im thinking about putting a set of 1.6 roller rockers on my car so i can get more lift out of my cam baut i was wondering if this would actually change my idle and powerband or just make more power everywhere, i was thinking no change in idle or powerband because the cam profile isnt actually changing. can anyone shed some light on the subject?

 

It has a very slight effect on effective duration, but not anything to shout about. Mostly you're opening the valves more.

You didn't say anything about your cam, heads, or valve springs, but going from 1.5:1 to 1.6:1 can lead to interference problems in valve travel or spring bind. Make sure you're good to go with the extra lift before you just install them.

 

What about for a stock motor, say a 305 TPI? Would it be a case of just dropping them in? This is under the assumption that the rockers are self-aligning and you won't need guide plates.

Do most roller rockers require screw in studs?

 

The rockers themselves don't require screw-in studs. It's more a matter of spring load, which is typically tied to valve lift.

I've never seen particularly impressive results going from 1.5's to 1.6's. The only time I did it myself was with a rebuilt 350 with 882 heads and an RV cam in the '57 - there wasn't a lick of difference in ET or MPH on the 1/4 mile after the switch.

 

so the verdict is not worth it?

 

Some cams, like the LT4 Hot Cam, were designed for 1.6:1 rockers. They typically don't do that much for you if your cam was designed for 1.5:1.

 

Going from a stamped steel rocker to any roller rocker can be a slightly better power improvement just with the reduced friction.

Going from a 1.5 roller rocker to a 1.6 roller rocker is roughly a 5 HP gain from the increased lift.

Dyno tuning can produce different results. There are times when only putting 1.6 rockers on the intakes is better than changing all 16 rockers to 1.6.

 

I would have never have guessed that, but makes sense. What times are you talking about, stock or mild cams?