'84 automatic go fast mods
 

Working on a nice little automatic '84 with overdrive. For some reason Racing Beat has a different part number for the '84 auto exhaust systems. I don't know why. Anyone know?

No matter. You'll see why later in the thread.

For now, here is a description from a different thread (since I don't feel like retyping it all).

Passes emissions with flying colors. Has decent power for an automatic. Only about 10,000 miles on rebuild.

Was rebuilt in '03 with 184,000 on the clock (car now has 190something). Automatic trans meant engine only saw low RPM, and rotor housing wear was minimal.

We replaced the rotor housings with some brand new 12A turbo housings. Exhaust ports are a little bigger than US-spec. Still passes emissions though.

Car is NA with all stock emissions gear currently working as far as I know. The plan was to swap out the rat's nest and swap in a modified Nikki and exhaust for more power.

All the emissions gear was carefully removed and stored. I only broke two small bolts on the heat shield and exhaust manifold. I have a spare '84 manifold and heat shield in good condition so I'm good either way.

The engine was built with:

low mileage '81-'82 rotating assembly
'83-'85 side plates (with beehive coolant T fitting in rear plate)
J-spec 12A turbo rotor housings
new Mazda apex seals and various other seals and springs

The car is an '84 automatic with overdrive.
Black with fading clear coat. Still looks decent though.
Needs wiper rack replaced
needs power antenna and radio
Good brakes
tranny shifts fine

Moderators, the point of this thread was not to try to sell anything. Just to illustrate the project, and the motivation behind the mods.

The good is that it passed emissions, flawlessly. The bad is since it's an '84, with a sometimes intermittant trailing (tach dies then comes back after a few minutes) it tends to bog and run itself out of gas. Also the stock carb's accelerator pump is weak - probably part of the bog problem. Also the emissions devices are aging and don't work as transperantly as when new causing driveability gremlins, which on an automatic, cause it to stall requiring the driver to shift into N in order to restart it. Distracting and anoying.

With no plans to covert it to a stickshift, a different solution was required. One of enhanced driveability through carb mods. If I can get a stronger smoother idle, it will make the car much more pleasant to drive. And isn't that the point of an automatic? To just sit back and use one foot and one arm? Well maybe not exactly lol but it should be. :)

The only question I have yet to answer is what to do about the PCV system and the oil filler tube.

Now since I'm boring you I'll get to the pics.

Nice shot of the car.
https://www.rx7club.com/forum/attach...d=229305&stc=1

The stock engine bay.
https://www.rx7club.com/forum/attach...d=229306&stc=1

These came highlighted like this right out of the box, though not quite as dirty. :)
https://www.rx7club.com/forum/attach...d=229307&stc=1

Other side of the engine bay.
https://www.rx7club.com/forum/attach...d=229308&stc=1

After some removal work you can finally see the top of the engine. Notice the OMP injectors? Notice the undrilled coolant ports?
https://www.rx7club.com/forum/attach...d=229402&stc=1

After removal of the manfiold you can see something interesting. There are two emissions holes near the bottom studs. The only exhaust gasket we had was for a thermal reactor and as you can see, there was a small exhaust leak on the rear rotor. I had already cleaned off the carbon before this shot was taken but I'm sure you get the idea. No wonder it alway sounded like it had an exhaust leak. You could definitely hear when the flapper valve was doing its thing. :D
https://www.rx7club.com/forum/attach...d=229887&stc=1

A closer shot of the offending hole. Hey, notice the exhaust port size? That's stock! We didn't have to touch it. Pretty nice don't you think?
https://www.rx7club.com/forum/attach...d=229888&stc=1

Here's the custom exhaust which came off of an '83. It was a rusty mess so I spent some quality time with a wire brush and an alcohol soaked rag. Then some high temp paint and it looks better. Will it last against the rotary's hot breath? I don't care because it looks good right now. :)
https://www.rx7club.com/forum/attach...d=229889&stc=1

I was running out of time (and patience) so I did a quickie over the last part and didn't do the muffler itself. Of course I could always touch it up after it's on the car. No big deal. I don't even know how it's going to sound. As you can see it's a muffler shop special but hopefully it will outflow the stock stuff and not be too loud. It's certainly lighter than stock
https://www.rx7club.com/forum/attach...d=229890&stc=1

Nikki and mani mods are described here. https://www.rx7club.com/forum/showthread.php?t=637323

Carb
https://www.rx7club.com/forum/attach...d=229893&stc=1

manifold
https://www.rx7club.com/forum/attach...d=229894&stc=1

Header on engine and manifold. As I was short on time and battery power, I only got this shot and one of the exhaust tip.
https://www.rx7club.com/forum/attach...d=229895&stc=1

Exhaust tip. The wet spots are water. :)
https://www.rx7club.com/forum/attach...d=229896&stc=1

Well, that's as far as I got. I can't progress until I figure out how to run the PCV system to vent the oil tube. Since there is no PCV valve on an FB, I'm thinking I could hook it up similar to this thread. https://www.rx7club.com/forum/showth...1&page=1&pp=15

However I don't know what the purge valve is and I was wondering how bad it would be to hook the oil tube directly up to the carb spacer.

Which nipple should I use? I haven't decided whether to have vacuum advance or not yet.

how many cars/projects do you have!!?

You should see the ones I don't post. :)

Anyone have any ideas about the carb spacer?

I got it figured out. It runs nicely and is quicker than my white REPU. The trailing ignition controls the fuel pump relay and it's been going out so I need to look into it.

I looked into it. It turns out the trailing ignitor had an intermitant problem. I swapped in a know working one and the tach has been steady ever since. No more dead trailing ignition allowing the carb to run itself out of gas. :D

Jeff, take a look at wecycles thread further down about some trans mod kits that he found available.

Thanks for the heads up but this car is staying auto. I just did a final tune on the carb yesterday and it gets up and moves now. I only hope the two hose clamps on the upper radiator hose stop the dripping problem. If not it'll need a new hose.

https://www.rx7club.com/forum/attach...d=230698&stc=1

I freed up a stuck wiper rack and replaced the driver's window yesterday. Some knucklehead tinted it with purple tint that rippled and became a safety hazard.

His thread is on Automatics and shift kits and valve bodies that he found.

Oh you're right. Duh for me. :) I should have said this car is staying stock. My Cosmo is getting the manual treatment.

Jeff, why don't you go ahead and DLIDFIF this one o you can finlly say you've one yor mod on a 1st gen ? :icon_tup:

Then everybody would constantly bother me with questions.