Im working on a top end rebuild on my 86 IROC and Im at the point of checking for pushrod length. So,I tried the pushrods that came in my engine (there not stock) tonight to see if they would work with my heads and cam. I'm using hydraulic lifters

So, I adjusted lash CORRECTLY, turned the engine over a few times, and just to be sure I checked my lash again but I could spin both intake and exhaust pushrods! SO, I adjusted lash again (ABSOLUTELY NO PUSHROD MOVEMENT) proceeded to turn engine over few times, and It happened again! I adjusted lash AGAIN, tuned over a few times, and found play in pushrods! I did this process 6 times before I could turn the engine over an infinite amount of times and maintain the lash.
I also noticed that by the time I was done, the top of the lifters were further down in the lifter itself than the ones I had waiting to go in the engine.

So is this just me making a mistake in procedure or should I have just set the lash the first time and forgot about it?

 

Some of the pushrods will be loose... Or are you just checking a specific cylinder?

 

I was just checking to see if those pushrods were long enough so id have the proper rocker-valve tip contact pattern. And i was just checking Cly#1.
So its normal then? Im assuming that the play should be taken care of when I prime the oil pump, correct?

 

You shouldnt adjust the lash until the rods wont turn at all. You should adjust the nut until you JUST feel LIGHT tension on the rod when trying to turn, then turn the specified amount. At this point you should still be able to turn the pushrod with a bit of effort, if it doesnt turn at all or you gotta work your butt off to turn it, then you probably have it too tight.

Your best off to adjust the lash with engine running.

Also keep in mind that without the engine running the lifters cant use oil pressure to maintain lash, and therefore WILL increase lash. You should set the lash ONCE and leave it, then if your concerned, then once engine is running you can adjust them hot with it running and that will give you peace of mind.

 

Thanks for the quick replies. hgffrank, whats really confusing me is ive prolly heard 30 different ways to adjust valve lash. And i have been told to tighten rocker nut till no push rod movement, but i trust you online folks more than real life people anyway...
So, to do it right. I tighten rocker arm nut till SLIGHT drag is felt while spinning pushrod, then turn nut another half tun, correct?

 

Yup. As long as you're on the base circle of the cam.

 

Yeah I agree there are alot of idiots who THINK they know how to adjust lash but not many Actually do. People over think stuff too much, I like the K.I.S.S method. KEEP IT SIMPLE STUPID.

The purpose of spinning the rod is to get to 0 lash. The definition of 0 lash is no movement of pushrod UP AND DOWN between the rocker and lifter. So the method of spinning the rod has only one purpose: to let you know when the rod is contacting the rocker and the lifter, which is 0 lash. So the exact point you feel slight tension when trying to turn the rod mean its touching at both ends, hence 0 lash. At this point you would then turn your additional 1/2 turn if thats your spec. DO NOT readjust until running and oil has reached the lifters and filled them. Hydraulic lifters use oil to MAINTAIN lash. If you dont have any oil in them, then they CANT maintain lash, which is what you experienced.

Also its a really good idea that when installing lifters you should immerse them in oil for an hour of two before installing and then be sure to use assembly lube on the bottom. most people dont do this and its just one of them things where it will come back to bite a few out of a hundred. But I gotta tell you, its cheap insurance and I wouldnt wanna be one of them few who wiped out a cam cause I was too lazy to do it right.

 

This takes a while but is fullproof.Attachment 139842

 

I used this: http://www.compcams.com/Technical/In.../Files/250.pdf
I hate setting lash with the engine not running but without an exhaust it kinda makes it difficult to hear the tapping.

 

I agree. I tried that once with bad results. I ended up lightly clamping a couple spare mufflers I had onto the headers and that helped enough for me to do the lash right.

 

I tried that. I had my headers, s-extensions, and chambered mufflers bolted up. Unfortunately though chambered mufflers don't really muffle all that much. Still couldn't hear the tapping. Although there was a noticeable difference between all 3 pieces and just the headers and extensions.

 

Thanks for all the replies guys. Once this thing actually runs ill defenetly readjust running.
But ive run into another snag. I got my valve train assembled tonight and was hoping to get the lash adjusted also. But, I reused the roller-tipped rockers I discovered someone had put on this engine before. The problem is when trying to set lash, my socket(Craftsman) is always getting hung up on the inside of the rocker as i attempt to turn the rocker nut, making the rocker kinda pivot to on side.SO, when i think ive got 0 lash, ill pull the socket off and theyll be a a lil up and down play.
This led me to the decision to get some ARP poly-locks because A) There obviously superior to regular self locking nuts. B) There point on contact with a wrench is well above the rocker
But i went on Summits website and the only rocker nuts that show up for roller tipped rockers are the self-locking(stock) style.

So after all your time reading pretty useless side-info, can a poly-lock be used with roller-tipped rockers safely?

 

I don't see why not although i've never heard yay or nay on the subject. Why don't you just get a thin-wall socket?