Cylinder Head Info ..

Cylinder Head Info ..

The 53 322 heads and pistons are all by themselves, nothing can be upgraded, it was a bad design, best to use the 54-55-56 heads and pistons (re-balance a must). Many 53’s were upgraded that way in the 50’s by the dealers.
The 54-55-56 heads all have the same castings but different machining and or valve sizes. Casting #’s do not tell you much. The 264 and 322 share the same heads in the same years.. If you have a 54 264-322 always use the larger 55-56 exhaust valves. If you have a 54-55 322 it is easy to make them into 56 heads with 15 minutes and die grinder, we can supply template with valve purchase from us. The 56 heads were designed for the 322 4″ bore so these mods should NEVER be used on the smaller bore 264 (except the larger exhaust valves).
The push rod holes in the 53-54 and early 55 heads are very small so when upgrading to new tube type push rods enlarge those holes to 15/32 for clearance. The mid 55 and later have the larger holes.
The 57-58 364 heads are the same as later heads except for smaller exhaust valve heads and shorter valve spring installed height.. One other thing, the coolant sender hole is different size and thread type.
All 59-66 364-401-425 heads are the same except the 66 California ones that had A.I.R. holes in the exhaust ports for smog equipment.
NEVER machine your heads for larger or taller valve springs, it puts the spring into the push rod hole it will chew up your push rods !
Always check for piston to head clearance, some of the new pistons will hit the combustion chamber with the piston dome top corners opposite the valve reliefs. At best it will knock a little, at worst it will shatter the piston!
Read the 15 most Common Mistakes and Boring limits and Upgrades for other head and valve info. If you have the 56-59 GM Torque Master you basically have a 56 Special 322 engine with lots of HD parts including a roller timing chain.. We have a few nos chains left but no sprockets.