Whats the max lift that a stock headed Lb9 can take, without the valves hitting the cylinder walls? Would a .510 w/ 1.6 rr's be too much?

 

I think that is way to much lift even without the 1.6 roller tip rockers. You really dont wanto to go over a .480 lift with the stock springs anything over that you start having problems with springs binding and valve float at higher rpms. Look for a cam with a little more duration instead of a huge lift. Atleast this what I have been told if you really want that kind of lift look for springs that will accomadate around a .550 lift I know that enginekits.com has elgins for like cheap. On a 305 that sought of lift is not necessary unless you have some really high flowing heads or have ported and polished your stock heads. No nee to worry about the valves hitting the cylinder wall It is piston valve clearnce might but I doubt it be an issue for you. The only time a valve will hit the cylinder wall is when something catastrophic happens like valve and piston interference. Oh yeah the zz4 cam has an exhaust lift of .510 I think if you keep the computer you would atleast need a custom chip. I would personaly look into something like the Ram Jet cam for a 305 with 1.6 rollertip rockers It would give you a lift not to exceed .480 its a milder cam that would work great with your stock computer. I do know where you can get a Ram Jet cam for like $200.00 e-mail me if you are interested.

 

anything over .460 or so you start needing to get rid of the pull out studs, enlarge the spring seats, and look at valve guide interferance, and i've never saw a problem with valve interferance untill you're over .625, but you should always dummy it up and check to make sure.

 

Oh the springs, retainers aqnd such would not be stock. Ive just heard some horror stories about too much lift and the valves binding against the cylinder walls.
Thanks guys!