i appreciate your concern. I know I’m asking basic questions, but I’m pretty good at following directions and figuring things out. I’ve watched several videos and read several guides and I’m feeling pretty confident I can do this. Watching the video in the linked thread in my first post really helped me to visualize it.

Six years ago I had really never worked on a car. I got fed up paying mechanics to do half assed jobs so I just started watching YouTube videos and doing stuff myself. The first thing I did when I got this car was to swap the injectors out, for instance.

all that to say, I really appreciate the help, and I’m inexperienced with valves work-but the only way to get better is to do it, which is how I’ve gotten to where I am. All of the answers in this thread will get me there-and next time I won’t have to ask basic questions!

 

If you're going to go through all the trouble involved, at least consider a valve spring upgrade while you're at it if a cam swap is a potential future consideration.

 

what makes a valve spring better? I’m sure my current ones are worn but what would I get besides an OEM replacement to upgrade?

 

Unless I have to, I usually give the mechanic a small job and watch him. If he is any good I might see about tipping down the road. Buying him coffee, donuts, asking him to clean out the ashtray with an envelope, etc.

Also hiring him to teach you works often. I read up on the job and have you show me how to do it and I try in front of you.

 

Maybe give Crower or Comp Cams a call. They may be able to make a recommendation on a spring that works better than stock for higher lift that DOES NOT require machining the pockets they sit in

 

Hello again Bfenty!

When I rebuilt my 427 I bought a Cam from Comp Cams. They had a suggestions for springs and their settings. My engine builder and I spent hours working on the cylinder heads on each cylinder. He would measure the strength of the spring and then shim it appropriately to get exactly the correct amount of pressure when they were open or closed. Each spring took a while to set up correctly, some folks just take them out of the box and use them. My builder was a detail minded guy and worked for Porsche during the Can Am days. He knew a lot of places that you could find more power.

Some springs today are shaped like a Bee-Hive and that makes sense when you watch a high lift rocker arm bind the spring. I used expensive springs that would not bind at the levels I used them. At the time I built my engine they were pushing dual springs for each valve. I ended up using a single spring per valve. Each Spring and valve assembly took maybe 15-45 minutes each to set up properly. Trying to get the seat pressure correct and the compressed spring power is what requires shims and experience. There were several tools that my Buddy had for making the installation easier. I just remember watching him as he measured the springs with a Micrometer and he measured them several times until he was "satisfied".

Replacing the Valve Seals is not that hard compared to setting up a cylinder head the first time with new springs or other parts. Once you do one cylinder you will become a pro and have no issues with the resat of the valves. Just think what this job would be like on a ZR-1 engine? They have 32 valves to get set-up... Be sure to have a small magnet ready to assist you removing the parts as fingers get to be too big to fit.

Adjusting the lash is no big thing unless you have solid lifters. I have been doing that since the mid 1970's and have gotten pretty good at it. Be sure to plug any hole or passage with clean rags to keep parts from falling into your engine.

As I said before YOU are "Prepared" for this experience and we are here to help you in any way. If you have any problems you have a big group of supporters here who will help you!

 

Well, I did it. It’s all back together. And there’s a tick! Ugh. Driver side, one of the back two cylinders. Not sure which one yet. Haven’t taken it apart yet. I’m pretty sure we got it all tightened back down. I’m assuming that’s a rocker arm?

 

Rocker would sound more like a tap than a tick imo.

Do the hot running lash on the valves. Back off until it taps. Let it sit a minute. Tightness until the tap just goes away and then throw half a turn on it. Its likely one was just a little loose.

 

could also be called a tap probably.

it definitely wasn’t there before I did the valve seals, and it is now. Only thing I did was what was necessary on valve seals. I can’t imagine any other moving parts that would be doing it.

my plan is to take off the cover on the drivers side and run the engine like that for a minute. Hopefully I can see or hear something obvious at that point.

Edit: missed the second half of your comment, that’s pretty much my plan

 

Note: FSM says a full turn past pushrod being tight, but I see people saying here it’s a half turn. Which is it??? I’m leaning towards following the FSM and that’s what I did.

 

Full turn means you probably never have to open it up again. You allegedly get a bit more power with less preload though.

 

Thanks. That helps.

 

Please explain how that would make any difference.

 

i would have to guess less resistance? Just guessing.

 

I have literally no clue. I know on solid lifters running the lash a bit loose will pick up some power but on a hydraulic i could never wrap my head around it. My only guess is less losses trying to pump up the lifter but again. You're talking miniscule. My lifters actually wanted you to calculate preload by TPI on the threads of the rockers and set it that way. It ended up being about 3/4 turn to set it correctly.

 

On other thing that I noticed doing this job-the seals on one side were in considerably better shape than the other (drivers were in much better shape than passengers). They still looked OEM though, so not sure if they were replaced? Also, the valve springs had a second spring inside them, which I don't see on many of the aftermarket OEM replacement springs. Is that stock? I don't have a service history of the vehicle, trying to infer what it might be.

 

Bf - not sure where you're at in this endeavor, but I like to add in my 2-cents...

1) FSM IS A MUST - PERIOD!
2) i'm not a big fan of shouving anything in the cylinders of my engines - I only use compressed air. obviously you need a compressor and a spark plug hose adapter fitting.
my method of valve stem seal replacement (heads on engine) - remove all the plugs and remove ALL rocker arms, adjusting nuts, etc. pressurizing the cylinder will force the piston to BDC - a constant 125 PSI will keep the valves against the seats. pressurize one cylinder at a time. don't rush this job and be ****.
3) a simple lever arm valve spring compressor tool is all you need. a magnetic pickup tool to capture the locks is really handy.
4) when removing rocker arms, springs, retainers, locks, etc. - be detail oriented, systematic, and methodical - all parts in their original location and original orientation. try not to introduce anything new into the equation. L98's are designed for low RPM performance - if less than 100K miles, most likely your springs are OK - you can check the specs or have them checked, but if you need or want to replace them, standard SBC springs are readily available. DO NOT go overboard on spring rates stay close to factory specs. I suggest Elgin Industries. Elgin is a tier one supplier to GM - chances are your originals are Elgin parts. you can buy these things on fleabay all day long for around $40/set. currently running elgin valves and springs in my 85 - 13K miles - zero issues.
5) fel-pro for new seals
6) valve adjustment - SBC's will pretty much run anywhere from 1/4 turn to 1-1/4 turn on the adjusting nut. the factory usually states 1 full turn (and I once read there's a reason for that), anyway, inside the hydraulic lifter is a small plunger - basically a spring and small ball bearing. for the most part, the plunger travel is around .060" and ideally, you want to adjust the valves at the halfway or mid point of that travel, or .030" from zero lash - the sweet spot. 3/4 turn pretty much hits that sweet spot. in a perfect world, adjust your valves to the mid-point and EVENLY across all 16 valves. I don't rely on the "spin the pushrod until resistance is felt" method - to me, too subjective. I set "(near)zero" lash using a .0015 feeler gauge. follow the FSM for the procedure and sequence - absolutely no reason to over think this.

again, this is my 2-cents - FWIW....

 

Well, one of the rockers was completely loose-I guess I missed one?

I tightened it down, but now I'm getting a misfire at partial throttle, WOT seems to be running on all cylinders still. I'm assuming that means a valve isn't opening wide enough, which means I didn't tighten them enough? It also idles kinda rough. I followed the FSM pushrod twist method, followed by a full turn on each. Engine is too hot to work on right now, but this is really frustrating...any thoughts? It was running great before I did this job, just losing a little oil, so I'm pretty sure it's something I did specifically with the rockers/valves. I also pulled out the spark plugs, but...I doubt that's it?

 

I did a hot adjustment of the rockers. Some had two full turns before they loosened up. Made a huge mess in the garage with oil, but now she’s purring-sounds better than when I started the job! I’m actually betting some of the valves weren’t adjusted properly before I started.

thanks everyone for the help! I’ll post some photos from the job later and a few lessons learned, to help future forum users.

 

Hot is the way to go if you don't mind a little mess and have the time IMO. The twist method can give varying results, as you sort of saw. IIRC the old FSM stated to redo it hot for final adjustment. I've always done for initial: lift up and down on pushrod. Slowly tighten nut until you can't feel or hear it moving against the plunger. Do 1/2 to 3/4 turn from that point. When I've gone back in for the hot lash after it was usually spot on or really close... Depends how **** I was feeling that day.