my headers are glowing red

[BigBlockSam]

hey guys , i never seen this before on a 440 motor , first the build . it is a fresh 1968 440 hp motor. comp cams Xtreme Energy™ XE268H; cam, 1600 - 5800 RPM Range . freshly rebuilt six pack ,Mallory distributor . when we were breaking in the cam the headers started to glowing red.so we shut it off so it would cool down . i know red means lean but why would it be running lean. any help will be appreciated . 

[A383Wing]

could be also rich with fuel being burned in the headers

[cdr]

not enough timing will do it also.

[RECHRGD]

not enough timing will do it also.

X2.....

[Rubberduck]

Yes, advance your timing. That´s it.

[BigBlockSam]

  thanks guys , that makes me feel better. i've had this motor apart 3 times since we put it in the car  , i won't be able to get to it till monday. but Crazy Jack has my car at his shop ,he's doing a tune on it now . i'll let ya know how it goes , thank you for the help   

[Canadian1968]

yup more timing mine did this on cam break in as well adjust timing... all gone.

[Highbanked Hauler]

could be also rich with fuel being burned in the headers

    same here but advance the timing and it was hard to start. It was a real PIA.

[Kern Dog]

Yes, advance your timing. That´s it.

OOOf ! May NOT be the right thing to do!

Check the Hughes engines website. I thought I recall reading about this there before.
I recall talk of how engines run lean during cam break in/engine break in because while the engine is running at the fast idle, there isn't enough load on the engine to fully transition from the idle circuit to the primary circuit. I read either there or elsewhere that a fix is to install bigger jets or a lower numbered power valve to enrich the mixture JUST for the break in. Of course, you'd want to properly tune the carburetor afterward using an 02 sensor and air/fuel meter.

[John_Kunkel]

How is break-in any different than running at a fast idle with no load after break-in?

[Kern Dog]

An engine under load will produce less vacuum. An unloaded engine will not have the drop in vacuum that triggers the opening of the power valve.

[kamkuda]

I would pull a couple plugs and have a look.  Check if you are running lean (white deposits)

[John_Kunkel]

An engine under load will produce less vacuum. An unloaded engine will not have the drop in vacuum that triggers the opening of the power valve.

Great engine 101 but how is running at a fast idle with no load during break-in any different than running at a fast idle with no load after break-in?

[Kern Dog]

I must have missed something...
Did't the Op ask about red hot headers during a session with the car not in motion?

[John_Kunkel]

Yes, and most correctly stated that retarded timing was the most likely cause, not a lean mixture.

Your reply suggests that any time an engine is run at a fast idle with no load it will run lean....just ain't so.

[BigBlockSam]

the car is running great now. it was a bad distributor