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Would you grind on these header tubes? |
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rang-a-stang 
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Joined: Sep/25/2018 Location: Camarillo, CA Status: Offline Points: 272 |
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 Topic: Would you grind on these header tubes?Posted: Mar/21/2020 at 11:58pm |
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I spent some decent time ensuring the exhaust ports are matched to the exhaust gaskets when I built my 401. I was not able to port match the header flange itself though because the header had too much movement relative to the gasket for me to correctly determine where it should go. But now that they have run for a while you can see how terribly they match the exhaust ports! These are probably killing TONS of flow...right? I guess that's what I get for a set of headers this cheap.
Anyway, would you take a die grinder to these to hog them out a little? I am worried that I will eat through the tube and create leaks. At the same time, some of these exhaust ports are really bad...    |
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79 Cherokee, 401
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WesternRed
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Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5798 |
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Posted: Mar/22/2020 at 12:06am |
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Those images are not really showing gasket/port mismatch. Would be better to lay a gasket over the top and see how it lines up and do the same on the heads.
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I've finally given up drinking for good...........now I only drink for evil.
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PHAT69AMX
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Joined: Jul/07/2007 Location: West Virginia Status: Offline Points: 5919 |
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Posted: Mar/22/2020 at 1:01am |
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On the cheap dogleg headers I had, the surface that seals to the head was the tube to flange attachment weld bead(s) that had been slightly flattened out with a belt sander or whatever. I had a couple few additional beads welded around the existing ones which I thought were to narrow, and used a large flat file and good work holding to then 're-surface' flat the header to head sealing surfaces which were then considerably wider than before because of the added weld beads... I guess the point is how wide is the sealing surface on any given header most likely would play into the sealing success rate.
( edit, wrong, carbon witness shows only the gasket hole size and shape, not the cyl head or exhaust ) Yes, one must use judgement and prudence when grinding / blending NOT to break through the tube. Alternatively, one can have a welder run a bead around the Tube and flange on the OUTSIDE as insurance, but watch bolt clearance. A rat tail file or grinder can also be used on the outside bottom flange edge to chamfer it to ease spark plug socket clearance. I see a lot of areas that would greatly benefit from additional weld beads being laid on the mating surface. The AMC dogleg exhaust port shape just has to give header manufacturers headaches... ( edit, wrong, carbon witness shows only the gasket hole size and shape, not the cyl head or exhaust )  Edited by PHAT69AMX - Mar/22/2020 at 10:52am |
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WesternRed
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Posted: Mar/22/2020 at 3:04am |
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I don't think that is the case, the gasket will only be compressed where it sits on the weld bead on the header flange, so exhaust gasses/carbon can get into the space where the gasket is not clamped. |
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I've finally given up drinking for good...........now I only drink for evil.
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rsrguy3
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Posted: Mar/22/2020 at 6:11am |
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My thoughts exactly. The only way to know for sure is to weld more bead on the inside, surface, fit, run, remove and recheck. In any case, what are your power requirements? Why does this matter? I'm not sure your going to get perfect fitment without pulling the head and custom precision fitting new thick flanges to the ex ports. I'm assuming your doing this on a budget, can you find a pair of thick flanges and re-use your tubes, how long can the car be down?
Edited by rsrguy3 - Mar/22/2020 at 6:17am |
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javguy
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BassBoat
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Posted: Mar/22/2020 at 7:12am |
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I ground the flanges, as you would predict, ground through the tube. Had my friend weld up from the outside. Held up OK.
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PHAT69AMX
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Posted: Mar/22/2020 at 10:49am |
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Okay, can see what you all are saying, the carbon witness marks show
only the opening in the gasket, not the opening in the cylinder head or the exhaust header. My incorrect statement(s) suggest a gasket with Zero Thickness, which uh... ain't happenin'...
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rang-a-stang
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Joined: Sep/25/2018 Location: Camarillo, CA Status: Offline Points: 272 |
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Posted: Mar/22/2020 at 1:46pm |
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Here is my head after gasket matching
 Here it is now (after about 1000 miles and header removed, most of the REMFLEX gasket scraped off:  Here are my headers with the new REMFLEX gasket laid over them:   These are Hedmans. I think I don't remember the part number:  |
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79 Cherokee, 401
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rang-a-stang
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Joined: Sep/25/2018 Location: Camarillo, CA Status: Offline Points: 272 |
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Posted: Mar/22/2020 at 3:07pm |
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I'm not really looking for perfect but on at least #8, almost the entire dogleg is blocked. Some ports, like #2, there is a good 20% blockage all the way around. I would like it better than what they are. I am budget conscience with this build but will spend money when I need to. Another set of headers would be $300'ish, plus exhaust work to get the Y-Pipe to match. This Jeep can be down for a couple weeks if need be but hopefully not. I know Bulltear has a nice header flange but they are $109/side. I am a terrible welder and have a terrible HF welder. Maybe I can pay a buddy to run a bead around the outside then at least bevel the inside? I sent a tech email to Hedman today. I guess they are in Whittier (not that far from me) so hopefully they can offer some advice or warranty work?
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79 Cherokee, 401
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jcisworthy
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Joined: Jul/23/2009 Location: North Carolina Status: Offline Points: 2805 |
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Posted: Mar/22/2020 at 3:40pm |
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It is up to you but it is better to weld around the flange first if you do.
I have seen exhaust ports flow the same or more air on the bench when holding a pipe in hand over the exit and raising it up. The port does not fall off until about .200" or so when raising the pipe. I was told by a expert in the industry that he once raised a pipe until the flow fell off then welded tabs extending into the header pipe the height flow fell off and the engine picked up 25 hp. I never tired it but it could help with pulsing and it does not hurt flow on a bench up to around .200" raising the pipe, with an AMC dog leg anyway. As far as flow goes it I would say it is not hurting anything. As far as power goes there is only one way to find out.
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PHAT69AMX wrote: