Two cylinders headers glowing

[rsaun191]

Going crazy trying to figure this out.Engine is a 440 with repro crossram with two 625 carters.This car ran fine with this set up for years.Car has bas been sitting for two years because I installed a x pipe exhaust system and it made all header tubes glow.Never did bothered to fix it with that system.So recently installed two straight pipes on the hedman race headers.car has full exhaust.Number 5 and 7 tubes are glowing .Nothing else was changed on car.It has an FBO ignition that checks out ok.Timing was always fine where it is 34 degrees .The wires were replaced A while back but car has not been used so they look brand new.Was wondering could it be the difference in todays gas.I am assuming those cylinders are lean.Plugs in those cylinders look like they just have taken some heat almost look still new.compression in all cylinders is 180.I swapped the carbs around 5 and 7 still glow.Even if I can't fix It would like to know whats wrong
Thanks Rick

 

[WileE]

Jetting and spark plug heat range.

 

[Hemi Rebel]

Make sure 5 and 7 wires are not crossed

 

[rsaun191]

was told the same thing by Norm Brady.They are not

 

[eldubb440]

vacuum leak?

 

[cryplydog]

Valve Lash?

 

[Meep-Meep]

Probably mixture. The factory cross ram, I believe, required stagger jetting. Glow is likely rich, not lean.

 

[Garys1969RR]

Probably mixture. The factory cross ram, I believe, required stagger jetting. Glow is likely rich, not lean.

That rich mixture idea makes sense. The extra rich fuel/air mixture is finishing its burning inside the header pipes, causing them to glow.. A rich mixture burns more slowly than a lean one. Sounds as if its an intake manifold fuel distribution issue. Too much fuel going into that part of the manifold where 5 and 7 draw their mixture from. Maybe try leaning out the carb venturi that feeds 5 and 7? As an experiment to see if that eliminates the problem. See what the stagger jetting specs are.

 

[rscurtis]

If the plugs look like new, it's running lean.

 

[Meep-Meep]

If the plugs look like new, it's running lean.

Forgot that detail in the OP post. But high EGT can result from too rich or too lean. If we had cylinder hear temp data, or 4 gas analyzer, that would confirm rich/lean.

 

[jenkins71]

Might want to check for a blown head gasket... Had this happen to me and did some more poking around and found i had a blown head gasket between the two middle cylinders on each side

 

[383man]

I have seen retarding timing make headers glow alot of times as well as lean or rich mixtures causing it. If the plugs all look real clean like new then it sounds like a lean problem. Lean mixtures generate more heat then rich mixtures and if its to lean it can cause a lean misfire. If it has a lean misfire then the little bit of fuel in the cylinder that did not ignite can ignite in the hot header tube. How do all the other plugs in the eng look ? You may have a vacum leak afecting them two cylinders also. Ron