I bought my first rx7 series 3 (1985) model a few days ago. It is completely stock nothing has been modified or changed.

So with the engine temperature gauge (after the car gets warm) the needle only moves up by 2-3mm. Is that normal for them or should it go to the half way point when it's warm?

 

Personally I am not into 1st gen's but I will quickly add that I don't trust anything that was made in the 70's.That is why I divorced the wife...lol!
(replaced with a newer model that is more efficient..haha!)

I know that the Series 4 goes to 1/3,and the Series 5 goes to around Half though.

Diabolical1 is the 1st gen guy.Maybe he can chime in with some info.

 

I have seen then go up a quarter of the way or up a few mm like mine. I just drive the car around for a while and dee what is normal. If it goes higher than that point while idling or on really hard drives you know its in the red. Yuou could also verify that all connections on the sensor and dash harness are tight as there may be hidden corrosion in there. I saw one dash circuit sheet that was pretty badly corroded from moisture in the car, replaced it and gauges started reading as they should.

 

Normally on a first gen the temp needle only goes about a quarter of the way up. I would however recommend that you replace it with a real water temp gague as the first gen gagues are not known for their accuracy. Will the stockers work? Most of the time yes..but a good aftermarket gague is way more accurate.

 

about a quarter to a third of the way sounds right, when things are working right. if you have a clean, solid connection at the sender and the gauge is not moving around with normal driving, i wouldn't sweat it. that said, i have seen S3 cars where the gauge sits just under half and didn't move even when the car was being driven HARD.

so since the car is new to you, i would strongly suggest you perform regular maintenance and keep a vigilant eye. a real gauge is an option, but once you get to know the car, the stock gauge can be good enough to keep you out of ... ahem ... hot water. it's 4:37 AM - cut me some slack.