Hey guys I have an 84' 351W block stock pistons gt-40 Y303 heads and cobra 1.72 roller rockers...Now what springs do I need for these heads ? also is there a certain valve I have to use? I know its 1.94 intake 1.60 exhaust anyone have part numbers for all this?
your cam of choice is going to dictate what spring to use, as in installed height, seat pressure, open pressure etc. As for valves you can run a standard length 11/32nds valve and more than likely a .530 viton valve seal
I had a set of Y's, and IMO, don't waste on dime on them if they are going on a 351. If the cam is a stock one, just use the heads "as is" and then sell them when you get more radical.
I spent $410 on headwork on those heads, and that was milling, valve job, bowl cleanup, and spring seats. NOT worth the money on such a big engine.
Remember, these heads are now only $699 new per set, and are ok for a 302 (not great though).
You car will likely make low hp, and very high torque.
So just make due for now, and buy some CNC wedges or afr 185's when you have more money.