American Motors: 304 rockers, combustion chambers, fuel compression

Question
#1 What years did not have bridged rockers?
#2 I tightened the nuts holding my rockers on.  Did not torque them, just tightened them pretty tight.  Did I mess up?
#3 Did the early 70's 304's have more horsepower?  I've heard they did and I've heard they didn't.

Thanks in advance,
John

Answer
1) V-8 bridge rockers were used starting in 1974.
2) Tightening your rocker nuts are OK. They are not adjustable.
3) Two things happened in 1971/72 models. SAE changed the way horsepower was calculated and stated, going to NET HP. Second, because of emissions and low lead fuel, compression ratios were dropped, often by enlarging the volume of the combustion chambers. This is what caused the hp to drop.