Yeah, it seems there are a lot of things that are "hit & miss" on theses cars. Nissan seems to have mixed parts over quite a time frame as they transitioned from one spec to another.

I have an (1971) E31 stashed away, I should look to see what valve seats it has. Engine was pulled by me at 70K miles in 1979 and buried in the back corner of the garage.

Kmack good call that is a vary good site. A real keeper It should be added to the tec files. Is that possable ? Or is it concidered someones property ? This one and the one on engines , there is so much good infromation in there.

It belongs to someone else.

Back before the "great website meltdown" we had a "links" section and many sites including the one kmack refered to were listed in that area. maybe Mike can put that section back up?

On my E31, it orignally had bronze intake seats, hardened steel exhaust valve seats. I also have 1 early E88 and 3 late E88's all with bronze intake seats and hardened steel exhaust seats.

Taking a look at the website mentioned, I think there is room for expansion on the E88 heads, In addition to large and small valved E88's there are also high and low compression E88's. So based on the heads I own, combined with the info on that web site and others, I'd surmise that there are at least 3 different varieties of the E88:

High compression, small valve

Low compression, small valve

Low compression, large valve.

I can only speak for myself but my Z only seems to like Amoco - Now known as BP.

If I use any other type of gas there is always a noticeable performance difference. Shell Gas being the worst.