6.2 heads on 6.5 block

[Tileman]

I have bought 6.2 heads to replace my 6.5 cracked ones. The casting # is the same but of course the injectors are tilted a little. I noticed this morning that the pre-combustion chamber (the round circle above the valves) seem smaller or not oblong as the ones in my 6.5 heads. Do I need to try to change these or can I change these. Will it make a difference to anything if I do. Thanks a million. Cass

[HJacobson]

Smaller pre-cups might give you a little more fuel economy.

Other than that, I would leave the pre-cups alone and install them as they are. I don't think you will notice any change.