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Discussion Starter #1
HEADER FAILURE

Well, My theory was correct, or so it seems. I finally got the new headers on and did some shadetree exhaust work. ;) The car runs fine. I do have some bad exhaust leaks, but it sounds quieter than it did before, LOL.

My cooling system is in bad shape, though. However long the engine ran against that backpressure took it's toll. . . But it never does end, does it?
 

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Glad your car is running, but I believe you're 180* out. Exhaust backpressure is caused by restricting exhaust flow. Crush your tailpipe and you create additional backpressure. Broken welds, pin holes, etc. in headers do not create more backpressure. If anything, they relieve backpressure. Driving along at 80mph and your car stopping dead is not going to be caused by pin holes or cracks in your headers. After restarting, your car only reving to 1000 is not caused by those header problems. If the headers were in such bad shape as one or more tubes (or the collector) was completely blocked with zero airflow, that would be a different story. The problem sounded more like an ignition system starting to go bad, or the beginnings of a fuel related problem. Hope it works out...
 

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Robert, is it possible that you just had a plug wire come loose or a cracked plug? I'm with the others that it seems unlikely that the broken header would prevent the car from running. It wouldn't really be any different than running open headers, although it wouldn't be real good to have that cool air getting in that close to the valves.

I would also look real close at your plug wires. Maybe take a gander at them at night to make sure you don't have a light show going on under the hood from cross firing.
 

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Discussion Starter #4
Well, take a look at the drivers side header below:

http://pic4.picturetrail.com/VOL55/689808/1145806/31531677.jpg

The #8 tube is short and has to make a hard bend before the collector. After that, because the way the collector curves towards the block, the exhaust flow needs to make another bend, about 70 degrees - into a pipe that has 3 bends, narrowing maybe 2", before it goes into a straight 2-1/2" pipe. So, it's already stifled, compared to the passenger side header, which flows out of a better design into a less restrictive pipe. The boom I heard on the road was the rest of the weld holding the 4 tubes together (in the center) blowing out. So my theory revolves around the idea that this new 'exit' altered the flow dynamics inside the header enough to become a restriction. All I changed were the spark plugs (the same ones used on the initial restart with the old headers) and the headers. . .
 

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Discussion Starter #5
I'll meter the wires this afternoon. If I'd had a decent meter handy I would've done it already. Maybe I'll take the hood off, do a high rpm run tonight with the lights off, and see if there are any sparks. ;)
 

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You are right, backpressure can be increased with additional openings. Headers are designed to scavange the exhaust, pull it out of the cylinder, not just a pipe to allow the exhaust to flow into. If they have extra openings, ie: cracks, holes, the efficiency of the scavange effect is reduced. So, although a smashed tube can increase backpressure, so can unwanted openings. The same holds true with mufflers. The most "open" design often fails to produce the peak tork which "closed" designs due, since they reduce the scavanging effect. ::
 
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