Maxpwer

iTrader: (7)

Long story short, I was rebuilding my engine a while back and found that my 91 Cali spec has "special" exhaust valves. These are distinguished by their markings ("EX S" instead of the standard "EF") and better flow (no "hump" on the valve, and smoother stem). Ive been trying to figure out what cars came with these valves. Every engine Ive torn down have had the "EF" exhaust valves. I suspect these valves might have come from another car, but the previous owner (who bought the car new) kept meticulous service records and there is no indication the engine was ever replaced or even opened so I believe these came from the factory. If you guys have any information, please share. Here are some pictures of the different valves....

whattingh

All I can tell is both is nissan original valve's(The little nissan logo). Maybe there was a short supply or something and they borrowed from one of the other vg siblings.
Just my thoughts

mikekantor

iTrader: (5)

The valves in the FSM diagrams look like the EX-S valves for the VE and the VG, although they arent necessarily accurate.

CapedCadaver

iTrader: (8)

to OP, probably the EX-S is a cali thing. Calis are rare.. check Courtesy to see if their part #s are different (the J30-0000xx style number not the xxxxx-85E00 number) between the two. It will show different once you get to the page with options/prices, IF they are different. I would look myself but can't at the moment.

internetautomar

iTrader: (30)

chances are the EX-S # has been superseded to the the EF # by now. it may have been different back in the day, but after years they stop keeping exact replacements and make them "usable"

Maxpwer

iTrader: (7)

I thought it might be a cali spec specific valve but only my 91 cali spec car had these EX S valves. My 89 cali spec has EF valves. Courtesy Nissan has only one part number for exhaust valves.

CapedCadaver

iTrader: (8)

are you equally sure to the originality of the engine on the 89? i tried the dealer and they cannot match an engine serial to a VIN.... at least the ones i asked couldn't.

Maxpwer

iTrader: (7)

Yes, my father bought the car new in late 88.

Wiking

I guess this is it: mfg at car plants was hectic supply chain manipulation still in those times, they had to use anything available not to shake production flow... On top of that, no records keeping - spare nightmare.