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Header gaskets and fasteners

3278 Views 24 Replies 15 Participants Last post by  1996 roadmaster
The " new" thing for header bolts is the adaptation of a wedge loc design.

This design of locking system has its place in the world.
My opinion is holding on headers when a gasket is involved is not the place.
When torqued the outer serrations bite and hold.
The inner ramped set seat down on each other.
The system works when vibration tries to rotate the fastener.
The climbing on the ramp increases the bolt tension stopping the rotation.
If anything in the combination gives like a setting gasket, the system does not work as intended

In Nords own words

While we are here , gaskets relaxing,
Sure , heat cycles excelarate the settling and subsequent loss of fastener tension.
But, try this
Put a set of heads and headers on with composite gaskets.
Don't preheat, don't start .
Come back in a couple days and retorque.
Oh, they'll move !!!
In my humble opinion ,about the time you are installing magical hardware you are "fixing" something else.
Like surfaces that are not true or over thick gaskets designed to " fix" a crappy header.
I remember being told the big crown in a name brand header was to better seal as the flange was bolted down.
Ah yeah, your header pulled during the final weld!!!
As others have stated is is hard to beat ARP fasteners in the longest length that fit without bottoming.
Nothing beats repeated retorques until the settling stops.
Good true surfaces , you dont need tricks and thick magical gaskets
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100% agree. I don;t think I have ever had a header gasket fail on a well built header with a robust/true flange using ARP hardware and a good MLS or copper gasket. My only trick is make sure the surface area is clean, make sure the threads are clean, torque down and then check multiple times for the first 1k miles or so making sure to get some heat cycling in with WOT runs and long drives.

After that, I don't think I have ever had a header gasket leak or header bolts loosen up except for on really crappy headers where I have had blowouts likely from the flange not being true . I still check the bolts every so often afterwards but don't think I've ever actually had to turn one.

Of course it doesn't hurt to have an LS where you can fit a socket on every bolt and torque them to the actual torque spec so the clamping force is being applied evenly and consistently. One of the many pleasures of LS engines LOL
I used the ratcheting type of retainer, tightened them to the required torque and never had to touch them again. They were on the engine for about 5 years. They work great, and I would buy them again in an instant.
In reading other posts is appears to me it is not fully understood the function of the wedgelock system.
They do not take up expansion, they only stop rotation by way of their ramp design.

When fully torqued there is no spring effect to absorb expansion of assembled components.

Nord did develop a catch all type ( the X system) that also employs a Bellville (sp) washer to keep tension as components in the stack lost thickness resulting in lost tension.

But again, when the hardware is tightened to spec , there is nothing in the system to absorb expansion, only spring to follow compression or contraction.

The Bellville washer , you can lookup Schnorr washer.
I use those in some areas with success.

To more understand the ramp verses bellville here is an additional link.
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I used to use the FelPro permatorque header gaskets and they pretty much always leaked regardless of the header flange. Even the current CIA tri-y's I'm running which are arrow straight - on freshly milled heads. I've been using Remflex graphites and ARP's on this engine and they've never blown out. They do relax a f-ton and require regular checks for the first half-dozen cycles. To your point, it doesn't matter if the bolt is locked in place if the gasket relaxes. There's no "fix" for that other than to retorque.

As long as we're talking here, I also use anti-seize as a matter of routine on any steel bolt or nut that's going into an aluminum hole. Spark plugs and header bolts being the most common. Is this something that's common and worthwhile?
"Permatorque" ya sure Felpro!!!
Goes for their head gaskets too!
Even if the gasket never moves, everything else does.
Some of our alloy stuff, head retorque is an every race weekend ritual untill they finally stop.

Yes , I typicaly use smear of never seize too .

The NA racecars where I used 1/2 flanges , no gaskets just a thin line of ultra copper
If shim MLS is not an available choice, my old go to is the gray mr gasket ultrapro.
They are not stupid thick ,have graphite, and fine mesh inside so if you do leak a bit they dont blow out.
The other one I had success with is Percys.
It is wafer thin stainless with fuzzy graphite on them.
Looking at them one would say " that ain't gonna work" but they do.
Only thing, be prepared to bleed!!!! The stainless is razor sharp.
Many ways to do this right.
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Damn you guys are making me worried about the new Fel-Pros I picked up for my header install.
Is it just me or what? I have had headers on lots of cars for 40 years and I have never had one leak---NEVER. I just used the bolts that came with the headers. and would retighten them after 2-3 heat cycles and would never have a problem after that.
Is it just me or what?
No it is not you.

This is the tone of this thread, do it up properly, with quality parts and you don't need magic beans .
Thread was to illustrate why I feel , wedge type locking fasteners really don't belong in this application no matter what the experts tell you.

Now 50 years ago there where lots of crap headers with 5/16 flanges, welds at the ports that looked like they were finished by a blind monkey with a 18 grit grinder, gaskets that might as well been cardboard , and supplied hardware that was just junk.. You had the do a lot of work to those headers if you wanted them to seal.
Hooker Super Competition was what many of us would use.
Usually you were cutting the collectors open in the car and welding the merge point of the primaries within year and buying new ones within three. Total junk
I have only blown out one gasket on a stock manifold. It could have been cracked or warped who knows, it was a used engine after all.
Do yourself a huge favor a get the Remflex 2042 gaskets as Dan ,and many others recommended.
i have used arp bolts (usually for clearance) and torque when stone cold. after a few heat cycles retorque cold. done.
i have used arp bolts (usually for clearance) and torque when stone cold. after a few heat cycles retorque cold. done.
My first time on retighteng is always done when the engine is hot. Then afterwards its always done cold. Never had a problem doing it that way.
All good advice - with stock manifolds on these cars, absolutely remove them ASAP and have them planed flat by a machine shop. I bet you yours are warped by now. I also add 1/4" worth of washers and use longer bolts to give them some extra stretch room.
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This is an interesting video on how a professional machinist fixes a warped exhaust manifold.

Part 2...

Mine pulled a bit when welding the port side , so I too had to surface them . I dont have a shaper so I did them in my mill.
Slow going on 304 but got them flat. Using production MLS gaskets the surfaces need to be pretty good.
What method do you use to true yours when building headers ?
Trunk Automotive exhaust Gas Bumper Automotive exterior
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Admittingly, I put Stage 8 header bolts on the SS 23 years ago. They have that D washer and a C clip thing to keep the bolt from backing out.....there was never any locking, the bolts themselves have never moved. Since I have had the headers on a few motors on the SS, same bolts but without the locking C clip & D ring, no problem.

I also use FelPro standard header gaskets, never a leak. YMMV

Yeah Gerry, no need for any magic sauce header bolts
Damn you guys are making me worried about the new Fel-Pros I picked up for my header install.
Dump em and get the Remflex
@cappy p Probably picking up the Genuine GM MLS gaskets. No reason not to already have a shipment from RockAuto
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