I know, there are TONS of threads on valve lash but theyre old and i dont want to resurrect old threads. So many conflicting answers as well (which im sure ill get here too!) I wrote a big thread on Facebook's fiero group, but cannot copy amd paste itbhere as it removes the post button once i paste it.
I had my motor out for a cleanup/gasket replacement. Top intake gasket, intermediate, exhaust etc.
I decided to adjust my valve lash. I followed 3 different manuals (the GM service manual specific for my year,87) chiltons and haynes.
I did everything correctly, found zero lash on proper valves while at TDC for cyl.1, rotatated 360 degrees to cyl 4, and adjusted the rest.
My concern which seems to be mixed answers everywhere, is to seat. I went with what all three books said and didnt bother looking on here prior, which was 1.5 turns. Since these are fine threads, unlike SBC's with coarse threads (one full turn on the stud is 1mm.) I understand the reason for tuning them 1.5 times.
Now that i have the motor assembled amd back in, i was browsing on here, and man oh man are there some conflicting answers! Are all the books wrong? Peopke are claiming 3/4 turns on here is enough. 3/4 turns is enough in a solid lifter with coarse studs as the travel would be equivalent, to 1.5 turns on these fine studs the 2.8's have.
Im just super confused.. Am i ok with the 1.5 turns to center?
Easy way to adjust valve lash and it provides perfect results. Have access to all rocker arms before you start and loosen them all up. Put engine on TDC mark on balancer. Check all rocker arms and adjust for no up down play on the push rods. Just jiggle the push rods up and down by hand until there is no extra movement. Turn balancer 1/4 turn. Now take all play out again for all rockers.Then turn another 1/4 turn and just remove all up down play again for all rockers. Keep doing this every 1/4 turn for two complete rotations of the balancer. Now that all play from the valvetrain is removed, you can just give each rocker arm nut 1/2 turn for the preload. Simple and foolproof.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
Easy way to adjust valve lash and it provides perfect results. Have access to all rocker arms before you start and loosen them all up. Put engine on TDC mark on balancer. Check all rocker arms and adjust for no up down play on the push rods. Just jiggle the push rods up and down by hand until there is no extra movement. Turn balancer 1/4 turn. Now take all play out again for all rockers.Then turn another 1/4 turn and just remove all up down play again for all rockers. Keep doing this every 1/4 turn for two complete rotations of the balancer. Now that all play from the valvetrain is removed, you can just give each rocker arm nut 1/2 turn for the preload. Simple and foolproof.
Thanks dennis! The thing is, ive already assembled everything and put the motor back into the car. I knkw i csn go back in there without engine removal, but ill have to tear it all down again inside the vehicle.. Would you suggest i do that? Or am i ok with having zero lash set, amd tightening 1 1/2 turns like the GM service manual says. Thank you! Appreciate the reply.
Thanks everyone. There was just so many conflicting answers when i searched after adjustment based off of the service manual. I appreciate it!! My mind is at ease now!
I think people recommend less tightening after zero lash, because people tend to over-tighten when finding zero lash.
The first time I set valve lash on my Fiero V6, I only went 1 turn past zero lash, to make sure I didn't accidentally over-tighten them. After the engine broke in, I checked the valve lash and they needed an extra half-turn (to reach the 1.5 turns spec). I was actually glad for that, because it meant I got the zero lash setting correct.
That said, if you're familiar with the process of setting valve lash, or are confident in your ability to follow instructions, then by all means follow the service manual. That's what it's there for.
[This message has been edited by Blacktree (edited 01-28-2019).]
Also some conflicting information is because folks like me have aftermarket valvtrain parts. Like others have said I am sure you did it right with the stock stuff in place.
I went through all this a couple of years ago and posted about it Here.
Hey! Man, i read this thread before taking the valve covers off, and attempted to remove them W/O removing the intermediate intake, and couldnt do it! I tried every which way to get them off and couldnt. I dont know how you did it! I didn't see much about valve lash, maybe i missed it. Ill re-read.
The short answer, is that as long as you properly find zero lash, make more than 1/4 turn, and don't go too far, you are good. The goal with the lash adjustment is to create a hydraulic buffer between the metal stops of the lifter and anywhere from 1/4 to 1 turn will do this. For most daily drivers, you will not be able to tell the difference between 1/4 turn and 1 turn, as they all create the needed hydraulic buffer.
When in doubt, follow the spec for the lifter manufacturer. Over time, the trend has been to make the lash adjustment smaller and smaller.
Thanks guys. I ended up going back in, and redoing the valve lash adjustment one more time, making sure i got zero lash right. I then went 1 full and a 1/4 turn (just incase i was a little off on zero lash) everything seems to be running good! Super quiet! Only ticking i hear is the injectors ( i also have a slight rattle in my ALT. Similar to a TOB rattle. I guess the bearing's are shot, but its not that bad and is still charging correctly. I have another ALT. Laying around that ill eventually put it. Thanks again guys!!
