[quote=LATECH;1630908][QUOTE=hcompton;1630899] Zero decking the block will give you more cr increase than cutting the heads.
That is absolutely backwards. Most heads have a quench area in the chamber, milling an open chamber head verses decking would result in the same amount of CR change, with a poncho head, because it has a quench pad (even small) you gain more raise in CR thousanth per thousanth milling the head than decking the block.
Also, engines today wont run at 300 degrees in the cooling system.Damage will occur. Absolutely.
I like your enthusiasm here but stick to the facts.
And Cobalt is RARELY incorrect, if you have a valid point ..OK. As of yet I dont see that. Chill out.
A 4x head as quench pad? In the 113 form i dont think so.
And yes they will drove a truck this weekend with a hemi 2012 water was always over 290 and it was cold as piss outside. So yeah they will run over 300. This is how they are increasing mpg with modern engines. And this was a big truck v8 not a small four banger. You will see several more increases in operating temp over the next two years for the 2014 mpg increases the manufactures will be trying to reach.
In order to reach a decent cr he will probably need to do both. And decking the block is almost always preferrable to cutting the heads.
How is he right if you cut the block a good bit your intake still bolts up. Not true for heads. Then you need your intake milled as well. And .050 will do next to nothing on 455. Its not a 305. Even 350 heads need to be angle milled and all the bolt holes and flanges fixed. And that will usally only give you half a cr point.
Really depends on what engine he has. Trans am engine may be good. But passenger car engine will have very low compression if its late 70s.