Glowing Exhaust Manifolds 1992 454 TBI 7.4L P30 Motorhome

[jay72]

You're going to swap manifolds for headers so then you'll have glowing red headers.
On my '92 454 I have headers to dual 3" exhaust all the way back to the bumpers. What I said before about GM changing to a steel "shorty" header type manifold, the point is steel is less prone to crack. IMO headers are more likely to glow red because they're thinner than cast iron manifolds.
Heres a video I made several years ago, this is whats going on inside your exhaust. https://youtu.be/CLYi4JDnTSQ
And BTW, haven't changed anything on that engine since, except oil and filters, and it's been run several times for 24 hours straight fully loaded in the bed while towing a car on a trailer. Do I care if my headers are red? No I don't.

[Kaweh]

by the way thanks for sharing this video Jay. I wonder what might happen if i take the manifolds off and run it. But on my rv there are a lot of power, oil and what not lines running right next to the driver side manifold. Do you have a link to the right steel manifolds that you are referring to?

[jay72]

Do you have a link to the right steel manifolds that you are referring to?

I tripped over one at the junkyard today. I've seen a lot of this type on motor homes. I can only assume GM used these because iron cracks too easy at high temperatures.

[Fast355]

I tripped over one at the junkyard today. I've seen a lot of this type on motor homes. I can only assume GM used these because iron cracks too easy at high temperatures.

Holding closed loop at higher loading can cause the manifolds to glow as well. This is what my coated stainless headers on my Express already look like. The coating is discolored, chalky looking, almost looks like it was torched with an acytelene torch. I am thinking it gets quite hot pushing a brick into the wind at 80-90 mph especially into a 20-30 mph headwind. Those are LT1 90* metal plug boot shields designed to reflect heat off the plug wires.