Headers Glowing: Melting everything!

Hey guys, the 1969 Camaro 350 I was building is finally done and went into the car I'm putting it in (Caprice)... During the cam break in the headers started glowing cherry red and in some spots as bright as a pumpkin. The radiant heat caused some of the spark plug wires to ignite, and melted some wire loom, the plastic steering gearbox casing, and a vacuum globe. I hadn't had the chance to set the timing, and I have the headers going into a crossover that leads to a 2 1/2" exhaust. I've heard a few theories: too lean of fuel mixture, horribly retarded timing, too much back pressure. The ignition timing theory was the one pushed the most on me. After I replace the spark plug wires are wire loom I plan to use some of that heat resistant sleeving that supposedly protects up to 2000 degrees of radiant heat and 1200 degrees of continuous heat on the spark plug wires. The carburetor was properly tuned on the previous engine. My question is, will properly timing the engine keep the headers from heating up this badly, or will more need to be done? I appreciate any help.

First off, get the timing right. I'd also go over the valve adjustment and look for a possible too tightly adjusted valve. It wouldn't hurt to richen up the mixture at least until you get it to run right, then you can back it off. Go over the cooling system and make sure the thermostat is opening. Look for a soft or collapsed hose just to rule it out.

I'm not a big fan of headers on street cars just for some of the things that you've already run across. Cast iron manifolds can be modified for better flow and can add 25-40 HP if they're done right.

Bob

from the headers back do you have good exaust? because it sounds like it's not going threw from the headers back.but tming could be your problem also but cherry hot it has to be way out of time i doubt thats your problem just out of time.....

Not setting the timing during run in is a huge mistake!! This is the most critical time on a new engine, what do you think was happening internally while those headers were glowing?

What RPM were you doing your break in at? I check and set timing at 30* advance as soon as rpms are brought up to 2000. Years ago when I didn't I had red headers to but never hot enough to melt wires.

I had the RPMs at 2300 RPM (Instructions that came with the cam said proper break in should be running 2000 - 2500 RPM for 20-30 Minutes). As for initial startup and running the engine, I was going by the book (a 1983 edition "How to Rebuild you Small Block Chevy" book to be exact). I know the book is old, but I figured it should still be valid. I followed it's instructions on placing the distributor and the book said to start the engine and if everything sounds fine (as in no detonation, clattery valves, or anything of that sort) wait until the end of the break in period until properly setting the ignition timing at idle.

If you haven't already done it, drop the exhaust after the headers to see if it makes an immediate difference. I've seen rags stuffed into y-pipes before where someone forgot it or did ya a dirty. Run a piece of wire through the cross over pipe and even the headers themselves, also tail pipes if you have them.

Bob

I am amazed here, built at least 20 Hemi's and Maxwedge Mopars, no one I knew including pro engine builders, ever ran an engine during break in without timing it, have you done this yet, even 10 degrees back can cause this, but with no load the engine sounds fine, this is really just basics.

Yeah, I do know that under no load, even a severely advanced idnition timing will sound perfectly fine. I will be timing it as soon as new wires are put in along with the heat resistant sleeves to protect the wires from radiant heat. Once timed properly, should the under hood temperatures be acceptable, or should I take more precautions (like header wrap)?

Never had any need to do anything with headers as long as there is a reasonable distance to the wires.

I always have a timing light ready to go when I light up a new engine. I also mark on the intake manifold where the vacuum advance is pointing to before I take it apart. That way I'll be in the ballpark once it starts. Timing marks should be clean and easy to read, anywhere from 4-8 degrees advanced is safe and will get you past the cam break-in.

The header wrap is optional as far as I see it. It does dampen some of the header "ping" and will reduce under hood heat a slight amount, but may benefit any tubes close to the starter or other wires.

Bob

After properly timing the engine, I'll keep an eye on things and if they're still getting too hot, I'll wrap them. Thanks for the advice guys! I'll keep posted as to how things go.

Well guys, timing fixed that problem beautifully. Thanks for the help!! It turned out it was initally set at 7 degrees ATDC. When adjusted properly, the difference was like night and day.

Well guys, timing fixed that problem beautifully. Thanks for the help!! It turned out it was initally set at 7 degrees ATDC. When adjusted properly, the difference was like night and day.

So basically, you're telling us that your timing was retarded.

:P

Yep.