headers glowing red

[Rob_Roy]

You checked the base ignition timing, good. Did you check to see if the timing advances as the engine rpms increase?

Running an engine lean under load can also cause very high exhaust temperatures.

 

[Buffman]

I've had my headers go red on the dyno from running too lean too

I'd check make sure cat isn't clogged. Otherwise sounds about normal for described conditions

 

[genynnc]

Cam timing can create this... I don't know about a 91 Civic but I've had a bunch of SBC's on a dyno with retarded cam timing for more topend power. A certain amount of retarded cam timing allows the exhaust valve to open slightly when the the piston reaches a few crank degrees after TDC. On the ignition stroke, compbustions slips out of the chamber past the open exhaust valve and into the header or exhaust manifold. Then it flows into the tubes and ignites any raw fuel that is left over in the tubes and primarys.

Maybe a worn timing chain or timing belt (which ever one that the honda engine has) could cause varried valve timing and helped aid in the 'glowing exhaust manifold'?

 

[chevrofreak]

^that doesn't sound right to me.

 

[Merkava_4]

I'm thinking the catalytic converter is clogged too.

 

[NYEngineer]

What type of ignition system does your car have? My buddy has a Mazda Six. One day he calls me up and says the pipe from the manifold to the cat was glowing. He had a bad coil and I guess the unburned fuel from that cylinder was burning in the exhaust pipe. We replaced the coil and no more glowing.

 

[Eddie]

When I worked for J.I.Case company we tested engines at full power for a straight 6 hours. All cast iron manifolds and exhaust pipes 3 foot back from the manifold glowed fire red always. These were new motores just coming off a one hour break-in profile. My dads Pontiac ( excellent condition and tune) would have a cherry red cast iron manifold when we pulled a camping trailer on interste highways. I think it depends on the particular engine, the condition and the load and time running at power. Just from my eye ball experience.

 

[mechtech2]

Are you sure it never did this before?

 

[jinx]

well I took my car to my friends shop today while I was out and he said it my cat wasn't clogged and timing is good.

mechtech2: I'm very sure this has never happened before I go up cypress at least twice a month and pop my hood open every time I park.

 

[cmorr]

Jinx

Do you know how he tested the cat.I have a back pressure test gauge that I screw in the upstream o2 port. Back pressure at idle should be around 1/2 a lb. At 2500 rpm back pressure should be no around 1.5 lbs. The hole drilling method is not accurate.

As I mentioned earlier in this thread I still think it's an exhaust restriction or clogged (maybe partially) cat. If original your at 17 years. Partially clogged you would still have decent performance. I personally would be concerned about heat damage to your engine

 

[mechtech2]

My first guess is retarded ignition timing, as also mentioned by others.
Your base timing is not the whole picture. If you have mechanical and vacuum advance mechanisms, they must be working correctly.
You base timing may be good, but everything else broken, in other words.

 

[SHOZ]

Probably running with just enough load to keep it in closed loop. Running at stoich will do this if pushing enough air through the motor.