1.5:1
They are pressed in.
The stock rocker arm ratio for a Gen I Chevy small block is 1.5:1. The marine engines have the same rocker ratio, but use different cams and have bottom ends built to handle sustained RPMs.
In 89, Chevy introduced the 1st generation vortec head. It has a different angle, thus using a different intake manifold, and self adjusting rocker arm.
There are no provisions for valve adjustments on this engine. Tighten rocker arm nuts to 20 ft lbs torque and you're done.
A rocker arm shaft is normally a long shaft with rocker arms attached to it, that provides the pivet point for the rocker arms (newer Chevy motors).
yes
24 foot pounds
A rocker arm shaft is normally a long shaft with rocker arms attached to it, that provides the pivet point for the rocker arms (newer Chevy motors).
Some combinations might benefit from this. Difficult to evaluate without a dyno.
The rocker arm ratio (whether they be stock or roller rockers) has to do with the offset of the rocker fulcrum. The stock rocker ratio on the small block Chevy is 1.5:1. This is important because it effects your valve lift. For example, a camshaft with .300 lobe lift will yield a .450 valve lift with the stock 1.5 ratio rockers. Multiply the lobe lift times the rocker ratio to get your valve lift. Now, that same camshaft will yield .480 lift with a 1.6 ratio rocker arm and .510 lift with a 1.7 ratio rocker arm. More lift is good as long as your valve springs can handle the extra lift and you don't run into valve/piston interference problems. You are more likely to run into coil bind with the valve springs than an interference problem though. When in doubt, make sure to check just to make sure there will be no problems.
The correct torque for the rocker arm bolt is 14 N·m (124 lb in) plus 30 degrees.
The 2000 Chevy Impala 3.4 liter engine rocker arm bolt torque specification is 45 pounds. The rocker arm bolts should be torqued in 15 pound intervals.