S30 Head Specs

During the 8 year run of the S30 chassis there were a few major engine changes made. First is the size change from 2393cc to 2565cc in 1974 and then in the US market the engine changed again to 2753cc. Here we will talk about the Block, Cylinder head, Crank and piston differences.

Head Differences

Head Identification

The L-series had six different heads used on the different blocks. Here we will be charting the differences between the heads and how to identify them.

To Identify these heads you can look at the head number that is casted into it between the 1st and 2nd spark plug holes.

Years and Models
Compression Ratio
Chamber CC
1970 240Z E31 Block
Uncommon, desirable head that came on many 1970 240's. It's chambers were high-quench designs, however the valves were smaller than the 260 and 280? heads.
1971-1973 240Z and 1974 260Z P30 Block
8.76:1 240Z
8.26:1 260Z Dished pistons
9.24:1 260Z flat top pistons
2 versions were available, a small valve on the 240Z and larger valve on the 260Z.?
1975-1976 280Z N42 Block
The larger valve N42 came on the 1975-76 280Z. 48 state U.S. 280Zs didn't use a catalytic converter until 1977, so the head came with softer brass valve seats for use with leaded gas. Many people like these for performance because of it's square exhaust ports. And as a easy mod, putting it on a flattop L28 motor puts compression in the mid 10's.
1978-1980 280Z Zx N42 Block
Has diamond-shaped exhaust ports with emission liners, which some feel reduce flow. Starting in 1977 Nissan heads came with steel seats for use with unleaded gas. Like the N42, putting it on a flattop L28 motor puts compression in the mid 10's.
1981-1983 280zx Non turbo F54 Block
Came on 81-83 flattop piston L28 (F54) blocks. It has a 53cc chamber and must be used with flattop pistons or compression drops to 7.8:1 (with dished pistons). The exhaust ports/liners are identical to the N47, and used an internally oiled cam.
1981-early 1983 280Zx Turbo F54 Block
It has the same combustion chambers as the P79, but has square exhaust ports like the N42. The P90 and P90a are said to be the best flowing heads due to their turbo origins. They both use an internally oiled cam.
Late 1983 280Zx Turbo F54 Block
Hydraulic lifter head, but many of the heads were in fact equipped with solid lifters. Usually these heads were models created earlier in the production year.