I know this has been covered before and I've dug for answers, but can someone take a pic of their 1979/1980 engine with factory intake on? What I'm curious about is the port in the center iron.

I'm putting everything back on my early build 1979 and the intake does not cover that port. I know my engine and intake are the ones that came with the car new. I'll post pics of mine tomorrow.

 

I have my engine apart on the bench right now, but I set the intake on the studs to show you.
Mine doesn't cover either. That port goes down and over through the rotor housings and into the oilpan.
It seems like it should be covered, but it looks as if it is just open to the atmosphere?

 

Thanks - I didn't know it went to the oil pan. I thought it was exhaust. Glad to know it's not suppose to be covered.

Here is mine.

 

Correct me if I'm wrong but that rectangular hole in the center iron is for the ACV port from an 81-85 12a? I could be wrong though.

 

I was able to take some REPU irons and housing I just received a couple of weeks ago and validate that it is indeed open to exhaust. The center iron opening goes down and connects to the exhaust ports in the housings. There are a couple of long tubes/bolts that have holes in them. This allows exhaust to come out of the center iron square hole.

The part that puzzles me is that the factory 1979 intake does not cover this hole. It cover about 1/2 or less of it. I do not want to put any type of JB weld in it if this is the way the factory did it.

 

Ask Jeff20b what to do, he'll know. If it was me I'd probably stuff it full of jb weld and call it a day... Either that or say (d)uck it with that intake and ship it over my way lol

 

I fished a string through that port on my 1979 12a, and it doesn't go to the exhaust or the oilpan, It looks like it is not used for anything on this model. The entire passageway is clean with no oil or exhaust soot. I am going to leave this port as is when I reassemble this engine.

 

Tim - Can you look to see if the small exhaust port has a path to where your string runs through?

 

It doesn't go to the exhaust on the one I'm working on, your engine is together, for curiosity, you could blow compressed air in that rectangular port and see if it comes out anywhere,

 

I will do the air test tonight.

In any event, I think we have proven that what we see/have are factory setups and that port is not suppose to be blocked. I've never had this engine running so I can't speak to how loud it might be from that port.

 

It is supposed to be blocked. I'll see if I can find some pictures of the issue I had..

 

GSL-SE or S4 manifold on S5 NA keg



GSL-SE or S4 manifold on top, S5 manifold on bottom

S5 intake on S5 keg

 

The engine was literally shooting exhaust out sideways at the engine bay from that port. That is where exhaust is fed into the lower intake manifold. On the earlier engines it was fed from the sides in the front and rear irons, on S5's it was fed from the center iron.

 

I just went out to the barn and tested with air. I could not detect any air coming from the exhaust when putting ait in the square port. The hold in the small round exhaust port is so small I'm not sure if I could detect air anyway.

I've got some Mazda training manuals. I'm going to scour through them to see if this port is mentioned.