New engine rebuild, glowing exhaust

[Jason]

I just finished doing an engine rebuild and DPI Spec II upgrade. I started the engine for the first time and began to do the cam break in procedure. After running the engine for about a minute at 3000 rpm the exhaust manifolds started to glow red. At this point afraid of damanging something I shut the engine off.

On the advice of Josh at DPI I started the engine and briefly let it idle while I checked the ignition timing (was at 9 degrees TDC, so I set it to 13) and attempted to adjust the mixture using a dwell meter. I didn't get far with that because I had what appeared to be a suddenly loss of oil pressure. That turned out just to be a bad oil pressure sender.

So before I start it up again, I'm looking for any suggestions or advice. I assume that the ignition timing at 9 degrees wouldn't be off enough to cause the problem. Is that correct? I don't have much experience with working on the fuel system, since that has worked flawlessly ever since I've owned the car. I don't want to let the engine sit and idle while I troubleshoot things, because the cams haven't been broken in yet. But until it's fixed I can't run the engine at higher rpm for any length of time.

What I know so far:

Engine starts immediatly and idles at 850 rpm. No sputtering, misfiring, or other strange sounds
Engine revs to 3000 rpm without sputtering, misfiring, or other strange sounds.
Frequency value buzzes.
Idle speed motor is running.
Oil pressure is good. 65 to 70 psi at idle, measured with an external oil pressure tester.
There doesn't appear to be any major vacumm leaks. I'm trying to get hold of a small mirror so that I can double check that the idle motor tube is in the fuel distributor correctly.
And this probably doesn't mean much, but other than the small head gasket leak that prompted the rebuild, everything was working fine before I took things apart.

Given that the engine seems to run fine, is it still possible I've somehow messed up the cam timing? Is it worth pulling the timing cover to check, or are there other things I should check first? Does anyone know how many chain links there should be between the crankshaft mark and the cam mark? When I assembled things I went by the marks on the chain, but they were faint, as the paint or whatever it was had almost completely flaked off. I'm guess now that the chains have been spun with oil the marks will be almost impossible to see.

Any help would be greatly appreciated.

Thanks

- Jason

[WelmoedJ]

I I'm trying to get hold of a small mirror so that I can double check that the idle motor tube is in the fuel distributor correctly.

Press down the metering plate and use a flashlight.
You can see the pipe (if fitted correctly) in the left down corner of the mixture unit.

[Jason]

Press down the metering plate and use a flashlight.
You can see the pipe (if fitted correctly) in the left down corner of the mixture unit.

Ah. Cool. Thanks.

I can see the pipe, so I guess no vacuum leak there.

[dmc6960]

Not knowing any history of everything that was done/replaced...

Any change with the fuel distributor, venturi, injectors during the rebuild? Engine run fine before the rebuild?

If yes on both, you'll definately need to reset your base fueling. This is called "cracking the injectors".

http://dmctalk.org/showthread.php?4995-CO-screw-starting-point&p=70939&viewfull=1#post70939


Pull out all of the injectors and place them in glass jars. Jump the fuel pump to run continuously. Now, turn the screw clockwise until they start spraying fuel. Finally, back it off CCW until they just barely stop spraying. Ideally if the injectors are in good shape none will be dripping at this time either.

[Jason]

Not knowing any history of everything that was done/replaced...

Any change with the fuel distributor, venturi, injectors during the rebuild? Engine run fine before the rebuild?

If yes on both, you'll definately need to reset your base fueling. This is called "cracking the injectors".

http://dmctalk.org/showthread.php?4995-CO-screw-starting-point&p=70939&viewfull=1#post70939

It was all working fine prior to the rebuild.

Nothing in the fuel system was replaced or changed. It was just disconnected and removed in order to pull the engine. I didn't even try cleaning the fuel distributor/mixture control unit assembly for fear of messing it up. I've removed the fuel system before (changing the waterpump, etc) without problems. Of course that doesn't mean I didn't somehow mess something up this time.

As far as what was done, new bearings, pistons, cylinder liners, timing chains, chain tensioners, heads (DPI Spec II), cams (DPI Spec II), exhaust (DPI), valve covers, oil pan, timing cover, intake manifold, intake manifold to throttle pipe, oil pressure senders (one of which failed after two minutes. argh!!), water pump, water pump temp sender, head temp sender, cooling hoses, and vacuum hoses.

[Dangermouse]

Plugged catalytic convertor?

Don't know if that would cause the manifold to glow or just the cat?

[Nicholas R]

I had a glowing cat once. Turned out my injectors were pretty plugged causing poor fuel flow and poor ionization causing the engine to run super lean. A lean fuel mixture runs a LOT hotter than one with the correct fuel mixture.

[deloumis]

Plugged catalytic convertor?

Don't know if that would cause the manifold to glow or just the cat?

Possible but he mentioned he had new exhaust. I would say timing or fuel

[Ron]

If a vacuum leak is causing it to be that lean, you might be able to catch it with cigar smoke...


You might want to estimate the expected timing for the specified break-in RPM and have the timing light ready to get a quick check:

Ignition Timing: 13° ± 2° B.T.D.C. at 775 ± 50 rpm

Centrifugal Advance:
1000 rpm = 00°
2000 rpm = 10°
3000 rpm = 14°
4000 rpm = 20°

Vacuum Advance:
05 in HG = 03°
10 in HG = 12°
15 in HG = 20°
(This one might be lower than you think with those cams, but should move some when you pop the line on and off at the distributor....)

Add, Ignition + Centrifugal + Vacuum = 13 + ? + ?

[DMC5180]

Several years ago I had a Glowing Header situation. That one turned out to be a a Stuck partially open ISM. The car started fine and seemed to Idle normally, BUT as the engine warmed up the Idle began increase quickly to 2000 RPM. This is when I saw the exhaust glowing. The Circumstances surrounding this issue, were that the car had been sitting a few months in an unheated building (possible corrosion). Plus carbon build-up in the ISM valve end bearing caused the valve to become frozen. I was able to free it up using Light machine oil as solvent and manually working the valve. It idled normal after that no more glowing headers.

[David T]

Glowing exhaust=WAY too rich, the excess fuel is burning in the exhaust system. My vote is for a stuck plunger in the metering unit.
David Teitelbaum

[Jason]

Glowing exhaust=WAY too rich, the excess fuel is burning in the exhaust system. My vote is for a stuck plunger in the metering unit.
David Teitelbaum

Too rich or too lean? I've heard both. The manifolds were glowing, the cats and muffler were not.

Is there a way to check if its a stuck plunger short of disassembling things? The air sensor plate seems to move up and down freely.

[deloumis]

Too rich or too lean? I've heard both. The manifolds were glowing, the cats and muffler were not.

Is there a way to check if its a stuck plunger short of disassembling things? The air sensor plate seems to move up and down freely.

Does it move freely with the car on?

[Jason]

Does it move freely with the car on?

I didn't try pushing on it when the car was running, but it appeared to be doing the right things in response to throttle and airflow changes.

[Jason]

I pulled the injectors, put them in jars, and jumpered the RPM relay. Now I feel resistance when I push on the air sensor plate. When I push it down the injectors start spraying. When I release it they immediately stop. So no stuck plunger.

I did the "cracking the injectors" procedure, and had to turn the adjustment screw almost two turns to get the injectors to start spraying. So I though maybe the problem was that it was running to lean. Started it up, ran for about 1 and a half minutes at 3000 RPM, and the exhaust manifolds started glowing again. Exhaust temperature at the tailpipe was 300C (is that normal?).

I shut the engine off and let the glowing stop. Now thinking maybe it is too rich I tried adjusting to toward the lean side. I started the engine, let it idle, and turned the mixture screw counter clockwise until the engine started to stall, and that backed off a tiny bit. Then ran at 3000 RPM for a little less than a minute. At this point I noticed I was getting a fair amount of white smoke out of the exhaust. I didn't notice what the exhaust looked like before because I'm running the car in a garage with a hose venting the exhaust outside. So I shut the engine off. Time to think and do some more research.

Should the white smoke scare me, or could it just be because the new rings haven't seated yet? It doesn't smell like burning coolant. Also, the inside of the exhaust hose where it vented outside seemed to have a thin film of black soot. Does that mean anything?

Does anyone know what the exhaust temperature should be at the tailpipe? What should it be in the exhaust manifold? I was thinking of putting a temperature probe in the lambda sensor port. That way I could tell for sure if combustion temperatures are too high, and if it's a mixture problem I should see the temperature change as I adjust the mixture.

[DMC5180]

Originally you lead us to believe you were seeing glowing exhaust at 850 rpm which is not normal. Now your seeing glowing exhaust at 3000 RPM. Glowing at 3000 is possibly normal. When was the last time anyone watched the exhaust system while holding the engine at 3K. Especially with the thin wall tubing of headers. 1100 - 1350 F is pretty typical for sustained RPM exhaust gas temps.

[Jason]

Originally you lead us to believe you were seeing glowing exhaust at 850 rpm which is not normal. Now your seeing glowing exhaust at 3000 RPM. Glowing at 3000 is possibly normal. When was the last time anyone watched the exhaust system while holding the engine at 3K. Especially with the thin wall tubing of headers. 1100 - 1350 F is pretty typical for sustained RPM exhaust gas temps.

Sorry. I thought I was clear that I was only running the engine for any length of time at high rpms because the cams haven't been broken in yet. I did let it idle for about a minute and didn't see any sign of glowing.

The glow isn't a dim glow. It a fairly bright visible in daylight looking like the manifold is about to melt glow.

[opethmike]

Mine did that during cam break-in. I ran for ~20 minutes at ~3,000 RPM. 19 degrees of timing, 14.0 AFR.

[Jason]

Mine did that during cam break-in. I ran for ~20 minutes at ~3,000 RPM. 19 degrees of timing, 14.0 AFR.

Glowed brightly? Any nothing melted and no damage?

[Jason]

Mine did that during cam break-in. I ran for ~20 minutes at ~3,000 RPM. 19 degrees of timing, 14.0 AFR.

After about two minutes the glow is bright enough that I've been scared to let it run. It looks like the headers have been painted red.

[opethmike]

Glowed brightly? Any nothing melted and no damage?

Bright glow. Nothing melted, no damage.


After about two minutes the glow is bright enough that I've been scared to let it run. It looks like the headers have been painted red.

Yep.

[Ron]

Mine did that during cam break-in. I ran for ~20 minutes at ~3,000 RPM. 19 degrees of timing, 14.0 AFR.
I'm curious as to why your timing was that low...13° initial setting, plus 14° for centrifugal @ 3000 RPM, is 27° (not to mention any the vacuum advance would add)??

[opethmike]

Sorry Ron, let me clarify, 19 degrees of base timing.

[Dangermouse]

Not sure that this is any use in this discussion, but it's just an awesome photo.

From a TVR testbed.

http://dmctalk.org/attachment.php?attachmentid=14938&d=1325770591

[David T]

If it is not a stuck plunger you have to keep looking for something else that is allowing raw fuel to get into the exhaust system. Tight valves, valve timing way off, something is WAY OFF. I am assuming it is both exhaust manifolds so it is on both sides of the motor, not one side or one cylinder. Since you say this is on a newly built motor you probably have something reassembled wrong. A stuck plunger would have been an easy fix.
David Teitelbaum

[Jason]

If it is not a stuck plunger you have to keep looking for something else that is allowing raw fuel to get into the exhaust system. Tight valves, valve timing way off, something is WAY OFF. I am assuming it is both exhaust manifolds so it is on both sides of the motor, not one side or one cylinder. Since you say this is on a newly built motor you probably have something reassembled wrong. A stuck plunger would have been an easy fix.
David Teitelbaum

That's what I would think too. Though I was very careful with the timing and valve clearances. And it brings up the question of why the exhaust was glowing during break in on Mike's apparently correctly assembled engine.

Is there some way to measure if it really is excess fuel in the exhaust? I'd like to have a better understanding of whats going on before I start disassembling things looking for the problem.

[ramblinmike]

If it is not a stuck plunger you have to keep looking for something else that is allowing raw fuel to get into the exhaust system. Tight valves, valve timing way off, something is WAY OFF. I am assuming it is both exhaust manifolds so it is on both sides of the motor, not one side or one cylinder. Since you say this is on a newly built motor you probably have something reassembled wrong. A stuck plunger would have been an easy fix.
David Teitelbaum

CSV firing non-stop? Unplug it and try again?

[Jason]

So if it really is too much fuel would I be able to see that right away if I put a wide band O2 sensor in the unused exhaust bung?

[Bitsyncmaster]

So if it really is too much fuel would I be able to see that right away if I put a wide band O2 sensor in the unused exhaust bung?

With that high heat, not sure the wideband would read correctly. You could maybe check it at the tail pipe but not keep it running for long.

It maybe your exhaust valves are opening to soon but it's sounding like you checked the timing many times.

I would think it would not run right if you had some plug wires crossed.

[Jason]

With that high heat, not sure the wideband would read correctly. You could maybe check it at the tail pipe but not keep it running for long.


With a self heating sensor shouldn't I be able to get a decent reading during the first minute before things start glowing?

[Bitsyncmaster]

With a self heating sensor shouldn't I be able to get a decent reading during the first minute before things start glowing?

I would guess you could read something close. If you have raw gas it won't read accurately. The wide band normally is ready to read in 15 seconds.

[David T]

Even if you could get an A/F reading you can already tell it is WAY too rich, otherwise the exhaust would not be glowing! Getting a very rich reading will only serve to confirm a fact you can already deduce. It can't tell you why. You are going to have to go over all of your work and figure out what is wrong. Start with a compression test and a leak-down test and then move on to valve timing and adjustment. Ignition timing would not cause this. Pull the plugs and see if all of the cylinders are firing. Maybe you messed up the firing order in such a manner that it runs OK but not right?
David Teitelbaum

[Jason]

Even if you could get an A/F reading you can already tell it is WAY too rich, otherwise the exhaust would not be glowing! Getting a very rich reading will only serve to confirm a fact you can already deduce. It can't tell you why. You are going to have to go over all of your work and figure out what is wrong. Start with a compression test and a leak-down test and then move on to valve timing and adjustment. Ignition timing would not cause this. Pull the plugs and see if all of the cylinders are firing. Maybe you messed up the firing order in such a manner that it runs OK but not right?
David Teitelbaum

For the compression test I got 115 120 110 112 107 112 psi. Is that too low or is that ok for Spec II cams and unseated rings?
All plugs look the same, slight browning of the ceramic at the tip but otherwise clean. I don't have anything to do a leak down test.

The trouble with the timing and valve adjustment is that I was very careful when doing both, and all cylinders seem to be behaving the same. So if the either is wrong it most likely because I misunderstood something about the procedure, rather than just a mistake. So without being really sure that one of those is wrong, if take it apart and redo it, I'll probably end up with things the same.

Too rich doesn't explain why Mike had glowing headers with a measured AFR of 14. Unless maybe raw fuel would throw the sensor way off.

[Jason]

Mine did that during cam break-in. I ran for ~20 minutes at ~3,000 RPM. 19 degrees of timing, 14.0 AFR.

Were you by any chance using some sort of exhaust hose to redirect the exhaust somewhere, or were the tail pipes unobstructed?

[opethmike]

Were you by any chance using some sort of exhaust hose to redirect the exhaust somewhere, or were the tail pipes unobstructed?

They were unobstructed.

[Ron]

Ignition timing would not cause this.
David Teitelbaum
David, try retarding the timing on any engine until it barely idles, it WILL make the exhaust glow every time.

Retarded Timing => Incomplete Burn => Unburnt Fuel In Exhaust = Marshmallow Time

======
Usually,
Glowing Converter => Restricted, or, Rich (Incomplete burn in cylinder).
Glowing Manifolds => Lean (Lean ignites sooner, burns hotter and leaves hotter).

[Jason]

David, try retarding the timing on any engine until it barely idles, it WILL make the exhaust glow every time.

Retarded Timing => Incomplete Burn => Unburnt Fuel In Exhaust = Marshmallow Time

======
Usually,
Glowing Converter => Restricted, or, Rich (Incomplete burn in cylinder).
Glowing Manifolds => Lean (Lean ignites sooner, burns hotter and leaves hotter).

And I've got glowing manifolds, which is why I'd like to find a way to tell if its too rich or too lean before I start pulling the engine apart.

[Ron]

Pull the plugs, they might tell you a lot (Carbon/Soot => Rich; Blisters/Snow White => Lean.)

Have you checked your timing @ 3000 RPM?

You said Manifolds, then later said Headers...which do you have?

[Jason]

Pull the plugs, they might tell you a lot (Carbon/Soot => Rich; Blisters/Snow White => Lean.)

Have you checked your timing @ 3000 RPM?

You said Manifolds, then later said Headers...which do you have?

Plus look clean, with a slight tanning of the previously white ceramic at the tip.

Its headers. A spec 1 exhaust. https://www.deloreanindustries.com/shop/catalog/product/gallery/id/198/image/399/

I haven't checked the timing at 3000. Would a bad vacuum advance be enough to cause glowing?

[David T]

I don't think you can turn the distributor enough to get that bad if it is installed correctly. As you noted it would barely run anyway and from the poster's description, it doesn't sound as if that is the problem. Since the motor was disassembled anything is possible I suppose. The main point is EVERYTHING that was done to the motor is now suspect and must be checked until the problem is found. No possible mistake can be eliminated until the problem is solved and the headers stop glowing. As with most things, it is not always "just" one thing. Even if you do manage to find something wrong it doesn't automatically mean EVERYTHING ELSE is correct. Keep checking.
David Teitelbaum

[Ron]

I don't think you can turn the distributor enough to get that bad if it is installed correctly. As you noted it would barely run anyway and from the poster's description, it doesn't sound as if that is the problem. Since the motor was disassembled anything is possible I suppose. The main point is EVERYTHING that was done to the motor is now suspect and must be checked until the problem is found. No possible mistake can be eliminated until the problem is solved and the headers stop glowing. As with most things, it is not always "just" one thing. Even if you do manage to find something wrong it doesn't automatically mean EVERYTHING ELSE is correct. Keep checking.
David Teitelbaum

lol that "if" word will burn you every time if you let it.

I agree. But as you say, there may be more than one thing going on...it could easily run OK at idle and nowhere else...(as below for example).
Not a lot to go on with it parked... might fall on it's face if you drove it...could be valve timing/adjustment...ANYTING w/o checking performance (which he can't do until the cams are broke in).
I'm just saying check the basics which could cause or contribute...easy first, keeping in mind the cams need to be broke in correctly...



Plus look clean, with a slight tanning of the previously white ceramic at the tip.

Its headers. A spec 1 exhaust. https://www.deloreanindustries.com/shop/catalog/product/gallery/id/198/image/399/

I haven't checked the timing at 3000. Would a bad vacuum advance be enough to cause glowing?
That is what you want WRT the plugs...

Yes, bad vacuum advance could, depending on just what was "bad".... Say the pluming was wrong and/or the thermal vacuum control valve was bad and/or the vacuum solenoid was hung, miswired...etc. such that vacuum was being applied at idle -- Your base setting could be off (too low), causing incomplete burn...

Glowing or not, you need to know your TOTAL advance is correct! Easy to do, so just check it! Try this:


Remove the line going to the distributor and set the Base Timing to 13° BTDC @ 750 RPM.
See if the timing changes when you replace the line -- It should not.
Remove the the line to the distributor again.
Check the Centrifugal Advance against the values in post 9 (http://dmctalk.org/showthread.php?5705-New-engine-rebuild-glowing-exhaust&p=81333&viewfull=1#post81333) (Add 13°! Don't worry if not exact...)
Note: At your break-in RPM (3000) you should have about 13+14=27° (w/ line disconnected). (Turbo distributor setups should halt advancement at >4-5000 RPM or so, depending....)
(I haven't seen the expected values for vacuum on a stock engine WRT RPM, but aftermarket cams would throw them off anyway.) If you can get a "free" AutoZone vacuum tester (it will have a hand pump...), you could connect it to the distributor with the engine off and verify operation with the chart beforehand... Then put a "Tee" in the line and add the amount for the vacuum you read @ 3000 RPM to know exactly what the total advance should be...


If this checks out, contact Josh and run through everything you did with him...people say he is quite helpful and knows the setup intimately....

[Jason]

Assuming coolant temperatures are good, oil pressure is good, a wide band O2 sensor reports a reasonable mixture, and the exhaust isn't actually melting, how safe would it be to run through the break in procedure, and then try to fix the glowing. If the cam timing were a bit off would it damage damage the valves?

It seems this would be much easier to fix if I could let it idle while troubleshooting or try driving it to see how the engine responds under load.

I'll double check the valve clearances and cam timing but I expect I'll find that they look correct.

[Bitsyncmaster]

Does it still glow at normal idle RPM? Why not do all your troubleshooting at that RPM

[Jason]

Does it still glow at normal idle RPM? Why not do all your troubleshooting at that RPM

I don't think it glows at idle, but I can't be sure because I haven't let it idle for very long. I don't want to have it sit and idle until after the cams have been broken in. That's whats making diagnosing the problem extra difficult.

[Jason]

Well, I found a vacuum leak. The metal ring that holds the idle motor tube o-ring to the mixture unit had come come loose and slid up the idle tube together with the o-ring.

I haven't tried starting it up again, so I don't if fixing that will cure the glowing headers, but somehow I doubt it.

[WelmoedJ]

Well, I found a vacuum leak. The metal ring that holds the idle motor tube o-ring to the mixture unit had come come loose and slid up the idle tube together with the o-ring.

I haven't tried starting it up again, so I don't if fixing that will cure the glowing headers, but somehow I doubt it.

You mention a metal ring.
Originally the part to keep the O-ring locked-up is a brass cup.

Should you indeed have a ring (washer-like) to lock-up the O-ring, trty and find something that you can make fit tightly.
My D had no brass cup and therefore I used a copper washer that I hammered until a bit oversized.
Stayed in place for a long time, however you need some patience and hammering before it fits OK.
I now have added a copper plate with the proper hole and this plate is screwed onto the mixture unit and sits snugly to the copper ring and O-ring.

[Ron]

I haven't tried starting it up again, so I don't if fixing that will cure the glowing headers, but somehow I doubt it.

That's a lot better than other things you could have found... -- Have faith!
(And have all of your test eqipment set up before you try it ;-)

[Jason]

I got through the break in procedure!

I fixed the idle tube vacuum leak, removed the exhaust hose, and pushed the car out into the sunlight where its harder to see the scary glowing. :)

So I'm not sure exactly which of those fixed it, but I got through a 20+ minute run between 2500 and 3000 RPM. Engine temperature and oil pressure were good, no more white smoke, and the exhaust headers looked normal.

It started out with an air fuel ratio of 12, but after it warmed up it went to around 16.8 no matter what I did with the mixture screw. At the end of the run when I let it idle it would oscillate between 1500 RPM and almost stalling until I turned the mixture screw toward lean, and then it settled down and idled normally.

And then when I went to back the car up the driveway and into the garage I discovered I messed up the shift linkage and couldn't get it into reverse. Doh! After some pushing to get the car turned around it drove forward up the driveway and into the garage under its own power.

Now that I've screwed up the mixture messing with it when I didn't need to, is a reasonable way to get it back to unplug the lambda sensor, warm up the engine, let it idle, and adjust the mixture screw until I get an AFR reading of around 14.7?

15011

[Bitsyncmaster]

I would suspect your O2 sensor it shot if it was installed in that glowing exhaust. Are you still running the closed loop Lambda system?

[Ron]

Now that I've screwed up the mixture messing with it when I didn't need to, is a reasonable way to get it back to unplug the lambda sensor, warm up the engine, let it idle, and adjust the mixture screw until I get an AFR reading of around 14.7?Use a dwell meter and follow the procedure in the manual!
(Remember to use four (4) cylinder setting and plug the access hole when reading...)

If that gives you a any problems- I'm with Dave on the O2 sensor...You might get away with the heat since it was at the headers...but with that, the white smoke, breaking it in..., and probably age(?), I'd replace it for GP and peace of mind -- You played it smart breaking in the cams, now for the rest of the engine....

[Jason]

I would suspect your O2 sensor it shot if it was installed in that glowing exhaust. Are you still running the closed loop Lambda system?

The fuel/emissions system is basically stock. With an additional wide band O2 sensor that's just hooked up to a gauge.

The wide band sensor was only installed after I fixed the vacuum leak, so never saw the glowing exhaust.

As for the narrow band one, its new, the part of the exhaust where it sits didn't glow, and it was only run under those conditions for a short period of time, so I'm hoping its still ok. I could put the old one back in and see if it makes a difference.

[Jason]

Use a dwell meter and follow the procedure in the manual!
(Remember to use four (4) cylinder setting and plug the access hole when reading...)


The service manual says to use the 6 cylinder setting. And calls for an exhaust gas analyzer which I don't have.

[Bitsyncmaster]

The service manual says to use the 6 cylinder setting. And calls for an exhaust gas analyzer which I don't have.

Dwell readings for the Lambda use your 4 cylinder to get the readings shown in the manual.

[Ron]

The service manual says to use the 6 cylinder setting. And calls for an exhaust gas analyzer which I don't have.Yes, that is in Section D:04:01...
Skip to D:04:14 and use "Pulse Ratios" on D:04:15 (and use 4 cylinder setting ;-).
Make sure all other tune up settings, etc are correct first! -- Check after anything is done to the engine in the future...

If you don't have a dwell meter that has a 4 cylinder setting, use 8 cylinder and cut value in half.
It sounds odd, but try it, you'll like it!

[alvanjudson]

I had a glowing cat once. Turned out my injectors were pretty plugged causing poor fuel flow and poor ionization causing the engine to run super lean. A lean fuel mixture runs a LOT hotter than one with the correct fuel mixture.
I just read this post and have to say that Nick is right on the money. I had a glowing cat after a total engine rebuild, new injectors and pipes and I had the mindset that it had to be running rich. (I had myself believing that excess fuel was being burnt in the cat and it was having to work double overtime which is a situation that I've seen with fuel injection many times) Eventually I counter-intuitively richened the mixture and the problem was totally cured.

[TTait]

They were unobstructed.

Any chance packing materials got into the exhaust system on shipping?

[Ron]

I just read this post and have to say that Nick is right on the money. I had a glowing cat after a total engine rebuild, new injectors and pipes and I had the mindset that it had to be running rich. (I had myself believing that excess fuel was being burnt in the cat and it was having to work double overtime which is a situation that I've seen with fuel injection many times) Eventually I counter-intuitively richened the mixture and the problem was totally cured.
Yep..this (and not being clear on what part of the exhaust is glowing) is why arguments get started as to whether glowing exhaust means rich or lean....it can be either.
Usually, assuming there is only one thing wrong, if the manifolds/headers are getting too hot because it is too lean (ignites sooner, leaves hotter), and, if the cats are getting to hot, it is too rich (finishes burn down stream, as you mentioned...). But high RPM v/s low v/s both and other things (eg timing) can call off all bets and here we go...LOL

[DMC5180]

Just incase anyone ever wondered how hot things are based on color, here's a nice chart:

15026

My polished Magnaflow muffler shows a faint to light straw coloration therefore I know the body is getting up too about 400-425 F˚