Checking for warped heads and decks

Question:

I just bought a 350 V-8 and want to replace the head and intake gaskets, etc. Friends told me that you need to have the heads shaved when you take them off. They said that heads warp, and you need to get them straight before putting them back on. Is this true?

Answer:

A Sometimes if they are warped, you need to have the heads or decks (mating surfaces on the block) planed flat when you remove the heads, but usually this isn’t necessary.

To determine whether the heads are warped, remove the heads and clean them of debris and carbon, then with a machinist’s straightedge placed on edge, check the heads for flatness. Shine a light from behind the straightedge and look

Chances are the heads on your engine are fine, but when you have them off, check them as well as the mating surface on the block for warping using a machinist’s metal straightedge and a feeler gauge. for gaps. Place your straightedge along the length, then diagonally, and check in several places along each head and deck.

If you spot a gap, measure it with a flat feeler gauge. If the gap between the straightedge and the head is greater than .004" for a V-8 or more than .006" for an inline six, you will need to have the head(s) or decks milled.