1968 Z28 302. i pulled out the 302 to discover the crankshaft broken in 1/2. i know right.... I have laying around a new 350 I built for my Jeep. Pain in the ***. I start it up, get the timing close and notice the Temp guage climing terribly fast as I'm attempting to break-in the cam. I get out and notice the ceramic coated Hooker Super Comp. Headers glowing red hot. This thing is about to boil over right? So I shut it down. This is a mild mannered 1979 350 Chevy with not much cam. I also installed my Team G intake with 750 Holley double pumper carb that's way too much right?.

The timing is real close with approx 12 deg initial and 35 deg total. The carb is way fatter than when it came from AED. I added 50cc pumps larger spray nozzles and smaller air bleeds. My first thought was a vacuum leak under the manifold. I removed it and replaced the gaskets. Same problem. This thing appears to be way lean. The spark plugs are clear as a bell.

Any thoughts?

 

sounds like your running way too rich, the extra fuel is burning in your headers and heating the crap out of your headers.

 

Glowing headers during break-in can be considered "normal". Besides this one, how many more times do you plan on sitting still, cranking 2 grand for 10 minutes straight? Probably none. Just keep an eye on it once you start driving the car.
The common causes for glowing headers are having the timing too far retarded (you already checked that), or the fuel is too lean making the engine run too hot. Running rich could make them glow, but the gas would then have to be burning inside the headers. That's not likely to happen unless your cam is making the exhaust valves open well before all (or most of) the fuel in the chamber is ignited, then the flame could continue in the exhaust. I wouldn't sweat it just yet.

 

They always say to run cast iron exhaust manifolds when breaking-in an engine just because of this. The heat can ruin the coating on a set of coated headers. I agree with "Camaro69"... don't sweat it.

 

same here seen it many times freaked me out the first time too

 

Glad I read this so I don't freak out when we break mine in.

 

I will check timing again and such, but it will not run but two or three minutes and send straight to over heat. This carb if anything has got to be way too rich. we'll see where it goes.

 

Check to make sure your coolant level isn't way low. Also, you have a new thermostat in there, and know that it isn't stuck closed? Even if it were stuck closed though, that wouldn't make the engine overheat in 2-3 minutes. Just thinking out loud!

 

Thanks. no thermostat at all, at least while breaking in, an i leave the hose stuck into the radiator and allow it to run out while breaking in a cam to supply even more cooling, and this still is not enough. also have dual electric fans. all tubes glow equally red hot, all the way to the exhaust pipes. larger volume pump brand new with serpentine belt set-up. the temp guage was moving almost as fast as a second hand on a clock. coolant is moving through the system.

 

What's wrong with filling the cooling system and closing it off? My thought is the water pump could be moving water faster than the hose is replenishing it, then your block never gets or stays "full". If that's the case, I'm not surprised it's running too hot.