series 1 to series2

[89vn5speed]

got a problem here. im gunna replace the pushrods etc in the ol 6 but my question is can i access the lifters from on top without removel of the timing case etc coz i dont wanna piss ass around with it, also while im here does anyone know if i can use the lifters, pushrods, and rockers from a 1991 engine and slap em in a 1989 engine. thanks in advance

[Shaun_VK]

Not to sure on the lifters, but I know you cant put series 2 rockers onto a series 1, the threads in the heads are a different size.

Hope that helps.

[Jxw]

you'll need to remove the intake manifold to access the lifters, not a bad thing as freshening up the intake gaskets can't hurt, they're prone to eventually cracking and leaking water into the intake (plastic with silicon impregnated) drain the coolant properly first, pull the hose off the pump as it sits lower than the water jackets in the heads and let it drain before removal.

it probably won't hurt stripping the top off and you can degrease/remove all the old oil sludge/buildup that tends to be found in the top end of these engines, especially high km/old ones... see pic below

the lifters and pushrods will swap over fine, you may find the lifters hard to remove but they do come out, it'll be varnish/sludge built up stopping removal, it builds up in the oil gallery where the lifter isn't running up/down against the block closely, you can shove a flat blade screw driver into the ridge where the gap in the retainer clip is and work them out (carefully not to damage the U clip) or grap them with some pliers/multigrips(not vice grips) and work them clockwise/anticlockwise while lifting up, they're a pretty tough metal compound so shouldn't cause damage, if you do manage to burr the edges... use some emery paper to smooth it out before reinstalling if using them again.

if changing the rocker gear you'll need to use the guide plates under the rockers gear in the head from the s2 engine on the s2 rockers as they're a different thickness from memory.
so don't mix up the rockers, pivots and plates. same size bolts etc etc

but I know you cant put series 2 rockers onto a series 1, the threads in the heads are a different size.

Wrong, vn s1, s2 and vp use the same bolts & threads in the head to hold the rocker gear on.
S2 heads are slightly different in the water jackets going to the block, 2 holes less & have an extra hole that lines up on the s2 manifold for pcv system
(in the top left of the pic below you can see i've drilled a s1 head to use the s2 intake manifold).
That's it for differences, you'll find the same casting numbers on s1 & s2 heads sometimes with two minor differences between them.
Easier & cheaper for gm to drill 1 hole instead of 2 than recasting the entire head.
VR roller rockers use smaller diameter bolts to hold them in as they have 2 roller bearings stuck on and limits the space for the hole/bolt, you can't put VR rockers on a vn/vp head easily. (you could plug the hole with a bolt, re-drill and tap to the correct thread)

You may have a large metal splash shield with 6 figure 8 guides locating the lifters instead of the 2 long plastic bits (from a vr engine) as they're keyed to keep the roller running along the cam properly.



and gm's great idea for a gasket