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Small Block Header port design and gasket area problem
#1874219
07/20/15 12:13 PM
07/20/15 12:13 PM
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Joined: Jun 2006
Posts: 3,075 Eastern Ohio
mopowergtx
OP
master
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OP
master
Joined: Jun 2006
Posts: 3,075
Eastern Ohio
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I picked up a set of Summit Brand ceramic coated small block headers yesterday and when I got them home and out of the box I see that there's no way they'll seal up on my ported J heads. My ports are matched to the Felpro http://www.summitracing.com/parts/fel-ms90460 gaskets. The raised area around the port on the headers is too short on the bottom side of the port. The outside edge of that machined raised area on the header lands in the port on the head and well of course with no area on the head for it to match up against itll leak straight out. So my question is whose headers that Summit sells will work on my heads? Dougs maybe? But they dont say theyll fit an F-body but I would think a manual steering console shifted no torsion bar in the way 1979 Volare would have an easier time than say a 73 Dart getting them to fit. So have I screwed myself port matching to that gasket or is there a header thatll work? I saw in the Flowtech header reviews on Summits website Im not the first guy to run into this trouble apparently. The single review they had was leaking out the bottom of the port with no way to fix it.
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Re: Small Block Header port design and gasket area problem
[Re: mopowergtx]
#1874332
07/20/15 02:40 PM
07/20/15 02:40 PM
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Joined: Feb 2015
Posts: 2,075 CA
crackedback
top fuel
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top fuel
Joined: Feb 2015
Posts: 2,075
CA
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So have I screwed myself port matching to that gasket Yes you did... You'll likely need to add material to the header port sealing surface.
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Re: Small Block Header port design and gasket area problem
[Re: mopowergtx]
#1874345
07/20/15 02:56 PM
07/20/15 02:56 PM
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Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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There are two port sizes on small block heads, The 273 size, which is smaller than the 340 size ones. In fact the stock manifolds on my 87 Diplomat were very close to not sealing on the stock heads on my 65 273, top to bottom, maybe 1/8" overlap total. Both were untouched openings. I suspect those headers have the small port openings.
All you can do right now is make an adapter plate that'll seal to the head and the headers, short of buying new headers or heads. Which will kill the idea of gasket matching.
Unless the overlap at the top of the port is enough that you can oval the mounting holes and drop the header down to seal?
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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Re: Small Block Header port design and gasket area problem
[Re: Supercuda]
#1874424
07/20/15 04:54 PM
07/20/15 04:54 PM
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Joined: Jun 2006
Posts: 3,075 Eastern Ohio
mopowergtx
OP
master
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OP
master
Joined: Jun 2006
Posts: 3,075
Eastern Ohio
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Thought about slotting the bolt holes vertical to shift the opening up. My other thought was if a machine shop could surface the raised area flush down to the 5/16" thick flange area and basically turn it into an exhaust manifold type seal. But how/where are the tubes welded to the flanges? Are the tubes pulled through hammered out then weld bead built off that is now my gasket area? Or is the pipe welded inside the opening of the flange? Only then could they be surfaced.
Last edited by mopowergtx; 07/20/15 04:55 PM.
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