I have not seen Tlowes dyno tests, but was there a test w/the boss removed, lumps installed & stock sized valves? Results? I would think not much of any gain w/stock valves. Anyone?
Snowman, the stock rocker arms can only go so far with lift, anymore lift needed, you would have to grind/clearance the slots in your rocker arms, hardly done anymore, since there are many rocker arm companies that you can buy from.
Roller rockers can help make your valve guides last longer, (less wear) Our valve guides are short in our siamese heads, & w/the 1.75 ratio, it is harder on guides also, so they wear quickly as compared to other cyl heads w/longer guides & smaller ratio rocker arms. Roller rocker arms will not cause your valve stem tips to wear & mushroom either.
I forgot @ what point in lift the stock rocker arms start to hit the rocker arm stud? Anyone???
For a street car, you do not need to go with that much lift, .550" lift is the most I would go with as far as lift is concerned. Heck, .510" lift is fine.
Just remember snowman, all the hp & torque is made through your cyl head, you get a much better performing engine w/a well prepped cyl head, if you do not do much of anything done to your cyl head,,, don't expect much out of your engine then.
If you just cut out your boss & do nothing else, you most likely will not see any gain & would not loose too much response because you still would have the small 1.72" intake valve.
Snowman,,,, Changing out your camshaft to a better suited turbo camshaft will give you more of a gain in power than if you were to cut out the boss, install lumps, & keep your stock sized intake valves.
