.
 

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Make absolutely certain that you haven't crossed #5 & #7 plug wires. It's REAL easy to do. I've been in a hurry & done it, more than once.

But, it looks like you have your wires separated really well.

I always adjust the rockers by going right down the firing order, doing both valves when that piston is at TDC of it's compression stroke. Both valves MUST be closed at that time. I turn the nut not over 1/4 round past zero lash, then tighten the inner lock screw, then tighten the nut a little more, so that the bottom of the lock screw digs into the top of the stud. This extra tightening will insure that the nut will not back off. Then, I also rotate the crank thru 2 more revolutions, checking the valves on each cyl at TDC of compression stroke, to make sure I didn't miss any.

Others have different ways of doing it. I do it this way so that I will not make a mistake, either leaving out one valve, or adjusting one at the wrong time. Began doing it this way since back in the '70's. Too old to change now. :)

Anyhow, it wouldn't hurt anything to double-check your rocker adjustment, going thru the firing order, one cyl at a time. If your balancer is not marked, you can paint some marks at 90° intervals from the zero mark. That makes it easy to stop the piston very near TDC. My wife painted some marks on mine, with different colored paint. Makes mistakes less likely.

May need to either remove #1 plug and insert a finger, or remove the dist cap, to determine whether #1 or #6 piston is at TDC of it's compression stroke, when your balancer mark is lined up with zero on your timing tab. Either method will work.

This info may seem very elementary to many, or most, here. But, lots of guys have had problems in this area.
 

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Discussion Starter #3
thanks Big D - I plan to check all the plug wires - again - make sure all seated. I also triple checked the #5 & $7 as I too have done that. I believe going back to doing each cylinder at a time is now what I need to do vs. the plan laid out in the link I had in the original post. It had me adjusting 8 valves at a time, then rotating 360 crank deg and doing the other 8. Is this simply not precise enough?

You say 1/4 turn, not 1/2 turn past also so maybe they got too tight? I've never used adjustable/lock nut rockers before. Had the factory ones on both my prior 68 GTO as well. So I'm new to the adjusting game. I did find #1 with the finger in the dike method. when it pushed out, I then rotated motor by hand the last little bit to line up timing mark on harm balancer. wouldn't hurt to check under cap to make positive #1 is indeed lined up when timing mark is at zero on tab.

thanks again for tips. I'll get back and let you know.
 

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Did you pull the pushrod and roll it on a flat surface, like a piece of glass, to make sure the pushrod was not bent?

Generally, no damage should have occurred when a rocker goes sideways - unless it were to push down hard enough on the valve retainer to pop loose/out the split valve locks and you could drop a valve. Take a look just to make sure they are both there.

Sounds to me you have a valve too tight.

The roller rockers are bulky in comparison to the stamped rockers. Make sure you have the needed clearance under the rocker arm-to-spring retainer. In some cases, the spring retainer can hit. You should have as I recall .060" clearance between the spring retainer and the under side of the rocker arm going through full motion. Spring retainers do come in different diameters and heights so as to match the springs. Some won't work with the bulky roller rockers.

Make sure you also have the needed clearances between the spring coils at full lift and the bottom of the spring retainer and valve guide. Again, I think it is about .060" but you can verify this by doing a web search.

Next on the list is to adjust each valve while the engine is running. This has been covered numerous times here, so a search of the forum should find it. You want to "zero lash" each lifter/valve. This ensures they are set correctly and your valves are closing fully.

You should see your pushrods spinning which means your lifters are rotating on the cam lobe. If not, could be an issue.

Did you check your pushrod length to make sure they are correct for your engine seeing you mentioned head milling? Your roller on the end of the rocker arm should be in the middle of the valve stem when the rocker arm is at 1/2 of its lift. If not, the roller could be too far either over the outside (exhaust side) or too far over the inside (intake side) of the valve stem and this will put additional side loading on the valve/valve guide and can speed up the wear process.

Roller rockers should not make any noise any more than stamped rockers:thumbsup: do with hydraulic lifters.
 

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"...You say 1/4 turn, not 1/2 turn past also so maybe they got too tight?..."


Yeah, 1/2 turn is supposed to be OK. But I go no more than 1/4 turn, THEN tighten the outer nut some more AFTER tightening the inner lock screw. So, the nut ends up being somewhere between 1/4 & 1/2 turn past zero lash.

For my bracket engines that had Rhoads lifters, I tightened the inner lock screw at zero lash, then tightened the outer nut a little more. So, for those engines I had less than 1/4 turn past zero lash. But, the Rhoads lifters had real snap ring retainers. The flimsy paperclip wire retainers can easily pop out, if the lifter plunger hits 'em while the engine is running. So, with the wire retainers, I'd go absolutely no less than 1/4 turn, to be safe.

I've never been a fan of the adjust-while-running method. Long before the internet, I heard about doin it that way. Tried it one time. Oil went EVERYWHERE. Some of it shot over the fenders. It was a mess. Learned later that some cut a long slot down the center of an old valve cover, so they could turn the nuts, without so much oil getting everywhere.

Anyhow, once I switched to Rhoads lifters, they make a ticking sound, even when adjusted correctly. So, adjusting while running probably wouldn't work too good with Rhoads.

BUT, PJ can probably describe the best way to do it, if you wanna try it.
 

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Discussion Starter #6
thanks PontiacJim and BigD, push rod has indeed been rolled and checked. - all very good information. A calming influence if you will. After dropping $4k on motor and well over $10k in interior, conv top, wiring harness etc. - let's just say I was getting bit dramatic and frustrated. I will go back and recheck EACH valve separately, do a feeler gauge check on the retainer clearances, and stick with the 1/4 turn past zero lash.

I disussed this with my engine builder who actually says to do all intake one at a time and come back to do all exhaust one at a time. My cam has a bit if duration to it so it helps to have it turned slightly more to ensure being on center lobe? I've attached my motor build/blueprint here as well.

My last question has to do with zero lash concept. I know what it means - it's literally twist pushrods horizontally between thumb and index finger, tighten nut as you do this, and when rod starts to become more difficult to twist (requires more torque to twist) you are at "zero lash". correct? - then the 1/4 turn extra is applied - and tighten the locknut. How much torque on locknut? snug or until it squeaks.

thank you again for all you do for this forum - both of you have many great things you have added.

Joe
 

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gtojoe68: "My last question has to do with zero lash concept. I know what it means - it's literally twist pushrods horizontally between thumb and index finger, tighten nut as you do this, and when rod starts to become more difficult to twist (requires more torque to twist) you are at "zero lash". correct? - then the 1/4 turn extra is applied - and tighten the locknut. How much torque on locknut? snug or until it squeaks."

PJ: You can do it any way you want or what your engine builder says to do. Not the way I "zero lash" the valve train. How will you know which lifter might be pumped with oil and which is not? How will you know your lifter is at its lowest point of travel? How much torque is there in the thumb/forefinger spin? Is the last pushrod going to be the same spin pressure as the first? How do you torque gauge your fingers so each pushrod is consistent?

In the upper right hand corner is "Google Custom Search." Type in "Zero Lash Lifters" to read a few of the posts.

If you had stamped rockers, you would want to purchase a set of Rocker Arm Oil Splash Clips from Summit as pictured. This is what I use when "zero lash" adjusting one side at a time with engine running. Keeps the oil from splashing all over, never an issue with these.

Roller rockers might be a problem. As bigD stated, you could use an old steel Pontiac valve cover and cut out a section to access the rocker arm nuts and have enough metal overhand to cover the oil spurt holes in the roller rockers. Example here:
Also found this on Youtube. Seems to me it would not take much to fashion up a steel/aluminum plate that you could clamp/vice grip at the end/sides of the heads where your valve cover sets on.


gtojoe68: "and tighten the locknut. How much torque on locknut? snug or until it squeaks."

PJ: You are using polylocs, right? It has an allen screw in the center that gets tightened down. So not sure what you are referring to with "tighten the locknut."

Here is what bigD told you to do: I tightened the inner lock screw (allen screw) at zero lash (meaning when you get the valve at zero lash), then tightened the outer nut a little more.

You don't put killer torque on the allen screw or you can strip it out of the polyloc - nice and snug, and something you learn to get a "feel" for. Then you tweak the lock nut using your wrench just to give it a slight twist, maybe 1 /16" or so, just to put a little additional torque on the allen screw. Watch this Youtube video. Jump right to timeline 5:20 and watch until 5:40 to see what this looks like.
Again, too much and you can strip out the allen screw threads, not enough and the polyloc will eventually loosen up over time and back off. So you check once in a while just to be on the safe side. Typically once set, they don't back off.
 

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Discussion Starter #8
thanks PJ -by lock nut I mean poly lock, yes. the allen screw. And I'll go with BigD method. I had it a bit backwards, tightening the rocker nut first 1/2 turn. and then the allen polyloc.

I'll roll through each cylinder at a time, making 90deg marks on the balancer, tightening rocker nut 1/4 turn at zero lash, then inner allen poly loc, then outer rocker nut 1/8 turn more. thus "setting" the polyloc into the stud a bit. If this gives me any trouble - I'll go to the messier route to do while running.
 

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With the small L-shaped allen wrench I use, there is no way I could put enuff torque on the lock screw to strip out the poly-lock threads.

I realize that you can buy allen wrenches with T-handles, and in a socket to use on a ratchet wrench. I can see how the ratchet could easily cause damage. But, I'll continue to use a small L-shaped allen wrench, then tighten the outer nut a bit more, to positively set the screw, on the top of the stud.

About finding zero lash. Lots of different opinions. The rotating-the-pushrod method can get you close. BUT, it can also be a little off, depending on several variables. I grab the rocker arm right over the valve, with the thumb & index finger. With the thumb & index finger of the other hand, I screw the outer nut down, while moving the rocker arm straight up & down. It's easy to find the place where all the slack has been removed, and the rocker arm can no longer be lifted off the valve.

It's easy to back the nut off slightly, till you can raise the rocker slightly, then slowly screw the nut back down, just til all slack is removed. With only light pressure from your thumb & index finger turning the nut, you don't have to worry about over tightening the nut. Doing this several times, back & forth, will give you a feel for how much(or how little) you need to finger-tighten the nut. When all the slack has just barely been removed, that's zero lash.

From this point, I use a box end wrench to tighten the outer nut 1/8 to 1/4 turn. Then tighten the inner lock screw, with my L-shaped allen wrench. Then tighten the outer nut some more, to make sure it doesn't back off. For this last tightening, there is NO set amount ! Depending on what wrench you have, you could probably break a stud, especially a 3/8 bottleneck stud. Each inner lock screw may dig into a particular stud top enuff, with slightly less, or more turning of the nut.

Point is, after tightening the inner lock nut, at the correct setting, tighten the outer nut however much it takes to permanently set the lock screw against the stud top. The total % of a turn that takes can vary slightly, from stud to stud. I've never used a torque wrench to check how much it takes. It's probably less than 1/8 turn. Not sure. I usually tighten it all I can, with one hand, on the short box end wrench I use. I'm not strong enuff to break a 7/16 stud with a normal length box end wrench, with one hand. If you use a ratchet, be careful that you don't go nuts on the amount of torque you put on the poly-locks. Only need enuff to prevent them from backing off.

Most common hyd lifters have plenty of plunger movement, to make up for slight variations in preload settings. Therefore, if all rockers are not adjusted EXACTLY the same, the engine will still run just fine. But, if a rocker is adjusted to where it leaves the valve slightly open, all the time, that's too tight. And, if a rocker is adjusted to where the plunger hits the retainer, and especially if there is slack between the rocker & valve tip, when the valve is closed, that's too loose. Almost any adjustment between these 2 extremes will work OK.

There are different types of hyd lifters. Some have limited plunger travel. The Rhoads V-max lifters, require setting the preload with a feeler gauge. With these, you can regulate how much lift & duration reduction the lifters produce.
 

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Discussion Starter #10
thanks BigD - I did this exactly as you explained, using L Shape allen to precisely avoid over torque. I did play around quite a bit, hand-tighten / loosen up / hand tighten again etc. It is truly a feel thing.

I took out all play, turned nut 1/4 (90deg) turn, snugged down the polyloc, then gave the box wrench a snug to set ployloc on top of the stud. It was different on each - you could feel it set. I would use the word "skosh" to explain how much torque used.

I'm sure it could use a fine-tune someday as my method of finding 90deg marks on the harmonic balancer for moving to each cylinder was decidedly non-conventional. but hey ...it worked. (it involved my wife's sewing cloth measure tape and some good old-fashioned division. A degree wheel would be preferred.

BUT! all good now - went for a cruise last night. Now I just have to get back to adjusting that #%^)@#%^ clutch. *sigh*

As My friend Mark always says..."Dude. It's an old car. Get over it"
 

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So lets wrap this up in summary:

gtojoe68 - ".......what I CANNOT figure out is the chugging, stumbling way she runs. timing is fine at 34deg, plug wires all plugged in and tight. when I get on the secondaries, I hear clacking noise and it is definitely not right, so I've put her away. New rocker arms installed are in 2nd photo. I mean, it runs like I'm down a cylinder - you can feel it. My question is WTH?"

bigD - "Anyhow, it wouldn't hurt anything to double-check your rocker adjustment, going thru the firing order, one cyl at a time."

PJ - "You want to "zero lash" each lifter/valve. This ensures they are set correctly and your valves are closing fully."

End result - Valves correctly adjusted...........engine runs perfect. Valves were most likely adjusted too tight and not fully closing/sealing on at least one cylinder. :thumbsup:
 
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