Adjust valve lash on new heads with installing used rockers?

[dnalbach]

I just bought a set of new heads (good price from a forum member) and they didn't come with new rockers, so the guy provided a set of good condition used rockers with only 36K miles. A friend of mine is telling me that the valve lash will have to be adjusted. Can someone explain that to me?

[robby1870]

Were the rockers the same style that were on the engine before the head swap?

I guess a little more info is needed about what kind of engine, kind of heads, rockers, etc.

[dnalbach]

my bad, it's a 3100 engine on a '95 Olds Cutlass Cruiser (wagon).

block stays, heads are being swapped with a brand new 3400 set. Rockers are the newer fulcrum style stamped steel (no roller tips). Not sure what the old rockers are (ball or fulcrum?), haven't gotten the heads off yet.

[geoffinbc]

Well your car proabably has the old style since the new ones were out in 1996 as best I can remember.

But I believe the pushrods remained the same length so you just need to bolt the rockers down and thats it.

[dnalbach]

This will be my first time, so I'm still a little fuzzy on this. The new heads didn't come with pushrods or rockers, so I got newer ones slightly used. They need to be installed still. When I install them, what length do I bolt the rockers down to? What is the procedure for that? I am reading to do it to touch until there is mild pressure and then like a 1/4 to 1/2 turn? Then once the heads are installed because the pushrods are the same length as the original 3100s there would be no hot lash needed?

[bszopi]

Rockers for the 3x00s are just bolt down and you are done.

Although you will most likely have the stamped rockers, the roller rockers actually debuted in some platforms mid-95.

[geoffinbc]

This will be my first time, so I'm still a little fuzzy on this. The new heads didn't come with pushrods or rockers, so I got newer ones slightly used. They need to be installed still. When I install them, what length do I bolt the rockers down to? What is the procedure for that? I am reading to do it to touch until there is mild pressure and then like a 1/4 to 1/2 turn? Then once the heads are installed because the pushrods are the same length as the original 3100s there would be no hot lash needed?

You need to get educated on all the types of rocker systems

There are 2 adjustment procedures for 2 different systems. You have lash and net lash systems. The net lash system used on Gen II & III motors only requires you to torque down the rocker nut or bolt. Thats it. The whole system is pre built to preload the lifters when installed. Lash systems require you to set lash or preload on the system manually and for each rocker. But in your case you do not need to worry about it.

Serious problems can occur if you try and torque down a lash system. I have seen it done. Luckily the engine usually wont run so people don't end up driving with it adjusted so poorly. Basically the valves will never close and compression never happens.