307 heads on a 30 over 350 block

[mstudman]

I'm thinking of putting the stock iron heads from my '69 Nova's destroyed 307 on the new 350 replacement block. The new 350 block will be .030 over. Will the combustions chambers on the old 307 heads need to be re-worked to match the bigger diameter 350 30over cylinders? I already figured the heads will need to get redone anyway with new everything and probable have the deck surface machined flat.

[tazz3]

that would not work. the 307 head are smaller and they will kill the 350
well the diamter will be the same but the 307 head are not high perforemce

[dracer398]

The heads will work, but as Taz said your performance will suffer. The 350 heads had larger intake valves.

[wheelerew]

HI,

The 307 heads will bolt up to a 350 block, the problem is the bores are not the same. a 350 has a 4.0" bore while a 307 has a 3.8" bore (the same as a 283"). The 307 heads would actually be hanging over the piston instead of lining up with the cylinder. 307's were never designed for performance so instead I would spend my money on a good set of 350 heads. Also all 350 heads do not have the large valves. Some have the same size valves as a 307. If your looking for the large valve head, measure the diameter of the intake valve and it should be 2.02", if not then it's a head off a grocery getter and pass on it.

Hope this helps.