alright guys, im almost done with this vortec build for my 383 stroker that im planning on putting in my 86 iroc z. now im super paranoid seeing as how this is my engine and its not a straight stock rebuild, and i used vortec heads which i know need some modifications to work.

stuff done so far:

new exhaust valve seats- moved up a size to 1.6 exhaust
cut intake valve seats - three angle
new valves
installed bronze valve guides
pocket ported
installed yellow zo6 valve springs with special retainers and umbrella valve seals


the cam in this engine has .487 int/.490 exh lift with 1.5/1 rocker ratio. i know that these springs are good to .550 lift. but now the more i look into these heads, they say that i might run into a problem running such high lift. suggesting i machine around the valve spring pockets to accomodate larger double valve springs, but i assumed i didnt need to do this because of the springs i went with.

now the other problem they say id run into is too much lift on those guydes. and i might actually to cut the tops to prevent the spring from bottoming out on the top of the guides.


oh and lastly. i still have pressed in rocker arm studs. i havent made the investment into drilled in studs and i was wondering if this was something absolutely necessary seeing as how this car wont see track time more than acouple months out of the year.

any help or tips?

 

i dont think you'll have a problem without screw in studs with stock/single springs but they are nice to have. the best thing to do is mock up the engine with solid lifters. check coil bind at max lift, need .060". i've never had a problem with valve guide clearance. it should be around .100"

 

You will need to check and see if you have the clearance from the valve spring retainer to valve guide at top cam lift. Looks like you might going with 487, if you clear guide by .060 the rest should be ok.