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Headers
Hey guys,
Is there some secret to bolting up headers that I don't know? I believe I have an exhaust leak coming from the passenger side due to the loud and annoying CLACK! CLACK! CLACK! I hear from that side. Sounds kinda like a loud VW bug at idle but the sound disappears at higher rpm's to the low rumble of my Bursch muffler. I've taken both headers off and bolted em' back up but still the same noise. Next question is how many horsies could I be losing due to a small gap between the head and the manifold? Pete ------------------ 77'Carrera3.0 www.geocities.com/pcafaro2000/carrera30.html |
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03-03-2001, 08:35 AM
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Are you sure you don't have a crack or pinhole in the flange or header itself?
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03-03-2001, 09:07 AM
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No holes anywhere.
Pete ------------------ 77'Carrera3.0 www.geocities.com/pcafaro2000/carrera30.html |
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03-03-2001, 09:29 AM
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It wouldn't be the head studs would it?
------------------ 1978 911SC 3.0 roseneck@cyberbeach.net |
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03-03-2001, 01:34 PM
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What kind gasket are you using? I used the type with a metal ring during my installation last weekend. The gaskets have more metal on one side than the other. I had first positioned the gaskets with the "more metal" side facing down, and experienced major exhaust leaks. I R&Red the exhaust and repositioned the gaskets so the "more metal" portion faced upwards, towards the head. No exhaust leak with the gaskets in this position. Hope this helps.
---------------------- Paul 78SC Targa |
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03-03-2001, 01:39 PM
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i've got the same ones.. I'll see which way they're facing and reposition accordingly.. I hope that's all it is.. My head studs are fine.
Thanks, Pete ------------------ 77'Carrera3.0 www.geocities.com/pcafaro2000/carrera30.html |
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03-03-2001, 02:22 PM
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Did you replace the gaskets with new ones?
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03-03-2001, 05:13 PM
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yes... I might have to double up on the gaskets if I can't get it sorted out..
Pete ------------------ 77'Carrera3.0 www.geocities.com/pcafaro2000/carrera30.html |
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03-03-2001, 07:00 PM
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There was a recent thread where someone noticed that their headers did not have a flat 'deck.' That is, the mating surfaces for the three flanges were not flat and straight. On other cars I have found this common, and I consider it somewhat routine to take exhaust manifolds to the machine shop to be 'decked.'
Making sure valves are as perfectly adjusted as possible helps minimize the effects of worn valve guides. It does not repair worn valve guides, but it does make them operate as good as possible. ------------------ '83 SC |
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03-04-2001, 01:59 PM
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Superman,
I think you've hit it on the head. Upon the last removal I noticed that the manifold surfaces are somewhat cockeyed. I thought that they would form up as they were torqued down. I guess I'm off to a machine shop this week. How much $$ is the norm for this service?? Thanks, Pete ------------------ 77'Carrera3.0 www.geocities.com/pcafaro2000/carrera30.html |
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03-04-2001, 02:25 PM
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I'd want to pay $20. I'd be disappointed at $40, but then I'm cultivating an old-fashioned attitude. It's not a complicated bit of machine work. They just need to be ground flat.
FWIW, I've seen a lot of exhaust manifolds that were not straight. All of the used ones and many of the new ones I've seen need milling. ------------------ '83 SC [This message has been edited by Superman (edited 03-04-2001).] |
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03-04-2001, 06:37 PM
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I'm having the same problem after installing my SSI's. How much out would the flanges have to be, would 1mm make a difference or would the studs pull this in?. It diffently gets worse as the engine warms up. Would a intake leak cause the same noise?
thanks ------------------ Martin '70 911T |
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03-05-2001, 12:10 PM
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When I ran into the same prolem, I doubled up on the gaskets and the problem was solved.
If the mating surfaces are out, then there definately will be a leak. Machining is one alternative, but if you can get some gasket material and put it behind the OEM gasket - downstream of it, then you should be ok. Steve |
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03-05-2001, 01:51 PM
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I'll be under the car again this friday afternoon and report to you guys know what takes care of the situation.. Has anyone else noticed a small power loss?? I think all the horsies are there after 4k but it definitely feels sluggish up to that point. Maybe the whole back pressure thing.
Pete ------------------ 77'Carrera3.0 www.geocities.com/pcafaro2000/carrera30.html |
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03-05-2001, 08:40 PM
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