Our original exhaust manifold needed replaced due to a bad damper spring.....so we ordered the one thru Dorman per suggestions here.

It has a port on the collector that I would assume is for an 02 sensor for later model engines. It came with a bolt/plug which we have in right now.

Safe to use that for an AFR meter 02 sensor?

Also, since an AFR meter uses an 02 sensor, how long can an engine run rich and not ruin the 02 sensor?

That Port is More likely for an Air Injection port from an air pump - I am not sure that Slant's every had 02's from the factory.

Anyway if you use a Wide band 02 you will be fine - I run in the race car at 12.0-10.5 continually on drag passes and it is not damaged at all.. They also should have heaters built in that help them survive a bit.

Best of luck!


Greg

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Well, I figured that maybe into the late 70s they may have ?????

You did bring up an interesting point though.....the air injection stuff.

Our car appeared stock when we got it and while it has an air pump, it had one big hose hanging from the pump that goes to nowhere..... another big hose goes from the pump to a metal tube with a valve in it that goes to the rear of the head......the hose just hanging there now actually pumps air out.,,..depending on RPMs and makes some noise as well....wondering if that hanging hose used to go to a port like our new manifold has? IE maybe the exhaust manifold on our car wasnt stock at all?

Actually, 80s era slants DID use an O2 sensor in the exhaust manifold mounted inboard and up from the flapper on the rear of the exhaust "tower." The primitive feedback carb lean-burn systems had an oxygen sensor. I need to bite the bullet and order a couple of those new exhaust manifolds for FI conversions.

The AIR pump injection points are the rear of the head, directly downsteam of the exhaust manifold to pipe junction, directly into the first "mini-ox" catalytic converter just downstream of the manifold to pipe junction, and directly into the catalytic converter in single cat systems. Slants did not have air injection directly into the exhaust manifold.

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I had to make my own gasket for the tube-to-head connection.....but hey, I am wondering.....if the air pump is injecting air into the head, could that be causing issues elsewhere like rough idle and lean cylinder 5?

This is purely anecdotal, but I have come across three 80s era slant six heads with the port injection and all of them had a cracked exhaust valve. I think the lean burn system can run too lean and burn a valve and the air injection can cuase thermal cycling problems on the backs of the exhaust valves. I have no scientific testing or verification to back this up. THis is just something I have seen. :shrug:

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Casually looking for a Clifford hyperpak intake for cheap.

I have one of those repro manifolds myself, and yes you can thread an aftermarket wideband O2 sensor in there as long as you're not trying to use a turbo downstream of it (which I am).

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
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Bring it over my house i can tell you whats what on it.

I had a bone stock 80 slant for a while..
Greg

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The stock o2 port may be too close for a wideband, you can overheat them.

It's an O2 sensor port. The Slant-6 air injection and pulse-air systems did not route to the manifold, they routed to the cylinder head and catalytic converter.
They did, starting at various times in the '80s depending on vehicle and market.

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Supposed to go to one or another catalytic converter (depending if your car originally had one or two). This is the downstream air injection.
That's all correct. Upstream air injection. The two hoses are connected not directly to the pump itself, but to a device on the back of the pump called an air switching valve or air diverter valve. It sends air to the upstream or downstream location depending on engine operating temperature and load. This device has to be controlled correctly to function properly, which means the various thermal sensors, vacuum hoses, and (if applicable) control boxes on the firewall need to operate correctly. If not, finding repair parts can be a real bear and it might be better at that point to put together a non-stock but basically functional alternative air injection control system.
No. There are no Slant-6 exhaust manifolds with air injection ports in them.
No. Your idle issue is caused by improper fuel mixture. Adjusting a carburetor doesn't look like turning the mixture screw/s until you hit the limiter caps and calling it good, it looks more like what's described here.

(If that valve in the pump-to-head line is faulty, it will allow exhaust into the air pump and switching valve, cooking them. I have replacement valves if you need one.)

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Too many people who were born on third base actually believe they've hit a triple.

So my "too-lean lean-burn plus cold air injected on the back of the exhaust valve cracking it" theory holds no water? I thought it was rather clever.

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Casually looking for a Clifford hyperpak intake for cheap.

Thanks- yeah that makes sense I guess. The cat on the car looks aftermarket and does not have an air input.
Yep, we have that whole big mess.
Well, while I would like to say its all there, I cant say for sure. Its a nightmare of hoses and tees and valves etc. What do you suggest as far as the "non stock but basically functional alternative" ? Why do we really NEED the air injection , environmental and regulation issues aside? What real world affect does the air injection have on how the engine runs?

Yeah, I have followed that process. I can get the idle to drop etc as in that outline. It doesnt affect the rough idle. That, plus #5 being so lean, I am wondering if we have a vac leak as has been suggested.

Also as I mentioned , the limiter caps are on the carb as manufactured. My assumption was that the initial "seating/back out 2.5 turns" process would have been performed on the carb and then the caps installed, enabling a dealer etc to take the carb, install it and tweak within that range accordingly on a stock engine. Otherwise what is the point of the caps?

I understand we have a cam now and that changes things.....so your advice is to remove the caps? They just pop off I guess?
I have seen mention of the replacement valves before.....I guess you have to cut the old valve out then, as ours has one solid pipe with the integral valve in it. I blew/sucked at one end and it seemd like it was working "one way".

I do know that the other hose (the one that should be connected to the cat) makes a racket , off and one, as idle and load changes.

I like that tool you linked to...not available at the link anymore so I will look elsewhere maybe......a visual way to see the combustion. Cool........may try to go that way or the AFR gauge......the colortune gizmo is the easiest though I guess......gonna have to confirm what size spark plug threads we use....the one I found was "14mm for motorycles". One issue with our car is clearance....it looks like a long-ish gizmo.....would not fit in some of our plug hols what with the alternator, lines etc in the way......

OK, wrong cat (meow!) for the car. You can buy a cheap converter easily, which sounds like what the previous owner did. They're junk, warranted only for 25,000 miles and minimally effective. But for a carbureted vehicle like yours, you need a heavy-duty, high-load converter -- anything less is a waste of time and money and will quickly need replacement again. The trick here is to get a California-spec converter. These have to be type-approved to much stricter regulations that require much longer durability, so you get your money's worth in the long run. The one to buy is this one (that's a very good price on it, too). Notice it has the air injection tube ready for hookup to your car's dangling air injection line, using connector supplies like this. Another good idea while the converter's being installed is to have the headpipe (the pipe from the engine to the converter) wrapped with this thermal insulation, which will do several good things: it will keep the exhaust extra-hot on its way into the converter, which facilitates maximum converter efficiency and reduces the likelihood of converter damage by improper fuel/air ratio. Also it keeps the underhood temperatures cooler and stops the hot exhaust pipe from cooking the engine oil where the pipe passes under the oil pan.

What about just deleting the converter completely? You could probably get away with it, but read this before you decide.
Depends how much of your existing system is intact and functioning. Part of refurbishing a car of your car's age is learning the details of the hoses and tees and valves. It's only a nightmare until you read up on it and learn how it works -- it really isn't as complicated as it looks. Do you have the factory service manual?
Because the exhaust coming out of a Slant-6 engine is full of unburnt and partially-burnt fuel. Air injection provides oxygen for that leftover fuel to burn before it leaves the tailpipe, which means cleaner exhaust and the catalyt converter's job becomes possible.
None.

You could. Also, how are your valves adjusted?
I routinely remove them to make carb adjustment easier. They pry off with some careful screwdriver-and-pliers work.
Yep, cut/weld.
Good! It's working, then.
Oops, sorry. Here's the one you'd need.
The long part is just a tubular "scope" (shield to block out ambient light to make it easier to see the light flashes through the glass spark plug). You can use other methods to darken your surroundings and watch the flashes.

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Too many people who were born on third base actually believe they've hit a triple.