a few questions
 

so I just got my 88 rx7 rebuilt and it has s5 irons with s4 rotors and housings and I was just wondering how can i go about lowering my idle its idling at 2,000 rpms cold and 2300 rpms warm. Also how would I go about getting the air out of my coolant system? The radiator is full its not letting out any bubbles out of the filler(S5 radiator and waterpump housing so no bleeding screw) but after about an hour of driving it it starts getting to half gauge. Don't want to keep driving it once it hits half because we all know the stock gauges arent reliable. any tips will appreciated thanks.

just below half way up the gauge is normal for an S5.

Before the rebuild it ran quarter gauge just like an s4 motor and it was a complete s5 motor. and its getting to half not below half its getting to half gauge.

Does it get better at highway speed? Does the temp gauge climb at a stop light?

If it's idling at 2300rpm, I'd imagine so.

I have only had it upto 55 mph and then temp stayed about half gauge at 55 with heat on full blast stop lights it would raise lime 1mm or so not alot.

OK, this "half gauge" and "raised a mm" is a silly way to collect data.
Get a real temp gauge and stop guessing what your temps are.

Also, until your engine is running properly (i.e., NOT idling at 2300rpm), you temps are going to be weird anyway.

replace the thermostat with one that has a air bleed port, OEM type.

it's going to idle high until you bleed the cooling system properly, so ignore that for now.

cut the bottom out of a 2 L plastic soft drink bottle and place it in the rad fill point .. fill rad via the new funnel.. filling it up so it holds 1.5 or so litres above the rad
.. the extra head will overfill the rad but force some of the airlock out through the funnel

What do you mean air bleed on the thermo? Only type of air bleed I have seen on a fc is on the radiator. Am I mising an airbleed hole on the thermostat housing on the s5?

he means get an original thermostat with a jiggle pin hole , turn it till hole is at the top..

your main issue is the clash in rads and fill points and bleed points between the combination of 87/88/89 type parts has led to no genuine burp point at highest part of cooling system

use the plastic coke bottle to fill up ..massage the top hose .. do it all again after a drive

okay i will do that tomorrow morning and let you guys know the results. How much will it drop the idle once it is bled right?

getting hold of the idle speed will be a result of the running temp and having the tps calibration procedure correct ( using the set couple on a standard ecu ) .. timing calibration ( again set couple , warmed up ) .. and having no vacuum leaks

ps .. another trap for new players is that some parts ( aftermarket ) listings have the wrong thermostat listed for 89 and onwards FC's

if you have the s5 type thermostat neck ( 3 bolt,, no cap ) .. then you need to be using the thermostat specified in all listings for FD
( and the rubber seal gasket around its edge , which is sometimes an extra purchase )

if you have the s4 thermo in the s5 neck .. it doesnt sit right,, and doesnt seal off the bypass hole properly when warmed

I'm not new :P but I have a direct from mazda thermo for the car (S5) thermo but it was bought a year ago..

He has an '88, so his gauge may be an S4 one.

OP, is the TB stock, with a fast idle mechanism, thermowax and all?

Do you still have the BAC valve? You can loosen one of the coolant lines to it to get rid of air bubbles, I believe. Someone please confirm this.

Make sure the throttle cable has a little slack. Did you check that the throttle is closed? I'm also thinking vacuum leak and TPS adjustment off (as mentioned), but for the TPS adjustment it'll have to warm up and the throttle would have to be closed.

has stock tb i dont think it has the thermowax. It doesn't have the BAC its blocked off, Throttle cable has slack, Also with all my adjustment screws all the way down my tps is reading 2.3 volts but wide open reading 5.11. We did manage to get the volts down to 1.7 but thats all the farther we could get it down and it didn't effect the idle at all, But did find 3 vacuum leaks that got sealed up and it dropped the idle 300rpms..

TPS must read under 1 v for it to sense idle position .. it must see 1 V here,,be warmed up , revs dropped below 1000 rpm and set couple enabled to be able to set the timing calibration by moving the CAS base to 5 and 20 atdc