Let's talk changing non-adjustable rockers to adjustable

I am going to install (hopefully) my 1.6:1 roller rockers tomorrow, on a pair of heads that was designed with these parts in mind, but only because they are aftermarket heads

The engine is Buick 455 based, although bored 0.030" over. The heads are TA Performance aluminum Stage 1 Street Eleiminator pieces

The heads themselves have the old style Buick pedastals for the rocker arm shafts. TA sells roller rockers, however, and I have a set of those as well

For those unfamiliar with the stock Buick rocker setup, it's robust if you have the 1.55:1 rockers, slightly less reliable if you have the 1.6:1 (poor stampings, I'm told), and the stock system is nice because you never have to think about it, but not very good because you get what you get, you have no choice, no adjustments, ever

I'll be installing these tomorrow I hope, and I have heard a lot of talk about adjustable pushrods being needed for roller rockers and this and that, although the manufacturer, who is a Buick specialist, says that they may be necessary, it's not a definite thing. I'll soon find out!

I have the basic idea of the adjustment down. But what I don't understand quite yet is the preload in regards to "undesireably rocker geometry". OK, you turn the allen head screw, the cup on the rocker goes up and down, you simulate a ratio by the length you effectively make the rocker arm, you're changing the hypotenuse of the triangle formed, I get that.

But what is really happening with 'undesireble' geometry? My piston will be well over an inch in the hole when any valve's open with my cam, and the block didn't need to be decked before when I had the machinist prep the block, and it's never been worked on by anyone except the original assembly workers and myself, so I'm not worried about smacking a piston.

What I'm wondering about is: are you really changing the valve event timing that much by turning the cup screw in 0.050"? What's that roughly translate into in regards to timing? I know it matters from engine to engine, I mean just in general. It seems to me that when they caution about adjusting the rockers too much, it's kind of a blanket statement that makes the units OK to work with a block like mine, and ones that have been zero-decked, too

Thanks, Richard

Turns out I was worried about nothing. I think that the instructions and words of caution are so even guys with custom everything can use the same instructions I do.

I used the stock pushrods and set lash and then 0.050" preload, all the rockers got adjusted well within spec. I'm getting very anxious to try this engine out with all the upgrades...I just picked up my new 2000 rpm torque converter, too:) Maybe the engine *won't* blow up when I turn the key!