I am going to put LG4 heads on a 1967 Chevy 283 block. With the 283 block having a 3.875+30 over bore which is bigger than the 3.736 305 bore, what is the biggest valve I can use and still clear the bore with a large .500+ cam and 1.6 rockers? could I clear with 2.02in/1.60ex?

 

There's a difference between what you can do and what will do any good.

1.94"/1.60" is all that will make a difference. With a 283, 1.84"/1.50" would be fine.

 

I have 2.02 1.60 valves on 416 5.0L heads, but I have some custom combustion chamber work in there. If you do decide on big valves, you'll need to clear the valve area of shrouding, or you'll get some pretty ineffective swirl.

 

Yeah, but it appears your running this combo on a 350 block, unfortunately I dont have a 4.000+ bore to work with.

 

You won't hit the bores. Mock it up and find out, but i'm pretty sure even with .500" lift you won't be able to get it to hit the bore.

 

You won't hit the bores with 2.02/1.60 valves on a 305.

Still doesn't make it worthwhile.