Whats the proper technique for tightening rockers? Need Help!

[marlowchris]

Guys,
I need to know the proper technique for installing rockers. It is on a 3.4 engine, all stock components. On older engines we used to get the rocker bolts snug, start the engine and finish tightening the bolts until all the rattle was gone. That is not feasible on this engine. Someone said to torque the rockers to 22 ft-lbs and then no other adjustment is needed. The Haynes manual says to find TDC, take out the play then tighten 3/4 more turn. So how should this be done properly? Also when torqued down correctly should you be able to spin the pushrods by hand or should they feel tight with no movement and no spinning? I installed mine per the Haynes manual, they were very tight, I now have a bad miss at idle and suspect this might be my problem. BTW I was replacing the head gaskets.
Thanks for the help.
Chris

[95]

Tighten until all lash is removed from pushrod then tighten 1.5 turns. At top dead you will be able to adjust E-valves 1, 2, and 3. You can also adjust I-vaves 1, 5, and 6. After that turn the engine one time so that the 0 timing mark is aligned. Now you can adjust E-vales 4, 5, and 6. You can also adjust I-valves 2, 3, and 4.

[marlowchris]

That is the sequence I used, but I turned them only 3/4 turn after removing the lash. This felt too tight to me. I am thinking of loosening them and only turning 1/4 turn. Have you used the 1.5 turn method before will sucess? Thanks for the help.

[95]

Never done a v6 but I've done my Lt1 with a 1 turn after all valve lash was removed and it was a sucess.

[marlowchris]

I am not sure that the 1 turn is true for all engines. On my Corvette LS1, I tourqued them down to 22 ft-lbs. 22 ft-lbs would make the rockers on the V6 extremely tight. I think it might depend somewhat on the type of rocker, thread pitch of the stud,etc. I am going to reassemble the rockers with 1/4 turn, which is about 7 ft-lbs. That makes the pushrod feel about right anyway. If it rattles, I guess I get to tear it down and tighten them more.
Thanks

[95]

All LS1s have a stoping point unless using crane adjustible rokers. LS1s get away with no adjustment because aftermarket cams use the same base circle as the stock cam and the stoping point stays the same so all they need is to be torqued down, but this does not hold true for older small block chevys or the v6s. We still have to adjust them.

You can take out all lash then tighten and count the turns it takes to bottom out the lifter you can tell its at the bottom because it gets real tight. Then back it out half the turns you counted and the plunger is at center in the lifter. done ;)

[marlowchris]

That makes since about the LS1 having stops. But when you said tighten it until the lifter bottoms out, then back out half the turns. Did you mean to say the valve. The lifter rests on the cam and is not going to move down. When tightening the rocker beyond removing the lash, the valve spring will compress moving the valve down. I guess if you turned enough the valve would bottom out. Thanks for the help.

[95]

The lifter has a hydrolic plunger that is pushed down by the pushrod it will bottom out then it gets tight and the spring will begin to compress and the valve will begin to open if you keep tightening. Thats why they call them hydrolic lifters. Count the turns it took to bottom out and then back it out half that amount and they are set.

[marlowchris]

I understand what you are saying now. For some reson I was thinking solid lifters, not hydraulic. Thats makes perfect sense now. Thanks for all the help. I am going to finish it tonight.
Thanks again.
Chris

[Lord_Verminaard]

Not to bounce off topic much, but dont the 3.8's have the same rockers as LS1's and therefore all you do is tighten them down to a certain spec? I know you were asking about the 3.4 but since everyone was talking about it I figured I would ask. Thanks!

Brendan
2000 Camaro L36 M49