I'm in the middle of my cam swap and I'm trying to install the new LS7 lifters, trickflow 7.150" pushrods, and 1.6 pro mag roller rockers. I went to TDC on cylinder 1 and tightened the rocker nut until the pushrod slack is gone. I then tried to go antother 1/2 turn. The nut will not tighten another 1/2 turn. It appears that some of the lifter plungers are stuck. The plunger will not move down. Some of the lifters are ok and have plenty of give in the plunger while others dont seem to budge. How can I adjust the rockers for zero lash if I can't tightening them anymore? How can I unstick a stuck lifter?

I currently have them soaking in oil but that is not helping. I also pulled the clip off one of them to see why it is stuck. It is so tight I'm not sure if I can get the clip back on. Any ideas?

I really need to get this all back together by Monday.

Thanks

 

Rick,
I'm not familiar with the "new" LS7 lifters....but basically it sounds like you've got them too tight and they have bottomed out.
The oil can leak out of the lifter since it is only held in by a non super great sealing plunger inside the lifter itself. If the engine was cold, which I'm sure it was, when you did the lifter install the oil had a chance to leak out/down so there was nothing there other than the light internal spring pressure to offer resistance to the pushrod seat. The oil pressure from a running engine working in conjunction with both the lifter's internal seal and spring to provide the "oil cushion" for the pushrod. Here is a link to provide a better basic description of internal cam parts and functions:http://www.chevyhiperformance.com/te...ide/index.html

It is not necessary to “pre-pump” hydraulic lifters full of engine oil prior to installation and valve adjustment. It is actually undesirable to do so as the “pumped up” lifters will cause the valves to open during the adjustment process, rather than positioning the valve lifter plunger in its operating position as it is supposed to do. “Pre-soaking” hydraulic lifters in a bath of engine oil is a good idea, but it is not mandatory. It does ensure that the lifters are adequately lubricated on their outer surfaces prior to installation in the engine. It may also result in a quieter engine start up as the oil in the bath may displace some air from the lifter’s plunger reservoir. Below is a basic picture of what the internals of a hydrolic lifter looks like:


If your concerned that you over tightened your lifters simply back them off at the (rocker) retaining nut and start again.

Put the cam in the proper postion find zero lash and adjust each rocker nut only once with the correct amount of preload....then move on. I usually only do about a 1/4 to 1/2 turn for preload myself....CF opinions vary on this amount of preload.....but I stick with what I was taught and have had past success with.

Good luck with the project!

 

EDIT: I'm glad it all worked out. I had never heard of that problem.

 

I fixed the original post the pushrods I have are 7.150". I measured for them before ordering.

Ok, I think I have it figured out. Based on what many have said I was probably way over complicating things. When I went to tighten the first two rocker arm nuts I was comparing the two together and how the lifters reacted to the tightening. One was very easy to tighten even for the half past zero lash. The other was extremely hard to tighten almost to the point where it would not go half past. I had pulled both lifters out and the one that was easy to tighten was also easy to push the plunger in. It went in 1/4". I thought the plunger on the other lifter was stuck because it would not move in at all. I checked all 14 other lifters and their plungers also could not be pushed it. I tried with the old pushrod against a brick wall while putting all my weight behind the lifter. I went to two dealerships. One had 10 lifters and 4 of those pushed in 1/4" and the others appeard to be also be stuck. I went to another dealership that had 6 lifters. All of those would not push in. When I got home I checked the stock lifters and those plungers also could not be pushed in. So I had now checked 48 lifters and out of those only 5 plungers could be pushed in 1/4" and 43 did not move. I'm guessing this may be normal and most people probably don't even look at the plunger before installing. When I got back home I tried to again install the LS7 lifters and I was able to get them all in and set 1/2 past zero. They had been soaking in oil all morning also but I don't this mattered. 15 of them were pretty tight on the 1/2 turn and that same one was easier then the rest. I'm pretty sure though everything will be fine. I don't understand the difference in plunger tension on the lifters. I thought maybe the ones I had were sitting on the shelf too long and were bad. I think I was over complicating things trying to avoid any mistakes.

 

I believe most lsx guys dont run much more than 1/8-1/4 turn with these. I ran about 1/4 turn.

Some of mine were like that to when it comes to the plunger. They were hard to push in at first, but they 'broke in' as time went on. As long as you are doing the rocker lash right (i do the intake closing/exhaust opening technique) they will be fine once they pump up.

Dont have to presoak them, just put some oil on the roller tips and needle bearings on the roller. Have to put oil in there and move the roller wheel back and forth to get all the oil on the needle bearings. You may have noticed the roller was hard to move when you first opened the box. Place some oil on the needle bearings/roller and move it back and forth, it will loosen up and be ready to run