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Old 06-27-2005, 02:36 PM   #1
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Default Final thoughts on Exhaust porting

On the 92-95 L27/L67 tubular manifolds, there is the risk of welding the outside of the flange in order to be able to port out the OEM weld on the inside. There is huge advantage to doing this (you can port an extra 16-20% on each pipe outlet).

Our manifolds are gasket-less from the factory. To play it safe, weld like I did in my other topic, 'stitch' welding the outside, and letting it cool in between, or pre-heat the entire assembly first. There is still a risk of warping or misshaping the flange from the localized heat caused by the welder. The best solution at this point is to use manifold gaskets, which are available. This also allows for a little flexing of each manifold to help prevent the cracking problem I found and had repaired.

Mine is going back together with Fel-Pro gaskets from Autozone. They're $8.99, but I don't know if that'* a pair or not. I'll find out when they come this week. FYI, I got every gasket on the engine for under $60.

Gasket maker (tube)
Thermostat housing gasket
Thermostat rubber seal
EGR valve gasket
Exhaust manifold gasket
Timing cover gasket
Water pump gasket (fel-pro, in case the water pump comes with something cheap)
Doughnut gasket for the downpipe to rear manifold
LIM manifold gaskets (4 pieces)
Valve cover gaskets

The only gasket I could not get from there was the TB gasket, and the Supercharger gasket I already got from the dealer.

I'm a firm believer that had the exhaust manifolds come with OEM gaskets, they would not have cracked, or at least not as badly.
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Old 06-27-2005, 07:37 PM   #2
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Good luck with the gasket job and your right about the exhaust gasket preventing more cracking, should have come that way.
They quoted me $49 for a tb gasket up here at the dealership, I'm sure he was lost in the drop down menus somewhere? Got mine from intense for <$7
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Old 06-27-2005, 11:14 PM   #3
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$12 from the dealer here.
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Old 06-28-2005, 01:46 AM   #4
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advanced auto carries the throttle body gasket will, they had to order mine but it was definately cheaper than $12, i got the felpro gaskets for the manis too. mine should hopefully be welded and ported at the end of the week.
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Old 06-28-2005, 02:33 AM   #5
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I don't have an Advanced Auto.

I'm betting the torque value will be different on the mani'* with the gaskets. I need to find the right value. It SHOULD be lower than OEM spec without the gasket.
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Old 06-28-2005, 06:32 AM   #6
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i hear ya on the gasket issue you gotta have room for play
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Old 06-28-2005, 09:35 AM   #7
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Am I right in the assumption the gasket would keep or minimize the cracking because of the give?
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Old 06-28-2005, 10:21 AM   #8
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Yes, but I'm in better shape to begin with, as I welded the cracks where they 'wanted to be' if you know what I mean.
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Old 06-28-2005, 10:24 AM   #9
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Quote:
Originally Posted by willwren
Yes, but I'm in better shape to begin with, as I welded the cracks where they 'wanted to be' if you know what I mean.
Mmmm yup..sent mine to Machinist Dave for the welding guy to take care of...those guys that work on airplane parts do such nice precision work.
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