Hello, recently replaced valve stem seals and have questions about setting adjusting rockers for lash. 1971 L46, sounds stock to my ears (I've never taken engine apart), there's small movement to pushrods when pushing down, so I'm assuming hydraulic lifters.
I did the adjustment per Lars paper. While doing i found the #1 intake pushrod to be bent pretty good. All others checked good. I've replaced that rod.
After doing the adjustment, I've found the #4 intake rocker to now be very loose after doing the adjustment. I also pushed down on some pushrods to see how they were and some have give and some don't. The engine hasn't been started since fall last year and I'm thinking some of the lifters may have bled down.
So my questions are: Do I go through and loosen all the rockers and adjust again? Could that loose #4 have been "forced" to bleed down by the adjustment and subsequent engine rotation when I did the other valves? Is it normal to have some movement on some pushrods and none on others? Is it safe to start engine thinking those lifters will pump up? I just don't want to blow anything up here.

 

The big question that I see is HOW are the push rods being bent in the first place? What procedure did you follow to put the parts back together after replacing the valve seals? When did the bent #1 push rod happen? Any ideas on just How it happened?

When I re-assembled the top end on my engine I start by rotating the engine until it is at TDC for cylinder #1. At this time both valves should be closed and this should be verified just to be absolutely "sure" of where you are starting. Then I install the pushrod and rocker arm in place and start tightening them up very slowly and carefully. When the push rod stops spinning easily (between two fingers only) then it should be close to a zero gap. From here you need to tighten the lock nut for 1/2 to 3/4 turn (only) to get the correct pre-load on the lifter.
If you tighten it too much then you might bend parts like push-rods and if it is too loose then you will have a lot of noise coming from the lifter. Once the lifters have the right amount of pre-load on them, the push rods should not turn "easily", they are supposed to have some load on them which would make it harder to spin them with your fingers. The order in which you do the rock arm setup should be carefully followed. I do it the hard way and spin the engine over according to the firing order to get the next cylinder in line and ready to set.

Many people like to use the little 'clip on' oil blockers to keep the oil from splashing on to the top end from making a big mess. Personally I chose to re-use an old valve cover from my BB. I cut the center of the valve cover open allowing me to access the hardware from above without loosing quarts of oil doing it. The open valve cover needs to be cut so you have good access to the rocker arms and nuts and nothing more. This method is the best I have tried in my days of tinkering. You don't have to de-grease the engine when you finish up... I wipe down the old valve cover and put it back on the shelf for next time.

Do you have a GM style Oil Pump tool that allows you to spin the oil pump using a shaft inside a modified, shorter distributor housing with the top cut off? I have one and I use it when I get ready to start an engine after it has sat for a while. With this tool I can see 30-45 psi inside the lubricating system (as long as there IS oil inside the engine) on the gauge of the dashboard with the drill spinning at near full speed. I personally use a Corded drill because the load is high and batteries can wear out before I am done. By forcing the engine to have oil pressure is a good thing but you are not done yet. I remove the spark plugs and slowly turn the engine another 1/2 to 3/4 turn before using the pre-lubbing tool again in this engine position, this ensure that the oil has traveled in most of the passageways and it is pre-lubricated with fresh oil prior to re-starting the engine. Once this is done I would assume that the lifters have been "charged up" with fresh oil and ready for the tightening sequence.

Once the engine has been pre-lubed then I install the valve covers with the hole in them. With the engine warmed up and the rocker arms exposed they should all be nice and quiet if and when the lifters are set up correctly. I snug the nuts down after the engine is shut down.

Are you using the oil with extra zinc in it to protect your camshaft from being wiped? Do you have the tools needed to check the height of the cam shaft lobes inside the engine? If the push rods or the rocker arms are loosening up that is not a good thing. Something has to wear funny to allow that to happen. Once the lifters are pre-loaded and things are in order the adjustment should last for thousands and thousands of miles without making any noises or having parts come loose.

Check all the push rods and remember where they came from. Lay them on a flat surface and ensure that they are all straight as an arrow or replace the set. What did you use to hold the valves in the closed positions while you changed the valve seals?

 

hoooBoy! I just went through this "springy" feel discussion on my BB. Yes, I believe the soft lifters have bled down. Set them all according to whatever method you prefer, just make sure you're setting every one when it's on the base circle of the camshaft. Start the engine and let it run for 5 minutes or so. This will fully oil the lifters and quiet any that were not pumped up - if none are clacking, all's good. If you hear clattering, shut it down and go through them all again without backing the nuts off. At this stage, the springiness is likely completely gone and you're just looking for the lifter(s) that have loose push rods to adjust further. (Rod rotation isn't a good indicator, what you are looking for is up/down movement between the rocker and lifter cups.) The slight springiness makes this a little more challenging, but the nut preload takes care of this.

Here's the whole thread:
https://www.corvetteforum.com/forums...post1608665519

 

For years & years we were taught to spin the pushrod, swing the ratchet until the rod stopped turning.

As said above, that method gives false lash readings. Even a valvetrain that has the correct lash set just minutes ago or years ago will allow the pushrod to rotate.
So what did you do? Torque it down some more. And more. Now your valves won't close. The plunger inside the lifter is bottomed-out.

The newer, more accurate and pretty much foolproof method is to just try to move the pushrod up & down.
That's all. Very simple. No spin, no fingers turning. No do-overs.
Just take the up / down slack out. No more. That is zero lash.
Then add half a turn.
The plunger in the lifter will be centered in its travel = perfect!

 

I have always struggled with feeling slack on my 454 because A) #3,5,4,6 intake push rods are very hard to get fingers on due to where they are and the closeness of the intake runners and 2) everything is oily and slippery. When I did my engine a month ago after replacing a set of push rods, I discovered that I could use the rockers themselves to feel for any gap. Using two hands, lifting the rocker up against the ball and gently pivoting the rocker between the rod and valve tip I could easily feel if there was slack. The gap was evident at both contact points, so it was positive feedback to set the zero point and I could feel it in both hands rather than just one lifting up and down on a pushrod. With the few lifters that weren't pumped up, I could also see when the "zero" point was pushing the spring and to stop just then.

 

I did check all the push rods one by one on an inspection plate, there was just the one bent. I used rope to hold the valves up, i was afraid to use air. (Don't trust my compressor)

 

This tracks....I felt like they were spinning really easy loooong after the up and down movement was gone.
I'm still wondering if it's normal that the #4 is loose after tightening all the other ones. If they're a little loose and I let it just idle, will I damage anything? I'd think I wouldn't get float or bend anything. I may bite it and buy some shitty used covers to chop up.

 

Depending on where the #4 lifter was on the lobe, it may have just been slightly elevated when you adjusted the preload. The rocker studs are 24tpi, so each 1/4 turn = 0.010" of downward movement. It doesn't take much lifter height to mask that amount of space if you were on the lobe at all.

As long as the rocker is not so loose as to allow the pushrod end to jump around in/out of its cup, running for a short time won't harm anything. When adjusting running/hot, you back off the nuts until they clatter and tighten to being quiet to reach the zero point. This is much the same. You don't want to let the clattering go for miles and miles because the open slack is allowing the parts to bang into each other rather than smoothly push.

Also depending on what sort of oil pump and rockers you have, adjusting hot (even with cut-away valve covers) could be a royal mess. My engine can spurt oil over the fenders - no cut-away valve cover is going to stop that.

 

Use the push rod "shake" method, rather than the "spin" method, if you are not expert at this process. Also remember that there are TWO TDC positions: compression stroke and exhaust stroke. You must do your adjustments on the compression stroke. Or, as mentioned by others, just make sure that any lifters you adjust are on the base circle of the cam, NOT anywhere on the lobe. If you just watch the action of the pushrod and rotate engine a bit past where rod drops back to the base circle on the cam, you should be fine.

 

I believe that the #1 intake push rod was bent due to over-adjustment using the "spin" method. In my younger years, the spin method was widely used and I realized that I could pass the zero lash point very easily at times and finding zero lash was difficult under those circumstances.

 

Thank you to all who replied, I will be starting the car tomorrow after doing the "up and down" movement adjustment + 1/2 turn following Lars' directions but up down vs spinning. I did get some crappy covers (for free! from a good dude named Chris Zigrossi who sells Vette parts on ebay and Facebook. He's a good guy and not a scammer) and chopped the tops off. I'm hoping to not make a mess.
I am expecting some tapping at 1st, then it should quiet down like my Harley did when I did the new cam and lifters in it. Crossing my fingers! Thx again!

 

There is very little reason to set hydraulic lifters with engine running. Do it if you wish, but pretty much a waste of time, IMO. The main value of hydraulic lifters is that they 'absorb' some minor adjustment errors.

 

So the "up and down movement until they just stop, then 1/2 turn" worked great!! Got a bunch of ticking from a few lifters that had gotten a little too tight on the 1st go round and leaked down. Then it quieted down. I did run for several minutes with the chopped top valve covers and checked a couple rockers with the "loosen till clatter, then tighten till just quiet, then 1/2 turn" method and confirmed i was good to go. I checked my timing and just finished tuning my carb. I can't say enough good things about that Lars guy and others on here who helped me! Thanks everyone!!

 

 

 

Lotta time; lotta work to make those covers. Nice work. Very necessary, if you had solid lifters. Not really needed for hydraulic lifters. BUT, I will agree that setting them that way will optimize their adjustment.

 

my cut off covers look nothing like that, LOL! It took about 5 minutes to chop mine up. I wore good gloves to handle sharp edges! They worked though! I had almost no oil go splashing around

 

Solid lifters should never be adjusted with engine running and must be lashed with a Feeler Gauge. Very time consuming and tedious but must be precise, allowing for heat expansion or contraction.

Hydraulic lifters on the other hand, have a lot more leeway and forgiving lash with several thousandths of an inch play. The plunger will make up the difference when running.

 

@67:72,
In your situation it might be easier to use the feeler guage method. Just slip the thinnest. 002" or as thin as you have between the valve stem and the rocker tip. Tighten the nut just until you can sense the feeler guage getting snuggly, then pull it out and tighten another half turn. This still requires you to have the engine at #1TDC Firing position to do the first 8 valves then rotate 360 degrees to #6 TDC Firing position to do the last 8 valves. Hope this helps.

 

Thanks to all who replied. I used a combo of Lars and up and down wiggle and triple checked with cut open covers. It's running very smooth and only get a little smoke now instead of chooching out like a steam train. I completely redid timing and tuned the carb...so much better. Runs very cool now too. On to the body mounts and the rest of the weatherstripping and the front frame straightening and...and...and....LOL!!