964 glowing heat exchangers. What's up?

[silver911rdb]

Hello, i just finished helping a friend rebuild his 964 engine. We started it for the first time today to do the initial 20 min break in. Everything looked normal. 4 min into the break in I noticed the headers ( inside the heat exchagers were starting to glow red). We were only reving it at 2000rpm. We stopped the motor. Any ideas what would cause this? I'm guessing it was running lean. Not sure why.

[J Richard]

Great deal of friction/heat in a fresh build. Everything is tight. It's important to make sure that the temps are kept in check and that the AFratio is good.

[silver911rdb]

After some reading, I think we'll check the fuel pressure. Maybe it's not where it needs to be and causing a lean condition.

[wwest]

plugged catalyst?

[silver911rdb]

Cat was hollowed out so that wouldn't be it. I checked ignition timing with a timing light. Definitely running advanced and not retarded timing. Need to pickup a fuel pressure gauge to check that next. Anyone know what the pressure is supposed to be?

[mreid]

Don't know about a Porsche engine with headers, but on all American V8s that's normal when running at 2500 rpm for 20 minutes to break in the cam. Thin metal headers at above idle rpm while sitting stationary and that's the result. You could blow a fan across the engine as that helps.

Hopefully, someone with more Porsche specific experience will post.

[silver911rdb]

I ran my 85 911 with a 3.5 engine for about 5 minutes at 2k rpm. Temps seem to stabilize around 730-750 degrees. I used a IR thermometer. At least we now have a frame of reference for the next time we run the 3.6L