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Dog leg headers on square port heads.Gakset? |
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348AMX 
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Joined: Jul/03/2007 Location: Massachusetts Status: Offline Points: 4165 |
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 Topic: Dog leg headers on square port heads.Gakset?Posted: Aug/01/2007 at 11:37pm |
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Using dogleg headers on my suqare port 343 heads. I thought the dogleg gakset would leak because there was a section on the head that wasnt covered where the dog leg on the gasket curved around at least that is how it looked, then I got a reply from a concerned member that he DID use the dogleg gakets on square port heads and they sealed and it was the square port gaskets that made them leak. Would it matter at all what gasket you use with the rec prt head and dogleg headers combo?. I could always stick a small section of gasket to cover the small spot on the head that the dogleg gasket isnt covering? When I bought this car it had the dogleg headers on the square port heads but I cant remember what gaskets where there, Thanks!
Edited by 348AMX - Aug/02/2007 at 12:28am |
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Steve_P
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Charter Member Joined: Jun/28/2007 Status: Offline Points: 3805 |
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Posted: Aug/02/2007 at 3:25am |
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lay the gasket on the head and trace inside it. Then see how it looks. I had constant leaks with dogleg headers on rect port heads. The dog leg area essentially overruns the flat sealing area on a rect port. Basically, the port shapes are totally different and it's a crappy match.
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348AMX
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Posted: Aug/02/2007 at 4:15am |
Steve,
thats what I did with the dog leg gaskets that came with the headers and you are right , there is a bare area on the sealing flange of the head that the gasket is not covering that the dogleg leaves open. The square port gasket will seal the entire flange area of the head such that the dogleg of the header itelf should be totally isolated from exaust gas, so what I'll do is check to see that there is adequate compression of the square port gasket in the small section that the dog leg header flange is not pressing against to keep it sealed. Best of both worlds would be to use the dogleg gasket and cut out small sections silicone those to the open section of the square port flange, so that there is gasket material there AND the dogleg gasket itself seals the entire header flange.
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6768rogues
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Joined: Jul/03/2007 Location: United States Status: Offline Points: 6236 |
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Posted: Aug/02/2007 at 1:12pm |
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If I understand correctly, it seems to me that if the dogleg header does not cover enough and a square port gasket covers it, eventually the gasket would blow out in the void area. Why not weld up the dogleg area of the header flange to fill in the void and make it a square port?
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Steve_P
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Posted: Aug/02/2007 at 10:45pm |
that would definitely help as that's the main problem area. the rectangular port is also taller
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348AMX
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Posted: Aug/02/2007 at 11:29pm |
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Welding would be the ultimate solution but they are up under the chasis and I am too lazy to take them back down.
 I did overlay the dogleg headers again and even though the dogleg section of the gasket leaves a space on the exaust port flange of the head the gasket does in fact seal the entire the flange all around so it would just need a little extra on the small spot that is not covered. The tops and bottoms of the ports are well sealed though. I agree that a sqare port gasket on a dogleg head is going to blow in the area that the gasket is covering the dogleg on the head port. I am going to put my original craccked square port head on my work table and get more exact clearances, ill probably just cover the part of the square port head flange that is exposed by sticking a small piece of gasket to it so it is completely covered. That should work fine for awhile. Whe I bought ht ecar in 87' it had dogles on it and never leaked and I didnt know about hte dogleg headers until I removed them a year later. So it will seal if done right.Edited by 348AMX - Aug/02/2007 at 11:49pm |
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348AMX
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Posted: Aug/04/2007 at 5:33am |
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Pretty sure I got this taken car of today as I bolted down the headers! To solve the gasket issue I cut a small section of gasket from an extra set and siliconed it at siamesed angles to the bare area of the flange on the port that isnt covered by the dogleg gasket, I did this for all the ports first let the silicone harden a bit and then siliconed the gaskets themselves to the heads. So now there are no bare spots on the port flanges of the heads and the dogleg flange on the headers is also completely sealed. It's really the only way to do it short of welding the headers. This should last a long time and I used the highest temp rated permatex silicone I have used before and it does not blow out. The headers cleared the ARP bolts nicely so the grinding I did 2 weeks ago worked fine.
Also installed the radiator and a shroud. Looks nice and should keep that 343 well chilled. All thats left now is to drop the trans pan to check the fluid filter, stick on a new pan gasket and fill with fresh fluid. I bought some 2 1/2" hedman extension pipes to connect the headers to the rest of the full exaust system. Best thing is they dont use collector gaskets! They slip on tighten down and thats it. The headers have a ball flange and the extensions are fluted and make a leak proof seal when tightened. Edited by 348AMX - Aug/04/2007 at 5:38am |
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PrimedAMX
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Posted: Jul/02/2013 at 6:46pm |
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Found this on a google search. Have the same problem. Did you get yours to stop leaking?
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jcisworthy
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Posted: Jul/02/2013 at 7:32pm |
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I had a car with that issue when I bought it and ended up stacking gaskets, rectangular on the head and dog leg on the header and it sealed. There was enough overlap between the two gaskets to seal but it was a temporary fix until they came out to weld. Drove it for a month without a leak.
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Steve_P wrote: