plugging this port on headers

[Schurkey]

Almost certainly an inverted-flare fitting. If so, no "sealant" needed, you'd just have to find an inverted-flare plug.

Kinda surprised that it's Metric.

 

[KRS1]

Thanks guys, I just picked up the Doorman plugs today. I will try them out with sealant.

 

[Schurkey]

Just about guaranteed to be the wrong plugs, even if the thread size and pitch is correct.

What sealant do you plan to use that will stand up to exhaust gas temperature?

 

[KRS1]

Here is closer look at the threads. They actually seem to be "straight threads". When I brought them into the fastener shop they measured them and they mentioned they looked straight.. The plug does seem to go go down the full length of the threads..
The headers are Flowtech part # 11508FLT

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[Supercharged111]

Nobody said the threads were tapered, it's the seat that's tapered. Or were you able to get away with a copper washer and seal it at the top of the bung as opposed to inside?

 

[KRS1]

Hello again,
Just wondering; if the plug is able to be tightened all the way down the threaded portion hole doesn't it effectively block all the exhaust gasses? For sure, there will be a void where the plug stops and the tapered area will be open but won't the exhaust gasses be blocked there?

 

[PlayingWithTBI]

I would think it all depends on the quality of machining since you're relying on the tiny contact surface IF the threads themselves don't help to seal it.

Maybe a copper crush washer down inside? Kinda like @Supercharged111 suggested only down inside.

 

[Supercharged111]

That's what I was asking, what part of the plug bottoms out? The shoulder under the head up top or does it bottom down inside?

 

[KRS1]

ah ha, no the plug doesn't bottom out. In the picture below this is the maximum the plug goes down.
I guess my options are:
- hope it seals as is
-copper crush washer down inside
-find a thread sealer that withstands high temperatures
- weld a "sealer ring" around it
- find a shorter plug that the shoulder contacts the top of the header plug port
-get the port fully welded in

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[Supercharged111]

Seeing how I have a welder, I'd personally just weld that sucker home.