glowing manifolds

[jamal]

I know this is not the right forum but I've posted elsewhere with no response. You guys know your stuff and am sure you can help that is why I ask. I finally have my 98 running again. I broke the new engine in tonight. The only thing that I thought was strange was while I was breaking the engine in the manifolds started glowing. It was dark out and when I shined a flashlight on them they didnt look red anymore. Was it b/c it was dark and was running engine between 2500 and 3000rpm without any moving air? I couldn't find any vacuum leaks and everything was sealed from mass air back to the intake. Ran good and oil pressure was around 80 at start up and droped to around 45 when warm and temp stayed in normal range. Anything to worry about or is it normal? I never broke an engine in at night so I have no idea if it is normal or not.

[LooseCannon]

My friend's 78 blazer did the same thing. It was caused by running to lean.

[Cat Fuzz]

Running too lean, plugged cat or other exhaust restriction.

[jamal]

but my fuel is controlled by computer. Think my timing might be off? didn't get any engine light. will look again for vacuum leaks in the am

[jimfulco]

Retarded timing?

[chevman-67]

Check the cataletic converters they are probably plugged or muffler is plugged.or your doughnuts in the exhaust are blocking part of yourmanifold to y-pipe .sounds like I would start there first.

[Randy70C-10]

Either running too lean or you have a BIG vacuum leak. Everything that I've seen from plugged cats usually makes everything "behind" them glow.

[jamal]

was my timing it was advanced too much

[mocwon]

Agree w/Randy. Seen cats back glow when cats are plugged but not forward.

[roger0080]

I was driving a UPS truck that had an old Ford 6 cylinder in it at about 55 mph down the freeway when the engine cover in the cab blew backwards exposing the engine and much to my surprise the exhaust manifold was all orange! Never thought much about what color if any the manifold changes while we are driving. I wouldn't worry about it. Hope this helps.

[al's71gmc]

sounds like you already got it, but i had glowing manifolds on a toyota, and it was the timing.

[ZOOMY]

Most engines will get the manifolds glowing at night if you run them long enough at 3k. It happens quicker with headers. Exhaust ges temperature is about 1500 degrees at ideal mixture. It drops off if it's runnung lean or rich from that point.

[jamal]

thought I had it fixed they are still glowing. I drove it at night pretty hard and they turned bright red. I cant find vacuum leak or anything and timing is dead on. this is a brand new longblock and hate to mess it up as I dont have money to buy another one. Engine is not getting hot or anything, just manifolds. Should I worry? This truck has a 3 inch body lift so it allows me to see manifolds, and may just not have noticed in other vehicles. I bought it with a spun main so I have no idea if it did it before. I am confused as hell please help could I have valves too tight?

[gator2511]

You are too lean. If you are using an electric fuel pump check your fuel pressure. Had a buddy's electric fuel pump that went bad but it didn't just die. It reduced the fuel volume and pressure to the engine, the engine ran lean, manifolds glowed orange. Your computer may be happy with fuel information as far as it knows but it doesn't know the pump can't deliver enough gas. Its worth a try. Two months later mine went but it died suddenly.

[lowrider79]

Try changing the fuel filter as well

[Richard]

I saw that happen years ago on a friends engine. The cam flattened out during break-in. I hope everything is okay.

[jamal]

pulled plugs and they look great, no signs of running lean or rich. It is running right and the timing is dead on with a scan tool. Has to be ok if plugs are looking good and timing is dead on right?

[Randy70C-10]

Try advancing the timing one or two degrees and try again. Timing advanced too much won't make them glow (normally) but having it retarded too much will. What happens is if the timing is retarded too much (meaning it's firing too late) then you have fire going out of your heads instead of burnt gases (exhaust). That's the best I can explain it (I'm a redneck) You should see what timing does to a 6:71 blown 350 when it's retarded too much. The headers turn white!

[jamal]

actually when I thought I was adjusting timing I wasn't. the timing on vortecs is non adjustable, and I was only confusing computer. Could it be improper ex valve adjustment? Everything seems right though.