Noticed a port filled on tear down
 

So this might take a little back story but the quick question is, why is this port filled with epoxy or something?

Back story: I picked up this car after it had been sitting for 16 years because the previous owner couldn't get it to pass smog. Alas, I couldn't get it to pass either even after some tuning and other emissions maintenance so yesterday I took off the TR, intake, carb, etc. I found what you see in the picture and am genuinely confused. To me it looks like they took an engine from another car and so that the intake manifold would fit since it doesn't have that port, they plugged it. As I'm swapping the intake, exhaust, carb, etc from my parts car which does have this port (it's an fb), should I clear it out or what? Any help or theories are appreciated.

Thats an exhaust port for the ACV valve used for emissions crap. Early 12As (79/80) didn't have these or an intake that would cover it. So common practice is to either cover it somehow or seal it up with JB Weld or the like. Since you have an SA, I suspect someone swapped in this engine at some point.

I can say that the 1979/1980 intake does not cover that port entirely. The 1981-1985 intake does. I found this out with my 1979. All original engine/intake/carb/etc and that port does not get covered. It's exhaust so I'm not sure why it's open. It doesn't make sense to me. I had a 1980 and put an 1984 engine in it and I filled that port. I'm torn if I should fill it on my 1979.

Here is a pic of my 1979.

https://cimg9.ibsrv.net/gimg/www.rx7...76451a1c41.jpg

mmm...love those tall port engines. mine looks just like that but it's a 13b tho. is there a sensor in the top of that center housing?

Since I'm swapping intakes, would it be worth clearing out to help pass smog? Right now that's the only thing keeping the car off the road.

Just did some research on the different intakes and that extra port. It looks like the fb intake has a shorter intake port and the taller ones are a bit better for performance. Is this true? If those were to not match up I could see why that would be quite a problem. I'll check my other manifold when I get home today. No sensor by the way.

The early ports are better, bigger in the SAs.

The intake ports never really match the engine ports. The ports need to not match to provide a lip to reduce the reversion as the exhaust port closes duing the sweep into the intake port. Without this mismatch in ports, the car will not run well, especially at idle.

Cool info, both of my intakes have the same size ports so it wouldn't matter anyways. I confirmed the motor is a later year 12A so now I just have to decide between which carb/intake combo. I had the car running with the sa carb and such but if it would help emissions I might use the other set and clear out that epoxy. Would it hurt emissions much to block off the ACV set up and just run a line from the air pump to cat? The sa ACV wasn't working properly before so I'm not sure. The other carb has been rebuilt but it has a dead TPS and it's got a vacuum line that I can't figure out where it's supposed to go. Thoughts? Opinions? I'm trying to fix it this weekend so I'm hoping to avoid ordering parts.

that rectangular port is for the 81+ air injection system. the air pump air goes from the air pump -> Air Control Valve -> to this port -> to the exhaust ports. Mazda calls it 'Port Air"

the SA Thermal reactor system is different.

the 81+ cars will never ever ever pass smog without this air injection port working. engine in the pic is an 81-85

Well that was close. Yesterday I had just finished installing the new exhaust and put on the 81+ intake but I hadn't mounted the carb yet. Looks like I'll be taking it back off to drill it out. What's the best way to do that without getting a bunch of junk inside the engine? Drill holes and then knock it loose with a chissel? Good quotes BTW.

On a different note, the TPS sensor is frozen. Any ideas on how to get it unstuck and will the 81+ TPS work with the 80 ECU or do I need to fab a new mount for the 80 TPS?

Last question: The purge valve between the two cars is different. Since I'm keeping the rats nest for now, how should I run the tank and crank vent. On the fb they ran the two lines into each other but through the charcoal canister? Should I just do that or would a filter between the two lines work just as well? Thanks for all the help so far.

Theres a TPS on SAs? I don't recall that on any nikki.

Its more of a switch that a sensor. It's either on or off but it uses the same connector and is mounted in the same spot. I got the newer sensor to work so now it's just the question if the ECU will work with it. I've removed the intake and are ready to drill the filler out. Thoughts?

Keep a shop vac running so it pulls as many chunks out as possible as you drill. There is no telling how deep that material was stuffed into the hole. You might get lucky and get it all out though.

Unfortunately I wasn't lucky at all. It goes down farther than I can get with even a small drill bit and my tap. It's still completely plugged but there probably isn't much left. I gave up and right now I'm installing the carb (a float was stuck so I've got to fix that now). At this point I just want to know if it runs. Thanks for the advice so far. I'll keep this updated if I make any progress.

If the engine is out of the car, put it on an engine stand and turn it post down.You could also try drilling a series of holes along the outside edge and space them apart. Maybe it will come out mostly in one chunk.

EDIT: Too late, just read your last post about trying to get it out.

Thanks anyways for the idea. I'm thinking it'll need a rebuild to get the rest of it out.
I got everything installed and now the car fires up, runs rough for a few seconds and then dies. I've tried the mixture and throttle screw and they make no difference. I just finished puting the carb back together again so I'll give it another try. The float bowls have fuel and the floats are adjusted correctly. Anyone know what would cause something like this?

Fixed it. I'll explain how in a little bit

So let's just call it not having thought everything through... The reason the car would die consistently after being started was because of the shutter valve. Since the solenoids are open loop without power, the valve was getting vacuum as soon as the car started, thus killing the rear rotor and the car with it. The solenoid wasn't getting power since I'm still using the wire harness from the '80 and it didn't have that connector. I ended up putting a bind cap on it and it started up just fine. Right now I've got a lot of white smoke so that'll go on tomorrow's list along with trying to get it to idle a little lower. I've also since fixed the vents by picking up some hose and running them to the charcoal canister I stole from my parts car on the other side of the engine bay. The mystery vacuum line has also now been remedied along with flooding issues (a good knock with a wrench works quite well). Hoping it has a chance at passing smog even without that port. Thanks for all the help, if I find more issues (which of course I will), I'll update tomorrow.

Well it runs but there a noise on the passenger side of the engine bay that sounds like an exhaust leak but I can't find one. I wondered if the mismatch emissions systems could cause it but I've gone through and tested powering solenoids manually and nothing changes. Ideas? It kinda sounds like a plane.

The ACV port might, in fact, be passing some exhaust out into your engine bay now. Listen around the area where you were trying to remove the putty material to see if it gets louder there. It will sound like an exhaust leak.

The thing is that I'm using the 81+ intake manifold, which covers up that port. Thanks for the idea, but I think my exhaust gasket may be bad. I am however getting some water in the exhaust and I'm thinking it's from bad coolant seals in the intake. Once the car has cooled down I'll know for sure. I'm also still trying to figure out all the vacuum lines and decide what will still work with the older ECU. Right now I think the only things that match up are the relief and vacuum advance solenoids. The others I'll have to plug.

Here's a bunch of questions so get ready for the thought process... Ok, with the port-air port blocked off, should that affect at all how the car idles/runs? It should only affect emissions, yeah? As of now I'm having a lot of issues with the car idling rough and then it dying on decel. The only solenoids I have wired up (all of them are hooked up vacuum wise) are the relief and vacuum advance solenoids. When it does run it sounds like there's an exhaust leak or something else in sync with the exhaust pulses. The sound is coming from the middle of the passenger side of the engine bay, which sure narrows it down :). The car also is leaking water from somewhere near the intake/exhaust. I'm gonna say this is thanks to me having made a gasket from a role of gasket material I had lying around. It was a good and clean gasket, but I'm guessing the cutouts for the cooling jacket ports were too small so the rubber O-rings had the gasket between them and the intake, causing a leak since it's a paper gasket. I found an actual gasket for the intake sitting in one of my parts bins, so when I take everything apart tomorrow or some other time this week, I'll use that. If anyone's got an idea of why it's running rough (I'm betting on a vacuum issue), please put it on the table, I'm looking for anything that might get this thing to run. I've also done some research on the emissions system from the '82 car and it looks like I might be able to rig the two systems together (I'll be experimenting more later this week). I might try putting the '80 carb on the newer intake just to see if it'll idle smoother. If it ends up I do need the port air to be cleared out, I do have another engine sitting on my bench as a last resort, like honestly, last resort. I'd rather not pull the engine if it might work as is. Timing is something else that's messed up. I can get the timing to stay correct if I cap off the vacuum advance solenoid (it appears it's not getting any signal so the vacuum is going through), but since the other emissions system had the leading and trailing separated and this one doesn't, it now shows that the trailing advance valve on the distributor is seized. Yet another thing to be fixed. The car does run better though when it's hooked up and the leading is advanced if that points to any clues.

Sorry for the messy update, but I'm hoping stuff is clear enough to get some opinions out there.
Any help appreciated.

Just had an idea. Would it be possible to clear out that port through the exhaust? Where does the ACV port go, besides into the exhaust somewhere, obviously. I'm gonna have to take stuff apart anyways so if it's possible, I'd like to give it a try. Also, at idle, where is air supposed to be going? Port air or split air, or does it depend? Our smog test in Oregon is just an idle test so once the car is warmed up, should I send air to port air or split air to get the best emissions. I might just rig a toggle switch so I can control the switching solenoid from inside the car. Thoughts, opinions?

EDIT: Did some more research on cleaning out that port and it doesn't look like you can get to it through the exhaust. Any other ideas on how to clear it out? The tool would have to be a bent shape since it's now so far down that my chisel and drill can't make the 90 degree turn. I didn't get a chance to work on it today and probably wont tomorrow either, but Wednesday I'll have some time. Any ideas before then would be awesome since while the intake is off again, I may as well take another crack at it.

Anyone got some ideas? I'll be working on it when I get home today.

https://cimg1.ibsrv.net/gimg/www.rx7...401dd92c80.jpg


That center piece is iron, right? You could cutoff 4 to 6" of the the business end of a metal drain snake, put it in a drill and rip up the JB Weld? Go in with a wire wheel (like a chimney sweep but smaller) after that.
Maybe you could back pressurize the exhaust with your shop vac on blow into an exhaust port, then debris blows out of the hole rather than falling into it as you work. Might have to rotate the e shaft by hand until it lines up the right way.

This job sounds like no fun ;)

I would avoid heat. The JB Weld FAQ says the epoxy fails at 600°F and that sounds like it would cause warping.

Thanks for the idea, but for the time being I've given up on that port and instead I'm trying to get the car to run properly. If I'm correct, that port is just for emissions and shouldn't affect how the car runs. I did get some more of the plug out with some curved chisels I cut from aluminum plates, but it's still filled for the most part.

Right now I'm having problems with the car idling smoothly. It revs up and down and when it goes down, it sounds like it's about to die. If you keep your foot on the pedal it runs fine, it just won't idle. Spark is good and it ran fine before I swapped stuff so I'm thinking it's carburator or emissions related. I did manage to mount the other TPS on the carb, so now the ECU at least knows something. I've messed with mixture and idle speed with no luck. Any ideas?

EDIT: Did some more research on the idle problem and it sounds like clogged egr ports can cause problems. Yes I know that it's not an egr port, but perhaps since it related to emissions it could be causing something.... I'm honestly not sure, but if I can't the car running right I'll probably take another crack at it. I think the only method left to try is heat. How likely is it that the center iron will warp with that kind of heat?

I would not try heat. It can transfer into the housings and they are more likely to warping.before the irons.

Well shoot. That stuff is really down in there and is hard as rock. When I could get to it, even a chissel and a hammer had a tough time with it. A drill worked ok but there's no way to get one down that far. Any other ideas?

Edit: I once read an electrical blog where a guy took wire from a coat hanger, sharpened one end and used it like a small flexible drill bit. That might be a tedious but low risk way to chew it up/weaken it. Multiple holes, then back to the hammer.
----------------------------
One forum said that isopropyl alcohol would, over time, soften the JB. I can't confirm or deny, but you could pour a bunch in there and let it steep. Maybe do a test on some scraps you've already removed.

Soaking heat is not a good option for the reason's KC mentioned... coolant above 200°F is a worry and the fail temp according to the JB FAQ is 600°F for the standard stuff. Also, I guess there's an "Extreme Heat" version of JB that is grey when cured and theoretically withstands 2400°F. Who knows what's in your port.

Maybe a right angle chisel (https://www.summitracing.com/parts/skg-20016) and a big effing hammer? Maybe a right angle oscillating tool blade (Imperial Right Angle Plunge Cutting Oscillating Multi-Tool Blade) ?

https://cimg1.ibsrv.net/gimg/www.rx7...1644cac20a.jpg -- OR -- https://cimg5.ibsrv.net/gimg/www.rx7...be717fd2e1.jpg

Again, cool ideas and thanks for the determination on getting this fixed. Ironically I've already tried something similar to the coat hanger idea. I have some finding wires (like the kind for drilling through floors and stuff), but all it did was fly around so... Good thought though, and maybe since a coat hanger is a heavier metal it would work better. As for the alcohol, well... I've tried acetone but I've gotten enough of the plug out that it just slowly leaks into the engine so I can't really soak it and let it sit. I think a right angle chisel might be my only option left. I'll probably stop by home Depot later today and see if they have a chisel that will work.

Just a thought, what about dry ice to shock it?

Maybe not dry ice, but I've heard of some people having success with canned air (like electronics cleaner). It's apparently cold enough to do something to the jb weld. If the chisels don't work, I'll give that a try.

EDIT: Is it remotely possible that the partially opened avc port would cause an uncorrectable rough engine idle? It's the only thing that has changed since I last ran the car and now it won't idle well. By partially open I mean barely open. Just wondering.

Finally got the plug out of that port. I spent about three hours strait just on the port this weekend. I ended up just using a bunch of bent nails (I'll post a picture later), and a cheap chisel from Harbor Freight. The plug went down into the port about 3-4 inches so getting it all out of that little opening was no small job. The majority of the plug came out with some slow chipping but near the end, I knocked it loose and it fell down the port. The shop vac fixed that by sucking it back up the top where I then put a right-angle nail in underneath it so it couldn't fall down again, and then proceeded to break it up with another nail. When it all done I fed a finding wire down to make sure it was clear and it was so... back together it went. While I had the carb off I re-soldered the wires for the ECU temp sensor (which had fallen off), so now the auto choke works again. The car runs, but only with throttle and above 1500 rpm. Anything below 1500 rpm something switches and the car just dies. I've got a feeling the emissions system is messing with it because the TPS closes around there, not being adjusted yet. I ran out of time before it started to snow so I haven't done anything except for start it up that once. Once the weather clears up, I'll try to figure out what's up with the idle.

That's some persistence, good job man. These things are awesome for seeing into tight spaces...$22 and a laptop

I want to make sure I understand what you have. You have a 1979/1980 engine and using a 1981-1985 intake/carb? What year emission and ECU, if any, are you running?

Yeah it's a bit Frankensteined. When I got the car it had the 81-85 engine, with the exhaust, intake, everything, including the ECU, from a 79-80 car. When I swapped the intake, exhaust, carb, and emission solenoid rack to the 81-85 system, I also took the TPS from the previous year carb so that the ECU would still understand the signal. As for the emissions rack, the only stuff that matches up is the vacuum advance and the relief solenoid. I blocked and plugged the shutter valve, and the switching valve is hooked up but the early year ECU's don't have a wire for it.

So just to clarify:
Intake, exhaust, engine, carb, air box, emissions rack (81-85.
ECU, TPS, wire harness (79-80)

All vacuum lines are connected except for the vacuum advance (plugged because one actuator on the distributor is kaput) and the shutter solenoid. The switching valve is hooked up but there is no electrical connector for it.

Hope that helps, if something is confusing or missing just let me know and I'll update it.

Small update:
It stopped raining for a little so I had enough time to do some tuning. The car now idles at 750ish rpm but I had to richen the mixture quite a bit. The mixture screw is probably 5-7 turns from closed. The car definitely smells rich, but no smoke. If I turn the mixture screw clockwise more than where it's at now, it starts hunting and then dies. As of now I don't think there are any vacuum leaks, so would something emissions related be causing the overly rich mixture? Thoughts? I wouldn't care too much about the slightly rich AF ratio but I've got to pass smog. Its begun to snow again, so the next time I'll be able to work on it will probably be later this week.

You may need to get an FB ECU to make this all work. I assume the FB exhaust has cats? The other option is to understand what the sniff for and get some tools measure it or access to tools and tune until it passes.

Oddly enough I have the entire wire harness, ECU included, from my FB parts car. I was trying to avoid swapping them since the whole harness is different, and that would require the dash to be removed, tail-lights modified, etc. I might still do it this summer but I was trying to keep the SA more or less an SA except for the engine where I didn't have an option. What part of the emissions system would be most affecting the idle mixture? Since the SA ECU and system is a bit simpler than the FB, I had thought I could make a "stand alone" just for the emissions from an Arduino or something. I would keep the original ECU and keep the sensors wired to it so that other stuff will still work, but the solenoids would be controlled by the Arduino using the og ECU for input. I would need to do some research to find all the operating conditions but if I can't just manually control the switching valve, it might worth a shot.

This is my current emissions set up:
Vacuum Advance: In the name. Harness present. (normally open or closed?)
Relief Valve: Switches air from air pump to air box when rpm exceeds about 1000 rpm (dependant on TPS). Harness present.
No AC installed
Shutter Valve: Closes rear rotor primary intake port durring decel to prevent backfiring (not nesisarily needed and at the moment is disconnected) no harness plug.
Switching Valve: Directs air from air pump to either ACV port on engine (port air) or CAT air line (split air). (Conditions?) No harness plug.

Snow let up again so I may be able to do some work today.

Edit: One other odd thing. If you mash the gas from idle, it bogs badly. The accelerator pump works but may be miss-adjusted. Anything else that would cause this? I haven't messed with the AP much yet so that's probably what it is but just in case.

I'm not sure you can make the 1981/1985 rats nest (which have variation themselves) work with the 1979-1980 ECU and wiring. The 1979 has 3 to 4 square vacuum pots. One is on the carb and then there are 2/3 on the rats nest depending if it was cali equipped.

I'd be more inclined to swap to the 1985 engine harness/ecu and then work out what would be needed to make the 1980/1979 dash work (idiot lights and gauges)

As for the 81-85 rats nest I know what you mean, I've got at least three variations in my parts bin. My SA carb had two solenoids on it (vent, and decel), and three on the rack (advance, relief, and AC). The main reason I think combining the two systems will work, at least for now, is because this variation FB rack has only one vacuum advance solenoid as opposed to two like most others I've seen. The SA system used a line from the carb to adjust (leading or trailing, I forget which), and the other from the solenoid. The newer rack has both on the one solenoid and as I have one connector for it (as long as opp conditions are the same), it should work. The only other emissions differences is the shutter valve (not necessary), and the switching valve which could be rigged up for manual operation pretty easily. The carb I'm using doesn't have a power/richer solenoid and I've swapped the TPS so the signal matches the ECU. In other words, nothing on the carb is left unplugged. All I need to figure out now is if the ACV is even working and if it is, where is it sending air. If it's going to the wrong place maybe it'll fix the rich idle problem. If there's nothing wrong, I'll start messing with the other emissions stuff. Maybe this summer I'll swap the harness, but for now I'm just looking to get the car smogged and registered. I'll update if I discover anything new.

Did some testing last night and it appears the ACV is not working at all. Basically I jumped the vacuum lines for emissions stuff across the solenoids so they couldn't be a factor. No matter what I did, air always came out of the relief air hose. I'm guessing it's just locked up after not being used for so long, but when I go through it tonight I'll also check on the vacuum passages to make sure they're not clogged. What's the best way to break the valves loose if they are stuck? Sure hoping it's not a diagram that's bad.

Well darn... The relief valve diaphragm is shot. They were both frozen but only the diaphragm on the relief valve is bad, although I did get both moving freely. Unfortunately, that valve is needed otherwise air will never get past it and to the switching valve. Any ideas on where to get one?

EDIT: Just had a thought. Would it be plausible to try and seal it up? Maybe silicone or something else? Probably not a good idea but maybe worth a shot?

So using silicone on the valve seems to have worked. I let it cure overnight and I installed it this morning. It does the job ok, although air still comes out the relief valve when it's activated, but it's notably less air than when it's off.

Now I'm having issues with the idle dropping after you let off the gas and then slowly coming back up to where it's supposed to be. Sometimes it's enough of a drop to kill the engine. To be clear, I was having the idle issues before, now it's just higher on the priorities list. Ideas?

Edit: The idle usually only drops if the engine was brought above 2500 rpm. If the engine was around 3000-4000 or higher, the engine idle drops and stays low while also running rough and typically dying. What's odd is that if the car starts running low and rough (after decelerating), simply shutting it off and starting if back up fixes the problem. It even starts without a hitch. I'm just having trouble figuring out what could be causing this. I'm open to any ideas, even the outlandish ones.

New developments.
1. There was a t-fitting in the vacuum system that had broken (now replaced)
2. Float levels are a bit high (not fixed yet)
3. The check ball in the accelerator pump outlet may be missing (not sure yet)

Tonight I'm going to go through the carb with a fine tooth comb. Everything is coming apart and will be cleaned careful. The last time I took the carb completely apart was in the summer when I took it off the parts car.

Here the odd thing, the car would idle just fine once it's warmed up but if you touch the throttle (either floor it for a second or go above 2500 rpm), the car no longer idles. Turning off the engine and restarting it fixes the problem completely. Is there something vacuum related that could be getting stuck?