Thread: Header Temperatures

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I am just got done breaking in my new motor which is a 383 Tuned Port Injection. All the sensor data looked good, A/F ratio was right at 14.7 and water temp was around 200F.

At about minute 15 my stainless block hugger headers started changing color. At minute 20 at 2000 rpm, the headers were glowing red. I took a infrared thermometer to them and they were all within 15 degrees, around 375F.

My question.....What range are these headers supposed to be running at? Makes me think the motor is running lean but the 02 sensor says everything is good.

Any suggestions or comments?

Thats what happens when you break a engine in,the headers should have came with a warning not to use them on breaking in ,because of discoloration.All the ceramic coated headers say do not use for break in because of the high temps associated with this procedure will discolor the finish,not sure about stainless?
Cherry red glow is good ,white hot is not
I have no answer on the lean condition.........might want to check the plugs for that.

Check the timing. Retarded spark will cause hot headers. 2000 rpm under no load shouldn't make that much heat.

the mechanical timing was set at 8 BTDC. After letting the ECM take control, the timing goes to 23 at idle and 32 at 2000rpm. Right where it should be so the timing is fine.

The glowing headers are my concern. Does 375F sound too hot? Any oil drip onto those headers will catch fire which is bad.

Originally Posted by mrrilla

I am just got done breaking in my new motor which is a 383 Tuned Port Injection. All the sensor data looked good, A/F ratio was right at 14.7 and water temp was around 200F.

At about minute 15 my stainless block hugger headers started changing color. At minute 20 at 2000 rpm, the headers were glowing red. I took a infrared thermometer to them and they were all within 15 degrees, around 375F.

My question.....What range are these headers supposed to be running at? Makes me think the motor is running lean but the 02 sensor says everything is good.

Any suggestions or comments?

In the old days before the A/F gauges where out there we use to run about 1,350 F right at the head where the exhaust bolts to the head it's self for circle track applications.
1,450F for drag engines.
I forgot to add this temp. is for good pistons like a JE and I would not recommend these temps. with a set of $100 hyper's.

Originally Posted by mrrilla

the mechanical timing was set at 8 BTDC. After letting the ECM take control, the timing goes to 23 at idle and 32 at 2000rpm. Right where it should be so the timing is fine.

The glowing headers are my concern. Does 375F sound too hot? Any oil drip onto those headers will catch fire which is bad.

Yes there will be fire if you spill oil on headers
I think you will know if you get a over heating problem and by plug color.
I used to have a chart,dull red 500approx, cherry red 6 or 700,orange is 900 approx and white hot is approx 11 to 1200 degrees. I am sure those temps are far from correct ,but you get the idea.

manifold temp has to be at least 500* ( and 650* to be accurate ) for an O2 sensor to run in closed loop, so it's gotta be hotter than that under break in?

a true S steel move heat better then carbon steel colors of cabon steel are blue is about 600 and red go,s from f750 faint red
blood red f 1050
dark red f1075
med cherryf1275
orangef1725

Originally Posted by Matt167

manifold temp has to be at least 500* ( and 650* to be accurate ) for an O2 sensor to run in closed loop, so it's gotta be hotter than that under break in?

Think he's talking the external temp of the metal, not the temp of the exhaust gas, Matt.....

IMO, 375 for ceramic coated or stainless headers is a bit high... With an ECM, probably not a heck of a lot you can do about it though... Sounds like you're going to have some blued headers..... Might as well get some header wrap, the high underhood temps won't be doing anything good for the performance of the engine.....

I know alot of the F.I. stuff runs alot hotter exaust temps than a carbed ride,.......emissions I guess?Trying to burn all the unused fuel there in the exaust manifold?
Sounds like normal breakin glow to me on the glowing at 20 mins ...whats the temp at idle?
My rams horns were dull red{with carb} in the thin spots after break in and I stoped once in the middle to get a air pocket out of the engine and to let the" almost " fire with the high heat paint cool off.

sounds like everything is ok to me, that is breakin.... since your headers are now blued anyways might as well buy some jet hot and ceramic coat them so at least the high temps wont be coming through as much.....

Running rich will make your headers glow, too. When you run the engine at high rpm, no load (such as during break-in), you carry a lot of heat over into the exhaust as well.

Originally Posted by 76GMC1500

Running rich will make your headers glow, too. When you run the engine at high rpm, no load (such as during break-in), you carry a lot of heat over into the exhaust as well.

Hi rpm "such as during break-in"???
I think what people are doing here is confusing E.G.T. with external temps.