Can I swap an E-88 head onto an engine that now has an E-31 head ? What are the differences besides the cc volumes ? I know this has been covered before but I had no success in getting into the archives. Thanks, Darrell 240Z

Yes to question #1. Question #2 E-31 has 42.5 cc combustion chambers....E88 has 44.7cc combustion chambers. E88 up to 7-73 has the same size valves, then the exhaust valve size was increased to 1.38 inches vs 1.30 inches on E88's before 7-73. The intake valves on both the E31 and E88 were 1.65 inches.

Edited September 30, 201014 yr by Diseazd

Is there no issue with using the larger valve on an L24 block? Can't recall for sure.

Regardless, you'll get a slight drop in compression, probably not enough to notice if you're just driving around, might be noticeable at a drag strip or a race track.

The early E88 is obviously no problem.....if using the later head with the larger exhaust valve, you should probably eyebrow the block for added clearance and flow if the block isn't overbored. The late 73's have the same bore size as the early Z's ......... not sure if they are eyebrowed from the factory for the larger exhaust valve.

The L26 blocks have the same bore as the L24. The L26 blocks are eyebrowed from the factory. No problem if you have a 0.5mm overbore or larger..

FWIW

Carl B.

Eyebrowing the block is REALLY easy if you have a die grinder and can be done with the head off of the engine if needed. There is a write up in How to Modify Your Nissan/Datsun OHC Engine by Honsowetz.