Neep

Or maybe this isn't a basic question, which is why asking the question.

I've got an 85... something. Whoever owned it before me removed all the badging, so all I know is it's go the 12a in it. I've noticed that my 7's idle speed will increase as the car gets warm, going from mayb a stable 800 to 1100. This makes sense to me because as the engine warms up, it's not leaching as much of the energy from combustion to heat up the engine. However I've also noticed a drop in RPMs at idle when the voltage drops. There's about a 100 to 200 rpm drop. I'm not really sure why this happens. It has nothing to do with spark I would imagine. My only guess is that the alternator kicks on right away and that puts a little resistance into the equation? Mainly I'm seeing this when I turn on the headlights. Any idea why this happens?

christaylor

It's the "drag" on the system by the lights. With no lights on, the alternator isn't having to do much charging (aside from startup). When you turn the lights on, you're using ~50A(?) more than you were before, so the alternator's working harder.

At least, that's what I think.
I never did well in physics....

smnc

Anything that uses power will casue the alternator to work harder, causing a drag on the engine. The lights shouldn't use THAT much power, so make sure your alternator and battery are both good.

Also, the S or base models don't have model badging.
They did come stock with steel wheels, no moonroof/sunroof, and the analog radio with no equalizer (also no fade/balance joystick in the center console)

If this sounds like you, then you have the lightest, strongest RX-7 Chasis around

Neep

My RX-7 isn't just missing any model badging, it's missing all the badging with open holes where the badging should be. It doesn't say RX-7, or even Mazda anywhere on the car.

I am currious as to what level I've got though. I've got a glass moon roof, crank windows, power mirrors, Equilizer, cruise control, and AC. Any guesses?

Feds

Rear Disk Brakes?

drunkclever

I have a '85 with more holes than swiss cheese... only badge is in the front.. the newer mazda emblem. Its got hole that run just behind the doors.. all the way around to the other side.. I thought it was some type of mod that previous owners did but then a friend of mine told me that it was a targa top? what the heck is that?

edit:::>>>....

https://www.rx7club.com/showthread.p...ighlight=targa

thats a freaking awsome top..!

smnc

Rear discs make it a GSL, rear drums make it a GS.

smnc

Don'tyou wish it was a REAL targa like that?...
Hell, don't I wish, 'cause I've alwasy wanted to see one in person...

Anyways, it was likely a targa band. Do a search for that and you should find lotsa posts

peejay

The lights won't be drawing more than 10A, then again the alternator's output isn't all that much at idle, either.

10 amps is about 140 watts, or just under 1/4hp. That's a sizeable amount of the engine's output. Remember, when at idle, the engine is making just enough power to turn ITSELF at that speed, any additional load will drag the engine speed down.

It's neat to see how idle speed changes depending on oil pressure. After an oil change, on many cars, you can watch the idle speed drop 200-300rpm after the oil pump stops sucking air and builds pressure.

And people wonder why I am not in the "let's run a huge oil pump and super high pressure and the thickest sludge that can be poured from a bottle" camp.

OnlyOnThurs

Hmm this is my 82' GS!! I have no model badging anywhere...just the rx7 badges...no sun/moon roof.....no fade/bal. joystick......it came with steel wheels (which i am about to sell soon on here if anyone is intrested they will come with the center caps that say mazda...sorry for the plug), Drum rear brakes......the only thing i wish i had was disc rea breaks. oh well ill try to find an gsl rear end some day soon.