Hello, I am looking to replace my factory exhaust manifolds with smog air pump lines to a none emissions exhaust manifold. The lines are rusty and keeping leaking exhaust and its getting old with the ticking it makes. Looking for a permanent solution to the issue.. Will any Olds 350, 403 manifolds from the 1970s fit the 1984 307 without changing the factory exhaust? I am guessing the manifolds are the same,(correct me if I'm wrong), but will the factory exhaust pipes bolt up to it? Cant find any info about it. Thank you in advance for any info on this.

 

The mid 70's and up are the same outlet angle with any Olds V8 that had a factory catalytic converter. The lines go in the head and goes to the cat, does it not, it has been over 20 years since I saw one of these in the wild. You will be lacking the O2 sensor port as well.

 

First of all, the A.I.R. pipes screw into the HEADS, not the manifolds (this isn't a Chebby), so swapping manifolds doesn't change that. As for what fits, your 1984 307 has 5A heads, which have the same exhaust ports as on pretty much any earlier SBO. The manifolds interchange, and frankly in some cases they are even the same part numbers. The 1985-90 roller cam 307s with the 7A heads have the smaller exhaust ports with the stainless tubular manifolds.

 

After further inspection, you are correct. The lines do in fact come out of the heads. I just assumed they came out of the exhaust manifolds like most cars of the era. So what do i do now? I don't think those fittings are going to come out of the heads nicely, if at all?? Is there something to fix the leaks coming from them that doesn't require removing the heads? They have been crimped, but leak again. I just want a quiet reliable car to drive without breaking the bank.

 

Do what the factory did up here in Canada anyways, plug them. My 81 Delta Olds 307 had factory plugs, as did my 82 parts car I had them, no factory air injection till 83 and no CCC till 86. I also have a set of 4A Olds 403 with same plugs in my garage. Supposedly they aren't NPT, I believe they are fine thread. To fit the factory plugs, the tubes behind those lines need pulled out with needle nose pliers. Heat and a socket are your friend in removing them. Much better chance removing now vs the lines intact with a tube nut wrench.

 

Thanks

 

These are inverted flare threads. Just like brake lines, the seal is on the tapered flare, not on the threads. These are straight threads, not NPT. Yeah, lots of people have forced brass tapered NPT plugs into the A.I.R. ports and the brass is soft enough to deform into a seal. Not my first choice, but it's probably expedient. If you want to do it right, there are steel inverted flare plugs available. I'll also caution that I've had the hex part of the inverted flare nuts break off when I tried to remove them, so there's that.