Ive heard many misconceptions on roller lifters, guideplates, alot of valvetrain crap. I just got a few questions about em if anyone knows.

I got a 383 shortblock (forged rods/pistons, cast steel crank), and I can get a good deal on some used Vortec heads (less than 1000 miles). Im usin the comp xe274h, flat tappet cam. I know that the vortecs use self aligning rockers, and if I dont use self aligning rockers I need to use guideplates. But what kind of power/throttle response can I see with using roller lifters? Im stayin 1.5RR since Im usin vortecs.

And one question about heads. Whats an acceptable clearance between the ID if the valve spring and the OD of the valve seat? I think I can use the springs that came with the cam kit without having to modify my Vortecs. I might have to grind down the valve guide boss down a little since Ill be pushin about .490 lift. Any input from the DIY'ers? Im trying to avoid the machine shop, and I know that they make cutters for the vortecs, but I cant find the right ones for my springs, #981 from Comp.

 

doubt you see any differance in response between a roller cam and flat cam given equal specs. there is no issues or spec with clearance between the spring and valve seat. are you sure that's the question you want to ask? use a vertical mill to reduce the guide height. it only cost me 2 dollars each to get the od of the guide cut down or spring seat increased.

 

I'm using the GM fast burn aluminum heads (vortec style) with the stock valves & springs on my 388 TPI with hydraulic lifters, non-roller XE262H cam, and self-aligning aluminum 1.5 roller rockers. No problems.

I don't have any way of comparing the power/throttle response.