The dude has a quick question for you guys. I'min the early stages of putting a new big block together and I was wondering if I am going to have valve to piston clearance issues. I am running a set of stock #781 heads, and as far as I can tell, the have never been milled. I am having them cut for the bigger valves though. The pistons that I have are TRW-L2465 (.215 domes). I am also going to run a Lunati 402A3LUN cam (.586 / .600 lift). I was just wondering if anybody else was running a similar combo and if they had clearance problems.. Thanks Guys!

Mark, I have 049 heads with the big valves, they are milled to 115cc chambers. I have TRWL2349 pistons, .210 dome. Cam lift is .595/.609...I have no clearance problems. I honestly dont remember right now the exact clearance, it wasnt a whole lot, but enough. Hope this helps. John

Use Long Slot Rockers or youll be building a new engine soon...

Godsend, I guess I don't understand... What's the deal with the long slot rockers??

To give you extra Clearence to Stud bolt. Otherwise your cam will melt down...

Mark, my clearances with a similarly sized SRP slug, same cam ( at 0 lash) and OC heads milled to 112cc,WITH the cam in RETARDED ( I didnt recheck after the cam was phased right) was .85 exhaust and .160 intake WITHOUT the .039" gasket I use. The tight exhasut clearance was my first clue the cam was in backwards ( -6 instead of +6)

You SHOULD be fine, but invest in some modeling clay and check it.

And as said before, whenever you start runninng near .600 lift ( OK .580 net), you better check everything in the valvetrain, INCLUDING pushrod length. I could actually use pushrods .030" shorter.

I am running 781's that have been shaved about .010 with the same pistons and same CAM. You will be fine use the appropriate rockers and make sure the retainers have enough clearance to the valve seal. In other words, the guides will need to be cut down when you have the valve work done. If you don't - take a lok at my home page and you'll see what it can do.

I also ended up using +.050 locks on my retainers to get my spring installed height correct.

Troy.

Who makes some of the appropriate long slot rockers? I was planning on using Harland Sharp roller rockers, will these work?

Mark
roller rockers don't have the slot just stock type rockers so you will be fine in the rocker department
What was being referred to is the slot the stud goes through in stock rockers.
If the slot is not long enough with a hi lift cam you will run out of slot & the rocker will hit the stud.