There are two types of 1600 cylinder heads, as far as valve seals go. All SAE aluminum heads are the early type on the left. The metric heads without air injection ports can be either type. The metric heads with air injection ports all use the late style valve seal area shown on the right. NOTE: The guides look different but are just different production batches, any head could have either type, and this has no bearing on the seal situation. IRON HEAD NOTE: Although the iron 1600 heads I've seen have guides in them, supposedly some real early 1600 iron heads were reworked 1500 heads. The 1500 iron head "looks" like it has guides but if you look closely you can see the upward projection that holds the valve is all one piece, and not separate with a wire retainer as shown below. And if it does NOT have separate valve guides (which measure .563 in diameter) you'll have to measure the upward projection that the valve goes into. If it measures .580 (like the 1500) you'll have to turn down these projections to about .563 to get the #132-32 valve seal to fit over it. The valve seals have to be pushed on with a little force, but you should be able to do it with your hands or a GENTLE tap.
Early type 1600 head on left has a 1" diameter raised platform for the seal to sit on. Seal (shown below) has 1" base. Valve spring does NOT sit on seal.
Late type 1600 head on right has 1 1/2" diameter "pocket" for valve seal to sit in. Valve Spring sits on valve seal housing (shown below).
Don't be alarmed that the valve guides look different, one picture shows an exhaust valve guide and the other picture shows an intake valve guide
Part
Number 132-32
Early Type
Part
Number 132-33
Late Type
These two seals have been mixed up on engines for the last 35 years. Using the wrong seal alters the valve spring base location which alters the spring compression. Although Nissan came out with the seal on the left in 1965 to try to correct the problems with the 1500, these seals were never included in factory engine gasket sets or valve grind sets. Aftermarket manufacturers copied the factory kit so the correct seals were left out of those kits as well. What WAS included was the simple slip-over-the-valve o-rings that were all that the 1500 had. Although these simple o-rings provide some benefit, it isn't much as the o-ring tends to ride up on the valve stem and not as effectively reduce the oil going down between the guide and the valve as a "modern" seal. The real seals shown above fit snugly over the guide, and in the case of the later heads, even the spring holds the seal down.
