im planning on re grounding my 87 n/a fc base model. what should i ground and what should i re ground? and what gauge wire should i use?

 

4 gauge is fine. ground things like coils, strut tower, firewall, intake manifold, alternator, starter, block, ECU, etc.

 

Or just read aaroncake's website and be done with it.


aaroncake.net


Why would you ground the strut tower? Or the intake manifold? =O

 

Read this:

http://aaroncake.net/RX-7/grounding.htm

4GA is massive, crazy, pointless overkill. The entire electrical system can't crack 70-80A, so why would you need multiple cables capable of handling over 100A all over the engine bay?

Why would you "ground" the coils? They're bolted to and grounded through the chassis.
Why would you "ground" the intake manifold? No electrical components use it as a ground path.
Why would you "ground" the alternator? It's bolted to and grounded through the engine.
Why would you "ground" the starter? It already has a huge ground cable (that also serves the whole engine) that goes straight to the battery.

It sounds like you've been sucked in by the BS marketing of crap aftermarket car accessories.

 

The two I've found most useful:
Alternator frame to body at the fuse block mount.
Replace the cheezy clip on ground from the top of the bell housing to the firewall.

Those help keep spark & alternator noise away from ECU signalling.

 

No need to add more cables to the mix, just go over all of the factory grounds and redo them. When you get to the ECU ground, solder all wires together and this is one place to run a better ground to a point in the engine compartment.

Read Aaron's write up...

 

What's your basis for that claim?

 

You can test it next time you get the use of O-scope.
Clip your probe on the O2 sensor signal at the ECU & set the sweep to around 200-400 Hz.
Then pull off the firewall clip & watch the noise pick up.
If the clip is loose, just jiggle it & watch the noise.

I suspect there are very few RX-7's out there with the origonal exhaust system grounds.

A cheap replacement radio can wine with alternator noise.
The alternator-to-body ground will often fix it.

 

Since the alternator is already grounded through the engine, which is grounded directly to the engine, I bet making sure the factory ground points were in good condition would have the same effect.

 

on the MANY rx's i have worked on in the past 17 years here what i ground. Batt. to a clean paintless body mount, i ground both sides of the motor back to the body. I add 3 extra gounds to the ecm and ground them to the body.
The ecm grounds will help with 3800 rpm stumble. the batt. to body just adds a new fresh grounding setup to hep the old stock wiring out. the motor to body will help with small voltage issues and on my fb the motor/body ground helped out my alt. i saw a 1 volt increase on the stock cluster.
I use 8 ga. car audio wiring. I bought a 750 ft spool of mtx 8 ga off ebay and i still have TONS left. I also solder on the ringlugs to the wire and a little heat shrink makes then look great.